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The following are repair briefs for various 
equipment.The information is directed
to technically competant repair engineers.Generic terms have 
been used to make this info less model specific,eg terms like 
replace transistor Q123 have not been used.
The equipment is Music systems, compacts and portables then Audio Cassette and tape players. 
I would be interested in finding 
any other repair listings on the internet structured as i have 
done ie intended to be less model specific. For convenience using search-engines, 
use keyword divdevrep to target these files.

There is no point in contacting me about any of the following, the 
repair job may have been done 15 years ago .
I cannot clarify or enlarge on any of the following. Mains is 240V, UK




Should the location of this file change please use the keyword "divdev7" in 
a search engine to find it again


  

A number of the pictures are now apparently not downloadable, because the hosts have disallowed 
remote linking although not saying so. To view them , you have to remove the picture file name 
from the picture URL and put this .htm file name in its place 
and scroll down to the relevant pic.




 Music Systems, record decks 
AIWA CX770K Midi
Neither tape unit working
L play only dislodged sub pcb with contact switches.R rec/play
bent location spiggot that passes through hole in cassettes and the normal/reverse switch 
was separated and jammed so extended yoke of the join so it could not be forced out of
contact with the actuating lever.



 compact 1979 Aiwa L22, as always all the bands are perished,
that contagion again . I decided, this time, to liberally caster talcum
powder around the contaminated parts , my hands and goo pickers. Operating
at that stage , dry and dusty, avoided smearing on other parts, to remove
the bulk of the mess. Then meths on tissue paper and meths for general
smeared areas and some wool dunked in meths to run around the pulley edges
to clean out the gullies.
Anyone ever tried freezer spray?
My own cut silicone rubber bands will go back in there
Originals are of course as near to perished as the ones you're having to
replace.
I tend to use silicone rubber as much more available from "pound shops" /
kitchen supply shops etc rather than large minimum square metreage of
industrial neoprene rubber supply companies, techniques buried in the 3x
tips files off my site
http://www.divdev.fsnet.co.uk
The wide band for this Aiwa I will use a ring from one of those squash down
silicone rubber funnels ,
, just a shame about the lurid colours of the rubber
eg , http://img.hisupplier.com/var/userImages/2013-06/07/101820013868.jpg
In the UK I get them from Matalan, gives 20 bands of a good range of lengths
and if 3mm wide then can be split for 40 bands. The slight set to the band
does not seem to matter for centalising the band on baluster pinions
2 troubles with that is its ok slicing a square into 4 say but only 2 of
them
would have a fair face on one side, to go against the drive pulley.
I've tried slicing circular O rings, physically worked but the rubber seems
to be too stiff ,whatever the technical term is , restitution?, lack of
stretch for a given cross section area
The main problem with keeping old mechanical kit going is the requirement
for wide bands for bulbous balluster pulleys, and I've never seen that
format used as neoprene seals , neccessity being the mother and all that
Top LED BARGRAPH ONLY on play
Got inside this audio Low Pass Filter block, after desoldering the associated IC but problem was an ohmic cap,1.5mm diam x 5mm, in the base/former of one o fthe Tx.
Originaly measuring about 400 to 500R, now after desoldering, about 1000R
I had removed the cap, decided to lightly sandpaper the ends of the tube assuming the migration over the end surfaces and placed it in my usual place for such tiny items to pick up the DVM. But with my turning, there was some of that near invisible spider-silk hot melt fibre I had unknowingly on me from the previous job and that must have  flicked the cap off to the devil-knows-where. Didn't get to RLC measure the cap either.
Otherwise symetrical coils in there and other cap is 3.4nF and the first scrap coil I come across also had 3.3nF tiny tubular in it , so that will go in there.
So anyone been here before , and end abraiding would have been all that is required to reuse?, and more generally with such narrow dimension high capacity caps for reuse, would routine pre-emptive abraiding the ends always make sense
LPF green plastic casing with 2 transformers inside marked
061-01
8NIV
should anyone have data on such
ps
a lid for my small parts , under review tray, premptive action also 
Thats the main flat band sorted, the rest are less critical.
Original unstretched 285mm x approx 3.5x1.5mm. Area for area, silicone is more stretchy than neoprene , so 
about 50% allowance for that, a now working band of unstretched 250mm x 4x 2mm. Target was 265mm x4x2 ,
probably turn out to be too tight on speed check and will have to resort to cutting up my next size up solid 
silicone funnel as 250mm is the max,outer ring, for those collapsible funnels 
Remove top cover, remove 2sc of central escucheon and joggle around 
piano keys. 
2 deck sc at top , 2 recessed in base, 3 other on base
Disconnect front LED wire near 35V 1000uF
Remove rotationb sense PCB
P{ush deck rearward to clear front panel metal
R/Bk/Ocon , release near Q2.
Wires will break on repeated moving of the deck, reinforce all points with hotmelt glue before 
dealing with belts etc
2 sc only and circlip removed to release the rear 
capstan plate
Spindle 2.49mm 
Push side actuator arm to simulate cassett in to observe mechanism
Desolder the Dolby boards via the slots in the underside chassis
p6 of Dolby boards different DVM-D test , had some salvaged LM1011 to 
compare, p2/p9 of  8 to 10K not the 500R or so (varying) of the bad one, but desoldering 
showed they were ok, it was the low pass filter cap gone ohmic, green dual Tx marked 
061-01 8NIV. Slice into the corners of the plastic , break glue bonds and lever out the Tx, 
don't press the ferrite cups as fitted in
pin for pin equivalent to NTE2003.
Juddering non function of FF/REW? due to band in the wrong position, wrong rotation so instead of 
the idler grabbing into the capstan it is thrown away repeatedly. The band goes round both sides 
of the pulley and the far idler is just there to remove the single direction bias force off the bearing.
Replaced all 4 small tyres with standard O rings. Sometimes FF or REW would stop 
due to the O ring falling under the capstan/drum , needs the rear plate in place to keep position.
Tape up the dismantled rotation sensor pcb if powering up the deck as it will flop against the fuse.
Hall effect ? TO92 size device marked SONY 01A, DM-101A on the 
schematic and device type shown as a potentiometer
Remove the cover to the mains sw to give some space to observe the capstan, just. 
Mark white and black and strobed for 2.49mm spindle and 24.2KHz or 12.1 KHz , x2 or x4 speed.
Rotation sensing bands needed lighter gauge bands and the thinner of the 2 drive bands needed to be tighter 
as at end of spool the capstan slid on the band at max back torque in FF/REW?
back in working order, not tried it with analyser proper, but no audible difference to L and R tracks rec/playback for 3 spot frequencies, Dolby in  or out. Strobing to the capstan only needed about 3% adjustment probably more for age than different bands. 4 pulley tyres needed replacing also ,
small O rings, adequate but not ideal

Aiwa Z-L120K, 2000
Powered down after a few minutes of use, owner could not 
remember exact details , whether clock remained or totally 
dead. Would repeat the next time of powering up.
Remove side pannels and then the top cover (replace 
a sscrew to retain CD section in place for handling) 
to get to the 2 internal screws to release the whole bottom pannel. 
Nothiong found in way of loose connectors or visual inspection 
of solder or heavy twizzle stick or engraver with nylon bolt.
Maybe just week fuse holder tangs inside the mains plug.
o/p device voltages
0,-10,-1//0,30,1
0,-30,-1//29,12,28
transformer board
starting pin 3 22Vac,22ac,0,-20,-20,11.1,11.4

Aiwa LCX 352 midi system
The owner wanted to plug a vinyl deck into this system.
This conversion probably is applicable to most modern systems 
with no phono/cartridge level signal input.
Equalization is perhaps off and the signal level is probably a 
bit too high so next such conversion i will probably add 
a couple of presets in the signal line.
Where the tape deck play signal lines from the tape head join the screened 
leads to the main pcb solder in a pair of screened leads and take 
to the rear of the machine and an extra pair of phono sockets.
Plug the record deck signal leads into these and select tape mode.
To defeat the tape protect system butcher an old cassette by 
cutting the tape and use this as a dummy.The tape protect 
in reverse play on this m/c will not cut in.On other machines 
that will detect in play and reverse play it would be necessary 
to open a cassette,strip out all tape and leaders,loop around 
both spools with a rubber drive band.

Aiwa ZVM260 Compact HiFi
Disappearing main display and tape problems principally but also intermittant 
CD problems
The intermittant display problem was (YET AGAIN) heatsinking from large metal 
parts insufficently soldered in the original flow soldering operation. This 
time some of the pins to the cold-cathode display.
On switch on there is tape solenoid clicking in and out for a few seconds 
but no tape operation. The LH tape mechanism had failed to retract due to stretched 
drive band and the owner had forced open the door breaking the plastic 
flap catch. To replace the bands first remove the top CD unit firstly upwards 
at the rear clearing the optical output. Mark the track of the two tape 
main bands as completely different tracks. The RH tape drive band comes free 
easily but the LH is retained by one of the motor pillars. This is just a 
locating,not a fixing pillar. Force the motor on its flexible mounts to 
expose the small pip at the end of this plastic pillar and with a hacksaw 
blade (no handle) cut off this pip. The band can then be pulled through. 
Otherwise the whole machine has to be taken apart to remove the twin 
cassette section,who designs these things?. Use a couple of hooks 
to replace the band around the motor spindle.
To replace the flap catch. Use a 1/4 inch male spade connector as soldered to 
PCBs. Cut off one of the 2 mounts and bend the remaining one to a right 
angle, bond into the carrier plastic with plenty of hot-melt glue string.
Accurate posiioning is required otherwise the carrier will close but 
not open when pushed in the normal area.
The CD problems were 
1 Overnight occassionally the CD drawer would open of its own accord. Packed 
out the 1,2,3,4,5 etc switch board between it and the casing.
2 Occasionally would not read a CD, could be any CD. Resetting via the disk 
change switch would usually clear for the moment. Cleaned the lens and adjusted 
the preset resitor next to the laser.  Accurately measured the ohms across the 
ends of this preset and noted the original reading 
on the m/c and adjusted down 5 percent. Before replacing the 3 white 
foil ribbon cables especially the very thin one in the CD unit bind the ends with 
upholstery tape to reinforce.



Beocenter 2100, type 2442 , 1985
Phones output but not always at power up, 
speaker output.
Fuses under the cover near the mains transformer ok.
23V to the relay failure.
Originally thought TR7 in the ps for the protection circuit/
output relay driver circuit, but I don't have the manual for this one.
The emitter needs to rise to about 2V with 4.8V on the base 
before the relay driver changes state
It is between TO92 and E-line, slightly smaller than TO92 with a small flat
on the curved surface
It in pnp , marked
115
4XF
so not BC115 or 1154
or 2SB115 or 1154
Would it be short for B&0 number sequence preceding with 8320 so 8320115 ?
and 4XF as date/batch code for 1984 perhaps
Its that sort of size of a DTC115 , digital transistor, but about half the transistors in this music centre are of that size so unlikely.
Also that one and the others check out "double diode" test with DMM as
normal pnp transistors.
Used a BC558 with crossed-over legs.
The other ones npn etc, in this unit, of this small format, are lablelled
603 and M21 instead of 115.
Looking in the Beocenter manuals that I have, I cannot see this package in
the the gallery of transistor packages used in those units.
Perhaps they were a Danish manufacturer of mid 1980s
Problem area was around TR8 with undefined biasing from 
the pa line. Touching this line would trigger off 
state of relay to on.
TR1 ? in the pa was off wheras presumably it should be just on 
giving about 0.4V at the collector.
More than 0.6V or less than 0.2V in pa failure then 
the relay driver goes off.
Measured voltages , approx, as B,C,E
TR1 23.4,.04, 23.4
TR2 0.23.4,0 NPN
TR3 0,-23.6,0 PNP
TR4 -23.7,23.5,-23.6 NPN
0.4V remained, after power off, on the back to back pa 
47uF caps C1 and C2, 
so replaced, and also the 3 caps around the 
protect circuit, not all 10uF
Added 2.2M from 4.8V to TR8 base and 33K over 
R23
which otherwise just had in effect 100K to ground, 
 to give a definite 
bias so then the electrolytic could charge up 
and turn on the relay after the hold-off time.
Copver screw removal sequence marked on the base.
To inspect the power transistors slide the heatsink 
downwards.
The release cattch for the top cover aon the radio 
side had been pushed in fully.
Flimsy plastic. Removed and added a couple of small 
cable tie hoops to push the spring away from the 
plastic "spring" retainer so the metal spring cannot 
over-ride it and more closure force to the pin 
as it was a bit bent and bound on the holes.
The instructions on the base only tell you 
to push in this pin , not press on the grill 
section at the rear 1.5 inches in from inside to release the 2 
rear catches before sliding forwards.
16V ac on the one remaining front panel bulb.
Earthe plate between mike socket and motor , the 
separators degraded and metal very near the contacts.
If looking in the radio area mark the LED position 
of the dial scale on a known station before 
releasing the radio pcb , so can realign on reassembly

Beocenter 2200 no scale illumination. (1984)
Original T1 1/4 format bulbs were probably 13.7V could only 
replace with dimmer 15V ,40mA but gave sufficient illumination.
Instructions for removing casings are under the deck platter.
To slide cover off the scale area push the release pin near 
the dust cover right hand hinge. Mains switch is at the tuning control.
Screw down at least 2 of the deck anchors (under platten) before moving the m/c to 
avoid bashing the stylus as flops around a lot. Deck operation commenced 
by sensor to detect presence of a record.
In effect weighs records to set the radial 
start position. 10 to 70gm for singles 
and >80gm for LPs.
For anyone bodging a coupler for a standard 
pick-up the pins need to be .6mm diam and signal 
lines are 12 o'clock left ch and 3 o'clock Right ch,looking at the 
sockets on end of arm.
No tape functions - just a relay click noise.
Stretched drive band jammed against cover plate. 
Mark all 4 connectors before removing. 
Replaced both this flat belt and the square belt 
with the strange path, only 1/4 round 
drive pulley and both nylon pulleys.

Beocenter 2200 , type 2422, 1984
Missing cartridge and stylus, 120 GBP for a new 
one which a pensioner was not going to pay.
Beware aluminium platter only resting on 
centre, remove before turning over
Remove black plastic covers at the main hinged lid 
to reveal fixing screws. Undo base screws around 
deck area and the internal ones to release the 
inner deck surround, lift away after releasing the 
2 leftmost screws, marked "A" holding the static rear of the 
top cover.
Replaced with a standard moving magnet cartridge 
with elliptical diamond stylus. The cartridge 
did not properly sit in its stowage housing because larger .
Also heavier ,Added 25 gram strip of lead to the existing 65 
gram. The weighing mechanism at the centre of 
the platter needs about 100 gram to register 
as an LP, without it, registers as single.
If more anti-skating force is required then 
a light spring attached rearwards to the final 
lift activation wire , that also doubles , by 
deflection as anti-skating corrector.
The rearmost slide bar is the radial tone-arm 
posistioner which needs a bit of spiral cable wrap 
around the vertical white pillar to reposition the 
initial drop position with added cartridge.
The nearer long steel bar rotates slightly 
to operate the arm lift. Switch off at mains in 
mid play position if required to work on mechanism.
The cartridge stuck to the small socket housing 
on the end of the tone arm. 4 turned pin IC socket 
pins bent and fitted in the sockets , wired back to 
cartridge pins through a small plastic ring 
to take up space above the existing cartridge socket housing.
Bit of double sided tape to assist initial 
placement of new cartridge. 
One small cable tie around all and tightened 
and then when finally angled posistioned correctly 
lock in place with some dabs of epoxy glue. 
Paint black and stow the signal wires to try 
and improve the appearance.
In play mode the two main headers, DC 
11.3,0,0,10.3,0,0,0,0
42,0,0,0,0

Beocenter 4000 type 2431 , 1985
Loss of one radio channel and then much later loss of all functions.
Stuck in Aux input mode only, ps , pa and fuses ok.
Signal level LEDs responding to radio signal 
but nothing on output as cannot select radio.
Remove covers to lid hinges to remove. When reassembling 
make sure mains switch extender is in place and 
the click switch button tops are in line with  
the tops of the wells or the user buttons will not contact.
And section "A" with the hinges is fixed first and then "B"
Cover the heatsink with bubble wrap to protect 
the top plastic when opened clamshell fashion.
Lamps blown , measuring 17V ac , no load.
Control board uses LC7815, upc1362c, M51907P, BA820 
5V supply but to this "pipeline register" under micros in DATA
little info around for the BA820  , 
, 5V 16 pin 
pin 1 shift pulse, NC, data out, gnd, out7, out6, 
out5, out4, out3, out 2, out 1, out0 , gnd,
data in,Vcc, strobe in
Brown glue dabs had hygroscopically attected damp from 
the air and corroded through 2 pins on the LC7815
In Aux R36 to pin 4 had 11V across it 
as pin stuck low. Removced all such brown globs.
Radio uses LA3390 , LA1245, LA1235.
No output passing through one of the low 
pass chokes (transformer with numbe rof turns and 
3 caps but only 240R/50mH coil used) replaced with 
30mH choke.
Preamp uses TA7629 M51551 TD 62504 M51143
Some DC voltages set on radio 
10 way ribbon
-10,-10,19,-10,13,11,0,13,19,8
control board
0,5,5,5,5,4.2,5,5
ribbons to the front of tape deck A
6x5.1,0,0,4,0
0,0,3x 4.3
0,4x5.1, 4.3,5.1,5.1
0,0
0,5.1,4.5,0.06,4.6,0

Beogram 3000, type 5228, 1973
Very erratic speed and an annoying clicking noise.
Slide perspex cover hinge section rearwards to remove.
The legend on the selector central push 
pad had worn off and it confused me how 
that action was initiated, not seeing 
that as area as a knob.
Cured the main problem of erratic speed - solidified grease on the main
swing arm , stopping the thin moulded hard rubber?(dark brown colour) edged
pulley, freelyly swinging and engaging with the stepped conical motor bobbin
with the pull in of the main platter drive band.
Remove the 3 screws and 1 nut and then release the 
spring on this drive mechanism.
Release the wire "U" clip between the twoo sections that 
changes from 33 to 45 rpm.
Remove that cam with the black plastic cylinder.
But there is an intrusive noise associated with this pulley , once a
revolution. Nothing obviously wrong , no cracks, bulges or anything on this
edging.
The noise is from the intermediary idler pulley, once per pulley rev.
The noise was coming from the (forgotten the mechanical name) the pulley
that engages with the pin/plate that is moved  on adjusting the speed. That
shift pulley coaxial to the idler pulley, so moving the idler up and down
the drive cone bobbin, for speed change.
There was a tiny nick and gouge out of the aluminium of the active surface
of that "gear-box shift" selector pulley so flexing the plate on each revolution.
But at least I know that moped inner tube dodge works should anyone faced
with a broken /totally worn thin idler edging.
I run a strip of stretched moped inner tube around the edge and glued in
place to see what happens to the noise.
Measure 1500 ohm outer and 1520 ohm inner in my notes 
but forget what that refers to.
When power take off for the arm lift then the belt fell 
off as too slack.
Platter is 660mm circumference, ideal band is probably 650 mm 
but old stretched band was 680mm.
The only near suitable band I could find was a "halved" lorry 
inner tube band (see tips files) 580mm x 1.5 x2.5 mm 
rough surface to the outside.
Combination of too tight a band and the increased diameter 
of idler pulley meant the 33rpm was unattainable 
on the knurled knob adjuster.
Had to introduce a TO220 tab plastic insulator under 
the point of that adjuster to push the setting 
plate further away and higher speed ratio on the cone drive.

Bang and Olufson Beomaster 1200 tuner / amp
Very bad volume control on one channel.
Another cherished heirloom.Problem due  to a broken pot slider.
To get to the relevant area to desolder 
the pot.Remove the 3 screws on  the base to remove steel base panel 
after desoldering earth clip and mains wire to on / off switch and four 
signal wires.
Remove three of the most accessible of the 4 aluminium L bracket pieces 
that engage with the rectangular wooden surround and remove.
Remove long rear plate ,disengage from the 2 Din sockets.Remove black 
plastic front grill with the main switch lever pannel.Remome the small aluminium 
slider area cover pannel held by the 2 spring copper clips.The errant pot 
had a graphite insert that had broken or dropped out.Compared with other 
pot it was a conical shape just pushed into the metal of the slider.Replaced 
with a mushroom shaped pip from a cermet preset but diameter slightly 
bigger than original so opened out metal of slider.Placed in position 
temporarily held in with a bit of gummed label to be able to turn over 
and put a dab of glue on the other side of the graphite pip.
Reassembled pot and glued along seem.

B & O Beomaster 901.
All 3 indicator lamps had eventually failed so no mains-on indication and 
of course some awkward wedge ended bulbs.
5mm LEDs are just the right size to go in the recesses if the plastic 
skirt is cut away from each LED. The original bulbs are 12V,30mA so place 
120 ohm,2W resistors in series with each LED. Adjust the 2 presets on the 
board associated with the two matched tuning indicators. The Green indicator 
needs a strong radio signal to come on.

Beomaster 3000 - 2, type 2402, 1971
Nasty buzz from both speakers even zero volume.
Failed 4700uF, 70V capacitor on 60V line, 
middle of the 3 main electrolytics.
Only 40V Dc and 16V "ac on DVM" and buzz in 
test piezo earpiece.

Bush 9100, 1985
Cassette stuck inside.
Stretched band so not fully engaged tape.
Whine on playing could be due to mis-positioned 
Rec/Play link wire , also dropping out of play signal one or 
both channels.
Testing needs all cables connected except the aerial one.
Presumably cannot be turned from standby to power 
without the remote.

Bush MC A1/A micro audio
CD stops playing soon after starting.
Remade all solder joints at BA6898 and all 
connections up to the platter motor.
Survived me creating a solder bridge at the IC 
between the 2 output lines. What I thought was a solder 
bridge between pins 6 and 7 was a half-hidden power rail pcb track 
cutting this stopped sledge,platter and focus drive.
Probable cause was one of the header connectors 
so soldered 6 way lead instead of connector as a connector 
on either end anyway.
Sluggish tape rewind - replaced the second drive belt 
with a larger section one.
Whole unit comes apart quite easily and is workable 
on in dis-assembled state.
Curiously there was a hand scratched message in oriental script written 
on the aluminium faced cardboard under the CD processing board.

Bush MRC110 Radio /Cassette
Clicking noise in play 
Irregularity on the floppy intermediary cog,flexing 
making it worse. Bent the end stop to the activation 
radial arm so not deforming the cog so much.

Bush MC A1/A , 1997
No movements or laser light , totally dead CD player. Just -- in the
display.
Function sw and door latch sw ok. Plenty of 5V etc supplies around on the
chippery. Crystal and ceramic resonator have oscillation.
All 4 channel motor/focus driver o/p at 3.8V, all 4 inputs at 2.1V, disable
is set off ie operational.
Pressing all sm chip leads , no change
Swapping laser and carrier/motors section with another one laying around,
the same zilch. No dodgy electrolytics.
all BA6898 i/p 2.1V, all o/p 3.8V.
Failed to get it working, too old 
and basic to bother any further.

Connoisseur DB2 ,used 1.2mm Symel sleving , join with ex-bungee 
core cord, glued in with capillary superglue. Join piece about 5mm 
long pushed in each open end with a needle.
A cocktail stick useful for aligning
pulley and platten and hooking out the band from the platten if required to.  If 33rpm only and band drops off then
pull off and invert the pulley
BD1 deck drive band cut from 8inch silicone pie dish, cut down with PTFE and scalpel 
"bean slicer" to leave thickened rim only. Not round or fully square but as long as no twists 
it is fine. Bit too short and so tight , needs thicker motor suspension bands. Any rough edges to the silicone band will catch 
on the 33/45 flip of the drive pulley

Dansette Capri record player
With me for a straightforward repair. Uses UCL82 and UY85. While in there wanted to find a manufacturing 
date, any ideas where?
Only thing that seemed likely was a paper label with 69 in the number, but 69 seems a bit late for carbon 
resistors and dark brown flat capacitors and no solid state rectifier 
no sound
1M vol pot o/c wiper 
BSR C129-C-1
all Rs measure high
33K to 44K, 100K open circuit but no discolouration at all.
120 2W to 155R
15K to 18.4K
680K to 890K
3.3M to 4.8M
Running upside down nasty motor noise
pilot lamp replaced with 28V , 3.5W, no good
original had 1R ocross cold filament and only the very vaguest of light from it
6.2V,.3A
loss of output can be due to loss of wiper contact on the tone pot

Dansette valve amp record deck 1959 or so
"Bermuda" as Major de Luxe of 1959 , BSR Monarch deck
Had been in a loft for years.
Remove the 8 screws around the deck base and pull 
the metal deck through the hole.
Original Mullard EL84 tested good gain,no leakage, and all else checked out.
On powering there was amp hiss and crackle on turning the worn out vol
control.
But stroking the stylus with fingertip produced nothing.
Wiring between pu and vol control is fine.
Putting the output of either pu LP or 45 to a scope and touching either
stylus produces absolutely no signal at 2mV per division.
Make of rotatable pu Ful-fi
 , Made in England, number TC8S , and TC8C and TC8RS for the stylii.
Connected to the valve grid via 1M vol pot.
Let this be a lesson to anyone in the UK -
DO NOT store Rochelle crystal cartridges in lofts or sheds.
The crystal must be hygroscopic.
After removing the copper rivets (used flute section of small end mill to
avoid the rotating rivet problem with drilling out rivets in plastic) and
separating the 2 main parts, the problem was obvious.
I just managed to move the parts apart enough to photograph before the
active part fell to bits, lightly probing with a pin it was the consistency
of dusty paste. (1 mm graph paper)
http://www.diversed.fsnet.co.uk/ful-fi1.jpg
Left section is the cover, slid sideways, and the R section, on a nylon nut
for focus, is inverted, part of the "crystal" with angled ground strip that
touches the central pu pin (common to the other pu)  to the outside, along
with the signal pin for that pick up.
The other pickup , not seen yet, but will be the same state, is under the
central view.
The brown part is the rubbery material that engages with the crystals and
stylus shafts.
Plenty of copper carbonate corrosion inside.
The remaining parts of the yoke, styli etc
http://www.diversed.fsnet.co.uk/ful-fi2.jpg
I assume piezo-ceramic is not prone to this problem over 40 years.
I reckon it is possible to convert piezo cartridges.
I have dozens of later N.O.S Sonotone mono pickups, but have never looked
inside one.
http://www.diversed.fsnet.co.uk/ful-fi3.jpg
The central image is the active section. Not obvious in pic but the 2
vertical sections are each metal/piezo-ceramic/metal sandwich like bi-metal
strip in fabrication, set in quadrature, so a pair of pickups, but
electrically combined for mono output.
So although these are pinned out as mono, just rewiring the innards and
adding a pin would presumably convert to stereo.
Electrical contacts are via fine sprung strips set in a black rubber pad
like the white one shown, there is also another such black block removed,
they hold in place in the casing.
The lower creamish joining part is the plastic cradle/saddle for the stylus
shaft.
Cutting down the rubber pads a bit and sorting out some contacts and gluing
in the ful-fi casing will probably work, whether capacitance etc is wrong
I'll wait and see.
The kid's clothes peg, 1 inch long was just right as an insulated clip to
hold a pair of contacts, temporarily, to check on a scope.
The circuit is minimalism, as in the Newnes 1959 guide for Dansette Major de
Luxe.
A triple cap can, 2 other axial caps, 2 Rs, rectifier , 2 pots, EL84, mains
and o/p transformer.
I took another Sonotone apart. I had not lost a silver spring from the other
one, only one active element is used so 2 wires only.
I will try lashups as series and parallel trying to determine which gives
most signal/ most f range.
I decided to take a skew view before wiring in
http://www.diversed.fsnet.co.uk/ful-fi4.jpg
2 rings of green silicone rubber sleeving to take silvered wires before dabs
of gummy glue.
One black rubber pad chamfered to rest in the top cover, yellow-white rubber
pad cut down , orginal brown rubbery moulding that enclosed both original
rochelle crystals and extensions to both stylii saddles.
The saphire of the original remounted ( coded yellow and green) stylus is
just visible to the top and right of the brown section, through a gap in the
white plastic casing.
The original small plastic stylus saddle went quite neatly through the hole
for the original rochelle.
The now unused second brass screw mount for the other stylus and its
corresponding saddle rest flat, on the brown section, is visible on the
lower edge.
Decided to wire in only one active element of the Sonotone and also to have
more space to play with ditch the 78 option and just use 2 of the original 3
pins and plates  to the outside. It is very critical on signal generation on
how much the rubber supports are compressed, I may cut the thickness down a
bit if the sound is ropey.
It would probably be possible, in space terms, to separate the 2 sonotone
and mount one either side and retain double stylus, rotating function.
Decided as the original Sonotone was neatly anchored 
at the saddle end then mounted to try with just the 
black pad in place to avoid damping the piezo.
Googling for what a Rochellle crystal should look like I found someone else
has gone down this route
http://www3.sympatico.ca/belanger.eric/Radios/cartridge.htm
completely different internals
I had to abandon putting piezo element in the original cartridge housing,
not enough output.
Sliding a cable tie lightly and easy direction over the stylus gave about 100mV , wheras doing
the same over a complete piezo, ie vibration not having to go through a load
of brownish rubber gave about 2V pk-pk output with the cable tie.
Adabted the yoke to be able to slide in piezo pick-up ,retains the little
78/LP flag , and can rotate but no second stylus, and is shrouded in the arm
so nothing shows in normal use.
Nylon ring on either prong of the yoke, 
to engage with the Sonotone , bound with PTFE and 
swathed in hotmelt glue. On removing PTFE 
made a reasonable mount into the yoke held
by the original headshell part.
260R mains primary // motor, 350R + 0.6R (heater) 
secondary
Speaker 2.2R
o/p transformer .5R with speaker and 385R
Original cartridge 5gm , replacement 3.5gm.
Feeding 1KHz , 200mV directly into th evalve gave reasonable sound level.
Squeal on motor drive - removed the large ciclip to 
remove the platter and small circlip over 
rubber disc pulley and cleaned out.
Replaced the selenium rectifier with 1N4007 
mounted on a 20mm fuse holder as a standoff, 
as original was introducing a lot of hum.
Digression on trying to find way of testing 
Using 9V battery and 300 ohm dropper shows near enough 9V over the
rectifier, how high V do you have to go with a good one to check it ?
Single element rectifier
Siemens lazy S logo
Made in Germany
E 250c50
Kc 0.6e 11/16
1979 Siemens databook and E250C50 were still listed,
rating only 200V, 20mA
I removed and tried on a bench supply thru 330 ohms.
Took to 25V and read over the rectifier 25V, powered either way
So replaced with Si
At switch on the DC at this rectifier 300V 
dropping to 220V when fully on.
On removing/replacing the rear connectors make 
sure you don't short the bare ground connections to 
something.
The "stereo" output is just cartridge output , 
presumably there for a later 
up-coming technology of 1960s conversion to stereo cartridge

Dual C3430 deck
buzz on one ch
gn ground, red top inner pair measured 230K
Wh, Blue Gnd outer pair 750R
Probably due to someone twisting connector , then pin turns and internal wire twists and breaks. 
Maroon red stylus insert, cartridge just marked L,R and JAPAN on black connector plate plastic .
Dart needle under this plate to lever away and break glue bnd. 
Relatively stout wire between metal screen and green pin.
Seems like 4 coils inside , didn;t measure the wire diameter but used larger .15mm 
guage wire to repair the break. 

Ferguson 3T13 portable stereo
No mechanical tape functions.
Yet another m/c well past its use-by date that the owner 
cannot part with.The drive belt had dropped off due to 
one of the 3 rubber suspension grommets for the motor 
dissolving into chemical slush the remaining 2 would 
soon have gone the same way.

Ferguson 3022 record player, 1969
Rough speed and no bass control
Uses BSR UA 15 SS and X3M , pull formost clip to 
release cartridge.
Remove 4 deck screws, and hardboard screws. Slide 
mat radially to release from keyhole slots, remove 
circlip. 2 screwdrivers in 2 slots to lift platter off.
Old grease on speed change yolk interferring with 
spring return action, also added a turn to the spring to give 
35 gm of action on the end of the radial arm.
Cleaned jockey and motor spindle, 
only remove 3 (not all 4 ) screws on the motor.
Liquid spilt into bass pot.
Mechanically held fast to pcb so desoldering is 
difficult. Untwist side retaining lugs first. 
Removed and renovated but cut a slot in the 
metalwork before re-assembly and ground down the terminals a bit.
Uses motor windings as mains transformer.
Mark the different types of screws.
After a few hours re-use the output level dropped 
and the sound became muddy. BSR X3M cartridge , 
ground off rivet head. The plasticizer had leeched 
out of the blue rubbery suspension block and the 
resulting gloo was getting into the mechanical 
contact between piezo element foil tails and the 
outgoing connector tails or coating the piezo 
or both causing the problem. Replaced with Sonotone 3509M cartridge.


Fisher FM-M75 tuner of a M70 system
Intermittant loss of station
Not enough clearance between front panel switch pcb and 
the fascia intermittently allowing the channel 1 switch to activate 
so pack out the standoffs a mm or so.Also the display lamps needed 
changing but requires 16V lamps so bodged up with two sets of 
seriesed 9Volt lamps

Freeplay Freepower Bayliss South African 
clockwork radio ,
no tuning possible.
Dial unscrewed from the tunning cap.
Due to mangling of polythene sheet dialectrics 
crumpled up inside so it looked like crazed plastic 
on the tuner clear plastic casing.
Presumably shorted vanes on AM .
 FM tuning was ok.
Fixed dial piece back to the shaft of the 
tuner. The recess was ground up so had to melt 
2 pins into the remaining plastic to mate with 
the flats on the brass shaft.
Didn't bother replacing or remaking tuner cap 
as only a crude radio.
When dismantling only remove vol knob, the 
tuning knob is set from inside under the 
'dial cord' mechanism. Also the aerial was broken. 
To access this area requires removing the clockwork 
generator. Before removing cogs hold back the 
residual torque even when run down.
Presumably this generator is demand led in effect 
via motor/generator back emf/torque. High output 
the 'escapement ' runs round fast and slow for 
low level or off position.
Extra electrolytics may be useful as output 
is highly erratic - well on this one it was.
Radio uses Telefunken U2510B IC

Gemini PT1000 vynyl deck 1997
Cosmetic copy of Technics SL 1200 /1210 . Never mind the quality 
feel the weight -big lump of steel in the base . Powered up but failed 
to rotate platten after being moved between premises. Owner lifted 
off the platten and changed 230 V to 110 V and blew the fuse. 1 amp 
fuse blown in IEC socket. Replaced with 160mA as only a 20W 
transformer inside. Back to the original problem changed the on/off 
microswitch but probably only needed packing out between knob 
and switch lever.
With platten removed but running set on 33 moving very jerkily so 
could turn upside down. DC Voltages on main microprocessor board 
ribbon cable were 0,10.8,6,.1,.1,.1,2.5,0,.1,.1,3,2.8 to 3.4 varying,5V


General vinyl deck problem.
New owner of deck reported signals ok but hum problem on both channels.
Mag cartridge but DVM reading between signal and shield 
of infinity. 400 ohm between signal and sheilding of other channel 
and vice-versa. Someone had crossed the wires between cartridge 
output and tonearm connector so neither signal line sheilded 
inside the deck.

Goodmans 2725R 3 CD midi 1999?
Loss of one channel on radio and much later total failure.
Radio problem probably at manufacture , the radio o/p lead part 
guillotined , screening wires half cut and most of one 
conductor cut so eventually one remaining filament failed.
One 2A fuse blew because of failure of one 1N4002 bridge diode.
TA8216H uses a 1000uF,25V to block DC on each speaker o/p.
4052 for function switching? on power board 
with 7812 (15 ohm or so to ground normal), 2SD882 and TA2078.
Mark all lead plug/sockets before removing
The mains lead/transformer  joint is as manufacture.
Remove 2x3 side screws to remove phono deck
Remove 2x4 side screws to remove CD unit

Goodmans 4460 mini hifi 
CD drawer not working and failure to skip tracks
Excessive lubricating grease on the gear train to 
the tooth rack had splattered upwards onto the rubber 
drive belt,so cleaned and replaced belt.The Cds would play 
whole side but not be able to skip one or more tracks.The 
final part of the radial positioner is a plastic tooth rack held 
by 2 flimsy strips of plastic to act as a week link,at end stop etc 
the rack would disengage from the pinion.I suspeced weakening 
of this plastic rather than build up of friction on the laser carrier.
Straightened out some small spring wire and fixed 2 lengths 
to the existing 2 plastic mounts with hot-melt string to beef-up.
To align tray mechanism hand crank the gears until the tray is in 
and the platten clamp is about to move is where the tray is 
free to move in and out disengaged from the rack.

Goodmans CM80 approx 1968-1972 music centre (no ICs,2 AC138 brown 
rectangular and tubular Rs and Cs).
Lenco Swiss transcription deck that is 
half the weight of the whole unit.
Crackly volume and rubbing tuning knob.
To remove top undo 4 + 1 wood crews on base.
Tuning prob was sub plate behind front pannel out of register with 
tuning shaft and filed back.
To recondition dual and compensated pot,demount,bend 
back 4 alloy tabs at D shaft end. Remove associated 
track. To remove other cover use a heavy duty point 
such as an old dartboard dart to prize back 
the relevant 4 tabs.
Someone had previously replaced 2x MJE2955 with TIP43C 
with swapped legs on one channel and no problem there.
Grundig C9000 old portable radio /tape.
Blown pass trannie in ps marked GD 361 which is Grundig 
special 22V,4A. Replaced with BD787. Balance control worn 
out. Made by Preh very odd single track pot. 0 to 40 percent of 
track 200K ohm ,40 to 60 pc insulation then 60 to about 100 pc 
200K. Wiper pin not centre pin.  Dismantled and wiper not very flexible and contact 
had totally worn down tracks. 
Cut one of the wiper arms to reduce springing 
and bent contact to new part of track. Small 5mm 
black plastic 4 pinned IC marked 720 in ps probably dc to dc 
converter for tuner pin 1 9.5V,pin 2 0V,pin 3 33V,pin 4 9.5V.
To refit body to case move the tape type slider to mate with 
innards.

Goodmans CM80
Very low level sound on one channel and then 
distorted if increased the vol. All DC levels match 
between channels and DVM tranny checks ok but 
lack of charge hold on large electrolytic.
Failed to o/c 3300uF,40V capacitor between speaker 
line and junction of the 2 low ohm/high W droppers 
that look like silvered mica caps. Don't know if over-heated 
or plastic/plastic welding over time but the cap 
plastic covering was 'melted' into the P clip.


Headshell connector problem.
Vinyl deck headshells - severely corroded wires 
and absent connectors for the 4 wires connecting to 
the 4 pins on the cartridge. The only replacement for 
these channel profile connectors I could think of was the phosphor - bronze 
sliding contacts inside of basic slide switches. 
Broke apart a few such switches to rob the contacts. 
Slid on the shaft of a jeweller's screwdriver and cropped 
off the contact section to leave a channel and soldered 
fresh coloured wire to one end

Hitachi SDT118 music centre
No tape transport.
Misaligned leaf switch in line with the motor 
under the tape unit .

HITACHI TRK 8080
Intermittent loss of one channel then no transport
Someone with sentimental attachement to this 20 year old
ghetto blaster wanted it repaired.The channel loss
was due to corroded/distorted contacts on the phones jack socket and the 
motor was totally defunct.This mechanical
flywheel governed motor was replaced with an electronic governed motor 
with direction reversed by cutting tracks and reversing the leads to the 
actual motor and a change of pulley 
as well as adjustment of speed pot to get the right rpm.

JVC RC X620 Ghetto blaster
Intermittant then permanent no mains useage.
Yet again poor soldering on the mains/battery 
diverter switch in the mains socket.Note some of the 
ribbon cable connectors on this m/c are push to release and 
others pull to release.Without all main case screws in place 
the tape cassette flaps will not lock down onto the decks.
Lightly filed both motor rubber drive pinion surfaces.

JVC RC828LB ghetto blaster,1977
Motor boating noise on one channel and to  a lesser extent on the other. 
Due to excessive build up of black (copper sulphide?) on the endmost static 
contacts inside the input selector switch so braking contacts. 
This seems to be an ever more common occurance for old equipment kept 
in the acidified air of the UK for 30 years.
Label the wires to 
the battery compartment when removing back. Unhook the plastic 
pivot connection to free the main board from the selector switch mechanism. 
Reconditioned the slide switch as per tips file. Problem closing the cassette 
flap due to wear on the take-up drive dogs allowing the spool of the 
tapes to catch on pillar of the take-up spool. Reduced the strength of the 
spring that lets the slidding drive dog push along the pillar. Heat on 2 
bits of heatshrink sleeve to the bottom pivoting cassette carrier to 
raise the cassette a bit and toughen / bend back the 2 side springs to ]
keep the cassette seated against the deck in FF and REW.
Then 2 weeks later someone else with the same model needing repair. Again 
intermittant problem with the function switch and same black corrossion. 
Also problems with the phono sockets ,all very flimsy ,could 
only sensibly repair by wiring in some replacement satandard 
phono sockets in another part of the casing.
While in there in FM radio mode 
DC voltages on HA11251
3.6,3.6,3.6,5.9,0,3.4,3.5,4.8 / 0,1.4,5.8,1.2,0,3.2,1.4,.7
AN 362
2.6,1.7,1.7,1.7,1.5,1.7,1.7,.1/ .5,0,.8,2.6,2.6,2.3,3.2,7

JVC RC838 Ghetto Blaster 1981
All sorts of problems due to spilt liquid.
240/110 V switch mounted not too obviously 
at mains inlet.
Remove back then 9 internal screws
and knobs to remove in one piece 
the speakers,front and 4 sides to expose innards
All switches and sliders needed taking apart 
and cleaning. The Man/ Auto switch fouled so 
no record signal in tape record function. 
Same with the gummed up tape counter.
Tape door return spring on wrong side of perspex 
lever so flap would not open. Design flaw 
means the tuning string rubs one of the chassis 
pillars. Wire at back of one condenser mike corroded away. 
No reliable tape transport function due to loose slip 
clutch with crack due to steel/ plastic expansion . 
Loose in 2 senses ,free to rotate on the steel shaft and free 
to slide so binding against the holding arm. 
Rotation meaning loss of torque at tape ends and sliding 
/rubbing leading to intermitant tape stop at any point.
Marked the clutch position and demounted from 
the arm. Then with double action end 
snips held angled to the shaft in marked area made series 
of cuts into the steel then in reverse sense to give 
a crude knurling effect. The plastic slip disc would then 
locate positively on the "knurling". 



JVC RC-W210 ghetto blaster
Snagged tape,wrapped around pinch wheel
Too much axial play on the drive spindle allowing the 
cogs driving the take up reel to disengage so removed plastic 
circlip around spindle and packed out 
with a couple of small running washers,modified the second tape 
unit in similar fashion.

JVC RCX720 Portable CD/Tape etc
One channel only for 10 percent of track of volume control
To desolder the pot it is necessary to remove the LCD display 
board which disengages from the main PCB in direction perpendicular 
to the face of the LCD.Dismount the pot section from the motorised 
section. Fault due to slider prongs bending away from the track rather than 
worn track

JVC R-S33L tuner amp
Failure of one channel
One of the HA1457 SIL preamps had failed at the rear
of the graphic panel.

Marantz TT2000 record deck
Irregular speed
To work on this deck upside down stick some tape around the 
central spinle of the platter,the inertia of the aluminium 
is required for proper running of the motor.The fault 
was a broken contact in the speed adjustment pot so 
affecting 33 and 45 rpm setting.

Murphy (no apparent model number) portable CD/Tape/Radio
Worn out tracks on all pots,vol,bal,and graphic.
At least with these un-enclosed slider pots it is an easy job 
to put a pin in between the double slider contact fingers to open out 
to use a new section of track and lubricate.

National Panasonic SG 2080 ,old music centre
Loud interference on record.
Failure of the long ,play / record function switch

Numark PT-01USB, 2009
no LED or function, corrossion on battery contacts.
LA4261, LA5526, 
8R 4W sp
7809A,27R, 2x 6R8
BA033, PCM2900E, 074, xtal 2M
disconnect CN1 and CN2 but needs TE12 in place to test on the bench with a 9V battery. 
As line power is 9V ac then external 12V car battery may work.
Negative batt termiunal springs needed pulling out as well as corrossion grinding 
off and solder "plating"

Panasonic FM15 tape/radio
Poor switch contact on the wave-band switch.
For short term squirted switch cleaner inside the 
mechanism and for long term formed one end of a 
tension spring around the black plastic actuator of the 
switch and anchored other end to a part of the pcb to force 
the sliding contacts to one side to make more consistent 
contact.

Panasonic SA CH 74,compact hi-fi 1996
Broken mic plug stuck in socket,jammed CD mechanism
Mark orientation of all removable ribbon cables before 
separating - foil type push and pull,wire type raise the surround 
before pulling on the cable. Pull front panel away from main body, 
2 indirect connectors under the vol control.
To get to mic socket ,remove 2 knobs ,remove display 
pannel then multi-switch pannel.  Desolder socket ,drill small hole 
on underside and push remnant of plug back.
This one has 5 separate platters to hold each CD.
On entry the CD sldes along the bottom ,is elevated by the laser + spinner
assembly and 4 flimsy 'ratchet' pawls hold the carrier in the elevated
position and the main slide mchanism returns the carrier to the top of the
stack of 5 after playing or along bottom to release/change through front.
 As a fall-back ,disabling the
pawls and associated high level slideway the carrier will move in and out at
low level for single CD operation without jams.
Unfortunately a flimsey microswitch monitors carrier across the top and i
won't know what effect non-switching of this micro will have until i
rerassemble it all.
Marvellous array of mechanisms all coming off the one motor drive . 
What sort of mind designs these mechanisms, rotary,rack and
pinion, latches, compound slideways,translating and reciprocating motions?
[ for anyone involved with this sort of thing or automata then 
this book may be interesting
Ingenious Mechanisms for Designers and Inventors
Volume I: Franklin D. Jones; 1930, 536 pp, illustrated, ISBN 0-8311-1029-5 ]
Retrieved a displaced   torsion spring from
elesewhere in the casing. This biased a latch (at the rear) that engaged / disengaged at
the point where CD carrier sliding along base changes to vertical movement of 
the laser + spinner and carrier.
It looks as though a physically large but not strong torsion spring ,now
missing, used to be at the
centre of a long lever and quadrant cog that drives a lead screw to push a
lifter of all the stacked CDs.
Could not make sense of this spring, as to function properly ,seems to be the
reverse action to what the anchor hooks would suggest.
Finally under the front edge of the CD carrier slideway is a little passive
latch that holds/releases
the bottom-most carrier relative to the slideway. Fingernails pushed behind this 
cover and forced up and out will release it.
This latch ,not obviously as
covered,was out of alignment because the central plastic pin was broken-
replaced with glued in nylon bolt after drilling a hole . Broken pedastal 
type of microswitch monitoring slideway limits.
For these 2 uswitches with CD drawer out both are s/c,
in between sw1 s/c and sw2 o/c. Drawer in both o/c.
2 uswitches monitoring laser carrier movement in play 
sw2 &sw3 s/c ,in between sw3 o/c,sw2 s/c
at bottom position sw2 & sw3 o/c.
Top slideway microswitch n/o
Drawer motor 3 to 4 V for external powering or 
remove rubber band and turn large cogs by finger.
On re-assembly intermittently powered down showing 
error F61 or FG1 ,probably dodgy ribbon connections as 
remade all and ok after that.

Panasonic SG5090 monster music centre of 1978
Wavering sound on tape both in volume sense and sort of cross channel 
effect. The erase and tape/record heads have a plastic submount. The erase 
is anchored to the chassis by both screws. The main head for some unknown reason 
has the adjustment screwed into this plastic and the fixed one into the metal. 
The plastic had broken away. Dismount and fix a matching 2mm nut to the screw and 
glue into the plastic with bracing from a solder tag over the nut and glued into the main plastic. 
Use a shorter spring for the adjustment of azimuth.          
The scale side-illumination festoon bulb 12.6V,.38A was o/c and no replacement available. 
Made up serised oblong section LEDs in a bank of 2 by 3 giving a somewhat pleasing 
red illumination even if lower brightness. Broke open a barrel fuse and soldered 
an end cap to each end of this bank of LEDs to mount in the existing bulb holder. 
Perhaps should have added another 2x3 set 
at the other end of the perspex as plenty of power of course available compared to the 
original 5 watt bulb. 

Collaro RC457 record deck from 1958 Philco A3762, ser no. 1267**
under mat ref no 5809 presumably date code
To remove the mat, remove circlip , then remove platter and push 
the 3 rubber stubs from inside, don't pull the mast off the platter as nibs ar ewider on the inside 
i have the schematic but mechanical problems
Would there have been a rubber tyre on the rim of the left hand drive pulley , shown in this pic , half way down
http://www.lencoheaven.net/forum/index.php?topic=11426.0
right hand one is for PTO use.
Perhaps red rubber like the platter mat (I remember replacing a perished/hard/split BeoGram drive tyre that was red)
The images shown above have a hint of a circular mark set inside of the rim proper, both sides , as though something was fitted there at one time. This one has the same marks but no sign of any tyre inside (someone had been inside under the platter so perhaps they disposed off remains)
Dated from to 1958 and Blackburn from 2 original Mullard UCL83 coded
mG1
B8B
and perhaps rubber stamp mark , under platter mat of "Ref No. 5809"
I've added a stretched strip of bicycle inner tube over the rim as a soft rubber tyre, (gum glued and squashed in place) and .5mm compensation padding washers to get the 45 and 33 rpm speeds working, previously just the 78rpm working. Otherwise swivel-linkage metalwork bottoms-out and would not make contact between stepped drive "cone" and platter rim interior, without added rim or perhaps due to hard rubber disc shrinkage .Still no 16rpm but no problem with that.
Is there  a tutorial somewhere on www for the Auto mechanism as it has the promise of working but temperamental, sometimes does the reverse of the selected function 
http://www.diverse.4mg.com/corrola1.jpg
Red "A" mark the gound surfaces that mate with the sintered metal cylinder attached to the platter. Between them is the cast metal surface , recessed back a few thou/mil with a countersunk hole and then a tapped hole inside. Some sort of closure to keep oil inside but bleed out to a missing felt pad ? I don't think the hole passes through to the core that carries the mult-disc changer linkage, ie sealed to oil seepage to the interior 
I think the record size determination is the little metal  "semaphore" arm that sticks inwards from the large post. If it leaves the arm untouched then a single, if 12 inch then it moves the arm down and that cross-links to the tonearm-drop mechanism, 78s don't know , perhaps manual for them, 1950s anyway not 1930s. I don't think there is a cross-link to the speed change system.
The original rim surface of the drive disc is too rough for driving the platter, I would have thought, perhaps originally it was as smooth as the PTO one but breaks up in use like cassette tape pinch wheels, or tyred of course. 
The info here
http://www.vintage-radio.net/forum/showthread.php?t=68177
http://www.vintage-radio.net/forum/showthread.php?t=46456&highlight=collaro+conquest
is very similar model. 
I don't know how many times I've picked up this deck, but it must have been always the same way round. Until this morning and on the other side of the main stem is an exactly similar countersunk hole with a small screw in it. Must be for fixing 2 cylindrical parts together. Other than checking for tightness I don't think I'll fix a screw in the other side , as there is perhaps a liklihood of them loosening over time, unless it turns out that it gives the mechanism a malfunction with only 1 fixing 
All that mechanical rat's nest is now working, except for 16RPM and have not tried stacking records (I've only one single for test purposes) but the hold and drop mechanism works for one and clamping arm, last record height sensing, for final eject works.
Now to fit 3 core earthed cable, someone previously had connected record deck metalwork to mains neutral, not just the isolated lowside (theoretically if house wiring is standard) amp chasis 
Deck run off the mains at near enough correct speed (shaded pole type) counting revs in a minute.
Try with the amp and very sluggish. Looks as though the deck could never have worked as is. The schematic shows 160V ,.1A motor used as a dropper for 2x 40V valve heaters and 3.5V pilot bulb for 240V mains. Perhaps someone changed the motor back in history to the present 240V, 14W one and gave up.
The only way to run this is add a dropper for the heaters and rewire the motor direct off 240V 
For 16/33/45/78rpm , stepped cone diameters 7.15mm/12.7/5.75/2.6/11.4mm ? (jumbled notes, 4 of these readings)
PTO disc comes off 45rpm , 63.3mm diameter
platter 240mm inside diam
platter jockey 63.5mm
inner tube 80x18x1 mm stretched over night over a small vice to 120x15mm , stretching to 280mm 
becomes 64.8mm diam ove rhte pulley, next time fold the band in half 
before stretching overnight, hopefully leave a crease that will centralise the rim 
before gum gluing in place and squashing flat in a vice
motor very sluggish. 2 sc then oval spring plate holding a felt anulus in place, disc to receive 
spherical housing , under it a pad , ball bearing in oil. Beware of ball falling out as only held by 
compacted grease, same with small Al disc at the bottom. Cleaned all including 
pads with meths then light oil including pads
2 tension springs fitted to pin from motor
reclipped loose free end over swing arm hook, part of speed 
change mech. 5 springs in all for that mech.
If run upside down then deliberate? nasty noise
Plastic tone arm , needle heated via soldering iron, easily punctures a web underneath
HMV 2004 maybe similar
2W 100R carbon R to Se rect
505R motor coil 
1.M across pickup wires
other Rs
330K
680K,2K
6K8 2W,330K
270,560K,10M
?10? perhaps a cap
220,2K2
220K,220K
560K
3K3
50, 1M
Pilot lamp 3.5V .1A seaized in
Flex lamp holder arms with pliers and then initially at pip end pliers to twist
.5mm washer added to jockey spindle to compensate for tyre
TO220 mounting plastic washer placed over the central bearing to take the fixing sc.
with 240V supply and 110R in line 10.4V dropped so 94ma 
and if stalled rises to 100mA
Goldring S17LP , saphire point
Drive not always present on 33, 45 ok.
Tied 10 coilds of the relevant spring with a loop of wire to tighten 
the spring
AC53 marked motor, 240V ac
Clean core of sintered metal bearing with a merkin of cotton wool.
.3mm diameter difference central area to ground surfaces, central section 10.5mm
finger rubbed across the stylus 20 to 200mV on DVM
To adj stylus weight , G screw on tonearm , increase weight by turning anticlockwise. 
As found was 5gm , measure with the stylus at normal play height as "weight" set by spring tension
If clamping arm is in place over the spindle then auto reject. If swung out of the way 
then will cycle into play again. 
If the arm is propped up over the spindle, simulating a stack of  records then will recycle.
33.5 revs in 1m 03 sec, so slow
To avoid resetting the semaphore arm each time a 1.5 inch rubber drive band 
over the pillar to keep the arm down
Disconnected neutral connection from mains, from the deck frame gnd. Someone had been in there before  and changed mains wire 
to bell wire.
3 core replacement, steam iron black and white textile covered , sypathetic with the era and black mains plug.
Crimp connector pair added  at inlet earth for new earth wire to deck at the tag board mount
To open casing hole, heat rexine neasr it and peel back , then round file/rasps.
No electrostatic speaker, on schematic, no trace of one in this unit.
The wiring under the tonearm is at mains neutral , so needs shrouding off.
May try swapping to true gnd but probably will introduce mains hash
3 existing metal downward protrusions of the mechanics inside allow good support on the 
bench , when outrside of case and for testing.
Tried 16RPM with another thin band . just stretched over my replacement tyre and 16RPM 
worked till it dropped off. So for 16rpm perhaps needs a 2/3 mm band over the pulley then the tyre placed over. 
124R dropped to chassis via bulb and 2x heaters, 40V each.
Motor plate says AC53 200-250V 14W.
So only about 150V over motor. Seems to be a pair of empty mounts under the chassis 
over the "vent" to take some sort of dropper to drop 160V ,.1A 16W
Removed hinged lid to make access easier here
Used 3 x 5K6 w/w paralled as dropper of 164V ac. Ceramic terminal post fixed to a thru chassis hole, reposistioned the wire 
through it elsewhere , and 2x cups and washers to suit 
the small mounting bolt size.
Clipping type distortion of amp (did not try isolation Tx and scope to see for sure). Measuring rect DC to chassis , 70V only dropping to 66V as valves come on and still dropping.
Same with 220uF 385 cap placed across also.
Replaced Se (SenTerCel type c2D datecode? D57) with 1N4007 slung under the chassis.
With the original cap only measured now 245V dc at that point.
Se rect and wires removed and also 0.1uF plate cap
2.9V simple DVM-Vac on HT1
sp 3.3R
Discovered electrostatic speaker , red and bn wires going under sp surround , so coaxial to the cone.
Mains sw pot loose, corroded push on circlip type bush nut, standard thread for replacement.
Remove front Philco cover from 2 screws at rear, last part to return on removing front board with amp and sp.
8 wood screcessed and angled
Tx primary 0.6R
Small output impedance matching transformer for 7W output, DC resistance of primaries measuring 
746 and 350 ohm , inductance 1.95uH/2.1uH, would that amount of winding resistance disparity be expected? 
Electrostatic sp signal off V2 , not V1 on the schematic, marked 
Colibri Ges. Gesch , HT 64 Made in Austria
Replace large carbon 100R 1W with 120R 2.5W vitreous for fire prevention reasons
Soft half-wave distortion of amp , unbalanced but not unipolar
V1
77,-.7,0,0,-.02,190,27,173,28V dc
V287,9.5,31,-.02,-.02,214,27,172,12
from schematic
V1 70,?,0,?,?,217,13,203,?
V2 137,<64,65,4?,5?,<225,13,203,?
560K R to V1p9 measures 200K one way and 2.5M the other
look wax covered caps , replaced
1000V 2nF disc ceramics replacing 
TCC Plastiseal type 393
10mV 400Hz (600R source) full vol, 0.33V 
over the speaker
with higher speaker electrostatic speaker output higher than 12KHz (top limit of my hearing)
now V1 91,0.9,0,0,-.01,262,16,244,.006
V2 161,29,72,-.01,261,16,245,.01
HT2 271V on mid Tx )
262V on each end of Tx now
Removed fan from motor to lubricate bearing with molybdenum oil/grease.
Made no difference to sometimes running at half speed. Found no way round this , 
presumably skipping poles, owner having to push platter by hand at start up to 
bring up to speed.
Pilot bulb not over the light pipe. Pull the clamp off the chassis stub and put a 1/8 twist in the 
flange and bend down , so the bulb is over the pipe.

Philips 22DC752  (752) car radio cassette
Jammed tape
Yet again an example of that silly band of plastic around the periphery of 
the main drive pulley was broken and jammed  (presumably 
differential temperature change of plastic and metal).
Remove all plastic,mount the pulley on a suitable block by 
drilling a few holes in the pulley,bolting, and centring in a lathe (the spindle 
is only mounted in a plastic insert so robust mounting is required).
Cut a groove in  the edge of the pulley..Compensate for change of diameter by adjusting the drive 
motor speed regulator.Similar fault on a Philips VC 600 ,how many 
thousands of these Philips units have been junked because of this design flaw.

philips aZ 9020/05 Ghetto Blaster
Intermittent power failure.
Bad solder joints on mains input socket/ 
diverter switch and pcb.

Philips AZ9712/05,1991
domestic hi-fi basically a thicker case around a restructured 
ghetto blaster. Junked but some info here
16V ac transformer
Release side panel on front button control side to access.


Philips ND 7500/05S portable cd/cas./rad
Door closure problems on CD and Cassette
Puny plastic bow-spring on CD flap closure had snapped. Find a 
light guage small compression spring that can wind on 1 turn 
onto the shaft of the flap closure nib allowing free end to 
bear against the back stop.Then hot melt spring to plastic shaft.
One of the cassette doors had broken away but solution is applicable 
to most cassette units. The 2 plastic pins at pivot points on L and R 
side of the flap had sheered.Find 2 (in this case different sized) 
washers that will give a clearance fit to the static bosses on the 
main body of the unit. With door flap removed from the m/c hot-melt 
glue these 2 washers co-axially to the pivot axis on the L and R 
and reintroduce to the main body. Not enough space now to use the 
original torsion spring (that opens the flap) so either a long tension spring one end 
looped onto the curved arm near the pivot after making a small hole in the top of 
the arm to take the end loop of the spring ,taken round the pivot 
with some small diameter polythene tube surrounding spring in this area 
and the other end fixed to body of m/c.Alternatively a small compression 
conical spring as used on -ve terminal of battery boxes glued to 
the inside of the tape deck to bear against the tape carrier when closed 
will give enough opening to allow fingers to open the door.

Curio,antique - Phonograph cactus needle sharpener?
http://home.graffiti.net/diverse:graffiti.net/cactus.jpg
Based on parallel jaw action pliers (mm scale)
Not many cactii in Conn I would have thought. At least no one tried
sharpening a steel needle with them as the mini guillotine blade is not
nicked at all. No patent number but inscribed on the parallel jaw action
Markings either side of the central pivot, out of focus in the pic
The Wade No 2 W. Schollhorn Co , Newhaven Conn.
Bernard's Pat , May 6 1890 (and manufacture ? date ) Jan 1 1901
Slightly raked guillotine blade under the "V" and needle? holder marked "H"
,triangular section, so presumably triangular cross section of needle.

Pioneer Hawaiian , 1960s portable record player
pic of similar here,
http://farm2.staticflickr.com/1267/4701108988_fe2868f377_z.jpg
Particularly any pickup and speaker info
Not powered up yet, just cold checking at the moment, I'm informed its not
working.
Nothing active inside , 10 ohm resistor , speaker with 2 coils of 36 ohm
each ?
6x 1.5V batteries
Nippon Chemi-con electrolytic 500uF, 6V number on it 056313G , datecode 1963
13/52 ?
The slide sw in that pic is rotary speed change sw 45,33 and power off on
this one
The pink deck plate is hardboard with the dimpled surface under. The 2 pots
are wire-wound 310R and 42R in circuit.
What I would like to know is what is the cartridge, 3 wires to it, one wire
to battery negative of seriesed 4 making 6V , and only that wire, so the
current of the 6V passes through the cartridge.
The motor is probably from an isolated 3V pair of batteries.
There is a cardboard strobe disc on the platten , for 60Hz countries but it
is now in 50 Hz UK
pickup, mm scale
http://diverse.4mg.com/hawaiian_pickup.jpg
pickup wires now desoldered
Resistance of yellow lines to frame black, wavering around 10K and 50K,
touching the stylus with a few gm of pressure and the resistance changes a
lot.
Speaker frame 77x77mm , marked
Pioneer
B
JGQ
2mm spindle of motor is pivotted to touch inside of "tyre " on inside of the
platten , rubber tyre 87mm internal , 91mm outside.
Speed change by resistanc ein line with the motor
carbon granular pickup?
The pillar under the stylus arm ,
that is the only visible part, is matt black in colour. The wavering
resistance reminds me of an attempt to use IC packing anti-static carbon
foam as a touch sensor for a robot I got involved with.
I could not take any sensible readings, all below are wavering values.
Tone-arm self weight at stylus of 15 gram, one pair of wires and reading
6.8K , add 2 gram and drops to 5.8K
but another time goes from 4.5K to 5.9K adding 2 gm.
Tapping the arm and reading goes to 50K. Looking at the rod under the stylus
it looks like carbon arc rod, compressed carbon with binder, not bakelite or
painted material
some more pics
http://diverse.4mg.com/hawaiian_top.jpg
with platter to the side
http://diverse.4mg.com/hawaiian_under.jpg
The 2 yellow ones to the pickup are desoldered and loose but go to the
speaker which has 3 active terminals , 2 coils, the fourth is a dummy I
think, used as a mounting post for the electrolytic which is in the motor
circuit. similar to 
http://www.rfcafe.com/references/electrical/NEETS%20Modules/NEETS-
Module-12-1-31-1-40.htm page 1-38
speaker instead of Tx. Centre tap returns via switch and a pot as well as a
battery back to the third terminal on the pickup
Abraided back to brass and solder film over .
corrossion on switch contacts and some battery contacts and some gunge on the active running surface of the platter, 
fold back the paper binder brass split pin "rivets" to remove the battery holder to get to the 
circlip of the platter spindle.
All I can say is it now works , hi-fi it aint. 


Pioneer PL320 direct drive record deck
Erratic speed
The pitch change pot needed attention or replacement. 
To remove the top cover around the tone-arm mount remove 
plastic plug at rear of tone-arm and undo the hex bolt to 
remove the rear extension to the arm

Pioneer SX 700 Tuner amp
Cracks and bangs ps fault
Dry joint on 2SD525

Portogram Mark nine 
old dance studio record player and amp,
Ser no 978*
fails after 1 hour of use
undo 3sc undr front to remove prea
Release 4x nuts and nylon, to remove Lenco deck
2 front nuts then lift enough to release the rear pair
Lenco L75/5, dated 1968? paper label saying  oz48**
Clean deck sc with 2BA die 
Heat sc on brass bearing tube and undo enough to release platter, label 
under, beware of ball bearing dropping out, if turning over
2 nuts art rear and remove sc under, to remove PA
Someone had replaced TO3s with 1981 dated 2N3055H.
Temp compensation using half a bridge rectifier in appearance , 2 diodes 
in a mount
2x .47R 2W, BC142,BC143, BC107A, preset in series with 2x diodes
cold solder joint on 1K2 cause of problem.
One pin of TO3 very close to chassis , bend away.
PREA 20V output to microphone section , 
blue test signal ther ok, but failed BC549 in main PREA , one junction o/c

Repairing vinyl record decks.
Before looking at the innards remove the cartridge or at least the stylus, tie 
the arm to the suport rest/pillar. If not positively held also remove the platter.

Samsung SCM 8250, music centre
CD s often not playing, showing No Disc.
When it worked then whole CD played
Dealt with the usual suspects.
Removed top clamp and tried with a 
heavier magnet clamp spinner 
while checking for laser o/p and focus/tracking action, 
then glued an 8gm 
washer to the original, cleaned lens with meths then 
cleaned off excess grease on innermost 
part of sled rack. Undid screw near the drawer 
motor , lifting CD unit and propping 
up the sliding plastic piece to give 
space to clean away excess grease that was 
likely to get on the band and replaced band.

Sanyo MCD Z10F CD ghetto blaster
Intermittant failure of fm radio.
Dry solder joints at either end of one of the small 
fixed 4 turn rf coils next to the tuner cap.
Due to the thick guage of the wire for this coil 
and its inherrant heatsinking the original (flow-solder?)
soldering had been inadequate.

Sharp CMS N50CD midi
No display illumination and erratic CD drawer.
CD draw motor drive band accessible via hole in carrier 
when half open/half closed. Use hooked probes to remove old 
and intrioduce new drive belt.
To save dismantling all the main board to get to the CD 
display bulbs. Fed 2 12V small bulbs from the supply to 
the tuner display bulbs and illuminated through the pins to the 
LCD display from the top edge.
Similar for the tuner LCD but as pcb is easily removable 
pushed bulbs under the outer edges of the display 
and glued all 4 in place.

Sharp GF570E Ghetto blaster
Neither tape playing
The drive pulley tyres on both tape units
were split and missing

Sharp QT 250 portable stereo
Intermittant loud oscillation like mains hum on one channel 
A nasty fault as you first think a break in contacts on the R/P or 
function change switch.These ok so perhaps one channel 
down on the SIL dual op/amp but ok.It was either the tiny 470uF supply 
smoothing cap to the op-amp that was intermittently causing 
problem. Plenty of space to replace with more spacious cap.
Also replaced the feedback 33uF cap around the op-amp with a 
lower value as the principal frequency of oscillation was perhaps 
10 or 20 Hz.

Sharp VZ1560 music system
One channel gone,mains hum power with button on or off.
Owner fiddling with speaker wires had knocked out half 
of the STK4332S successfully replaced with a STK4332. The ZIF 
ribbon socket on the power board is the push to pcb to release 
type.

Sony CDP M29
Tuner losing memory so replaced the malfunctioning 
.022F capacitor with a larger one on the other
 side of the pcb ,cutting away part of the shielding plate.
One of the tape function keys sheared off so 
remade with cable-ties as in tips files.

Sony CFS 210 ghetto blaster
Audio fades after 1/2 hour
Replace LA1260

Sony CFS 220 portable stereo numerous problems
Troubles due to a tinkerer messing around inside.
Symptom:Mangled tape because take up spool rotating wrong way.
Tinkerer had put the long drive band on so both capstan wheels were rotating in 
the same direction,one should be clockwise and the other counterclockwise.
Symptom : Main Slip clutch,auto reverse problems.
This clutch assembly has a distinctive 2 sides of a square of white 
plastic. When reassembling one side of this square is located between 2 
stand-off parts of the back plate and not located in what looks like a matching 
square recess of the main black plastic swing arm. Also when dismounting ,the sintered 
metal bearing for the main drive shaft is not positively located in the backplate 
and will drop on the floor if you're not aware in advance.
The reversing action in the latch section has a torsional spring that only 
marginally has an end retained and can jump this end lug.
If the auto reverse action fails to initiate and the internal little rotating 
semicircular pawl (fed from the train of 4 small cogs)jumps then the carrier 
for this is worn loose and needs a bit of packing glued in the space between 
the two parts. Failure to auto reverse at one end only - the mechanism initiates and 
the slide activates but fails to shift the spool drive from one spindle to the other.
 Probably due to worn cog axles,the teeth grab on in one direction and there is not 
enough force from the spring that connects with the slideway to shift into the 
opposite position. Remove this torsion spring and reform the tail arms so that the 
angled returns are nearer the spiral section to bring the two arms closer together.
Symptom :Tape playing warbled in one direction and ruffled tape but OK in other direction.
Which ever direction the tape was playing the trouble was at the beginning that is 
the tape winding onto the start of the spool of tape. It was not immediately 
obvious but the tinkerer had removed both felt slip clutches located on the 
spool spindles and were missing. Lack of back torque in the tape was the problem
To avoid disassembling whole mechanism made up 2 rubber washers with a felt pad between 
to stretch and slide over the tape drive dogs. Not matching spaces so different 
thicknesses of rubber for the supply and take-up sides and small enough to clear 
the spools of the cassette. One channel playing reverse of other side of tape 
due to misalignment of the linkage to the miniatute head select slide switch 
adjascent to the tape head.

Sony ICF C600 clock-tape-radio
Clock stopped with just colon displayed not flashing and 
no tape transport
Reduced the value of the 100K resistor down to 30K that 
feeds the mains freequency AC signal to the LM8364 main clock IC.
The cassette transistor switch activated by the leaf 
switch on the deck was malfunctionimg. Replaced this 
with a BD135

Sony HST D301 stack audio
Numerous faults.
Nearly all I/P and O/P sockets on the rear pannel 
had bad solder joints,not from abuse but poor production 
quality control,insufficient solder bath soldering.Squeal 
of one tape drive due to dirty pinch wheel and spindle .
Intermittent drop out of tape transport on other drive 
due to out of position tape-in leaf contact switch 
in upper part of cassette compartment.

Sony PS LX2, 1981 on diecast parts
direct drive
Arm skating across records.
With 3gm dialed up to take measurements with force gauge. 
Near pivot next to the Al block, 20gm and at 25mm from pivot , 8gm
with 1gm dialed up 16gm and 6gm as above positions
0gm dialed 14 and 4 gm
Skating due to bent stylus. Under a microscope x10 and thin nose pliers with some copper wire a tthe apex of the jaws to limit closure, 
either side of the stylus arm, bent back without crushing the thin tube 
carying the jewel tip.
Cleaned stylus with meths and soft brush
Moving magnet sony Cartridge XL-150, 
533 and 545 ohms
Undo mains Tx to inspect underside of motor pcb
M51725L SIL frequency control maybe equal to ECG1300 or CX065A
2x 4558D
7 presets , VR104 4.6K,2.27K,18.8K
.71K,.71K,22.4K+22.4K,22.2K+22.2K RV107


Sony PS T22 deck
lacking cartridge and offset mount.
Same as many Sony decks, how to make 
an adaptor to use a standard cartridge 
and a modified standard headshell.
44mm between stylus tip and the plastic face of the 4 way connector, 
120 degree offset angle.
Main problem is 5.9mm diameter connector rather 
than 7.8mm of standard headshell connector.
Found a pierced latticework type cable protector 
for a phone connector, was about correct diameter. 
Cut off a suitable length. 2 flat varelco connectors 
pins split to give 4 small flat gold plated conductors. 
Put a small bend on the end to hook onto the 
open end of the latticework. 2 small rings of 
sleeving pushed in , either end to keep in place 
while gluing up. Solder oned to the pickup end. 
Twist a ring of 0.3mm nichrome heater wire around 
and twist together, gring to length the twist to make 
the location pip for the connector. Repeat 
next to it to bulk up a bit, and glue together. Try in place 
for 4 way isolation and continuity to the phono 
leads. Cut a length of high temp hotmelt glue stick .
Hollow out with blades etc to make axial hole 
fo rthe wires  and 
stopped larger hole to take the latticework stub, glued in 
eventually. Managed to borrow an original to 
make a template by wrapping with ptfe and hotmelting 
the underside to get the right pitch, yaw and roll angles. 
In the end it did not match and had to adjust the headshell 
for levelness before finally gluing rod to headshell.
Cut off the connector end of a standard headshell and lightly 
melt the hollow rod to the headshell when located 
on the jig. Place the laticework bit in the arm, 
with back nut not fully home,
cover with a disc of PTFE , holed and split 
to go over it and hotmelt the 2 together. 
Increase the glue under the headshell and 
make electrical connections and cover the hot melt 
rod with silver paint to match.
Red channel is pair of contacts away from record centre, screen lowest
White channel is innermost pair, screen lowest.
Next time I'd turn and  drill out a piece of 6mm nylon and lathe-turn 
a groove around it to take the nichrome as the latticework 
was too soft to take the force of the tone-arm coupler.
Real pin is 1.2mm long centered 3mm back from the connector 
face and .75mm diameter. Perhaps I'd try a matrix board pin next time 
rather than wire and part of a preset extender rod/knob instead 
of the latticework, insulating around the matrix board pin 
so the split gold plated pins can pass around ok.


SOSL N-X-211,Retro 1940s CD player , no CD
Weird one built into a (plastic) simulated Al flight case  with hundreds of real screws for effect.
Cross-head not slot-head though, 40s/50s assemblers and repairmen 
had no power drivers and could handle screw-drivers without slipping.
2 simulated analogue meters, black front panel, black and Al  plates and white & red chequer plates, 
proper traditional toggle switches instead of click-switches ( the only decent bit ) etc.
Opening the case there is even an odd musty sort of smell, probably 
the gummy glue used all over the place.
To open case remove 6 long screws at rear, 2 feet and the side hinges 
to release the grommet material and prize apart 
the grey & black sections which are gummed together.
Anyway probably made 1993 in China. Bass boost off and side speakers disconnected then 
no output, bass goes through body speakers, also no balance ,treble 
or bass controls.
Fault
Radio works but no power at all to the CD area. The CD status lamp (simulated pannel lamp indicator) 
does not light either . 2SB777 gating transistor not passing 15-16V to CD section.
4013 pin 12 o/p ok on CD select also i/p line to 4052.
The 3.9R presumably fuseable resistor is o/c replaced with 
0.5A fuse in series with 3.9R, 0.5W metal oxide.

Steepletone Edinburgh retro music centre, post 2010
Even the model name reflects the era of these being pieces of furniture.
Quite a tasteful bit of cabinet with convincing looking faux bronze
"metalwork". Inside basically repackaged ghetto-blaster, 350 GBP for these .
The main analogue board would normally be a reject at pcb etching stage as
about 20 breaks in tracks due to excess etching . Factory re-work
hand-bridged with wires soldered over the breaks. Probably failure of one of
those fudges at a pass transistor pad ,meant loss of all audio out, not hifi
in any way though
Back working again. You'd think for 350 squid that they would have used the
Tone and Balance controls , not just a few presets,built into the stereo 4 ch select and vol via I2C
IC, PT2314E
First time I've come across the name. The pass transistor and its large but
un-anchored heatsink would likely flop about anyway in transport , without
any duff pcb track rework
Other point to note, the main digital control board is housed in a tinplate
screening-can and just stuck with gummed tape to the recording-CD casing
Once I'd worked out what each board was doing , I found it quite
straightforward to work on.
Removing the rear and top vinyl deck and then to avoid disconnecting the
rat's nest all those wires, pair of Mole grips to break the glue join and
bend on the nails of one of the wooden "card rails" to release the main
analogue board.
As far is known , only used in living rooms, no storage in garage or shed
but the inside of the cabinet has a grey-green mold coating seemingly in the
area where glue is used. Perhaps they used traditional cabinet-makers
rendered down horse glue.
The other reason for breaking the "card rail" was not to have to break the
probably 3 sticks-worth of hotmelt glue , all over the place holding down
things that would otherwise float around, so plenty of flammables around
Remove back panel , remove top wood . Remove the captive "circlip " 
from the transport screw of the vinyl deck , rear one only. Then deck lifts out , sliding out the 
other transport lock-down. 
Mains fuses and others inside are ok.
Silvery mesh braid is screening cove rto the riubbons and also used for fixing the control board 
box to the recording CD case.
5K3 across mains leads must be the small Tx only , for standby function.
No speaker hiss 
Fuses ok and have 15.6/15.6/4.6V ac on them
8sc around the inside of the front panel, mark and disconnect cables
Black screened wire is radio only.
Vol control digitally via I2Cand IC3 PTC PT2314E  the screened boxed digital control board stuck with tape to the 
recording CD case
on main analogue board failed wired trace rework to Q7 and R62 , 1R to main + power rail.
Q7 wobbling with its h/s. Mole grips squashed inwards the tangs of the h/s to grip 
the pcb and redid soldering
tin plated vaned IC4 is the audio o/p IC
Vinyl deck band .5x5x530mm , 11% extension with 400gm appplied
IC8 7812A, 7812A,  B1566E, S7805, TC1117, 7812A along main h/s
8 pin IC LM833N ?
Q21 B772
IC201 7808A
errant pass Q, not noted
3 wire board screwed to the side panel -50mV, 18V,5V
If the recording CD is disconnected on power up , then no function of the whole unit
Also for audio out , the lead to the phones so. and so bypass sw contacts need to be connected

SteepleTone Edinburgh
left , play only , deck would only open sometimes
to power this deck requires selection from display
4sc on outside are faux.
Remove rear hardboard. 4sc under , melt hotmelt over wire 
and connectors to control board.
Easy to replace drive band for drawer , not perished. 
Probably stick/slip of plastic drawer against side guides.
To convince not due to gearing backlash, remove drawer by 1 sc one side and springy post on the other.
Remove the one accesible sc with washer and spring to the slide mech. 
Slide away and strain a bit to remove final cog of the drive train. 
Then reinsert drawer and try moving without gearing. Free moving at end 
of travel but not centre. Presumably the plastic had warped and combined 
with heat and off-axis movement, would jam enough to stop the gearing. 
Shaved back the 2 guide posts on the easy to attack side, razor on smaller 
and dremmel disc on larger, then silicone grease.
3V, .1 amp drawer on bench ps and .5 amp stall at ends
Refitting deck to box, card around the edge to align
2 thick  sc are for phono conns at rear
Deck number ? BB0625
LA9242,LA654,LC78602R
similar cct perhaps to Grundig RRCD4101

TCDR 993C E921
Chinese no name music centre like Steepletone concept above.
Owner tried changing the stylus and broke the headshell coupler. 
It looks like proper conventional 4 contact and back-nut holder but not.
4 wires pass through the holder to the headshell, so cannot 
totally remove headshell. The pin across the cylinder that engages in the 
cam track of the back nut fell out. 
Squash the double pin con of the 2 grounds to pass back 
through the cylinder. Drill a part hole on the opposite 
side of the hole in the cylinder and epoxy there and the hole , to 
refit the pin.
0.85 diam x 8.3mm pin
smallest cylinder type cintride bit , grind slot opposite hole   in 
preference to drilling as likely to make oversize, epoxy in place
notone control found physical or virtual
piezo pickup, bent radially the pick up arm
cut back part of cartridge and the shoe of the stylus to mate up 
but stylus angle near horizontal.
Cut U shape central section from a crimp connector pin , slid 
over the stem, set in the rubber yoke, with a dot of clear 
nail varnish

Teac AG 260 Tuner-amp
Crackley volume and loss of bass.
Uses a bass compensated volume pot - worn track 
- recondition as per tips files.
Remove front panel PCB and use hot air 
gun to de-solder and prize-off the pot.

Technics SA K2 tape,tuner,amp
Intermittant loss of Output especially on power-on
Corroded contacts on the phones outlet socket 
on front panel that switch in or out the speaker outputs.
By pass the switch contacts by adding a toggle switch .

Technics SA Z5L tuner amp 1995?
No am or fm but aux to op ok.
TO220 ps pass trannie temp affected solder.
Bolted a finned heatsink using the existing 
heatsink bolted through trannie hole.

Technics SL1210 , 1979 ?
Intermittant loss of one channel.
The headshell was slightly loose on the tonearm 
and moving inwards would cause loss of one channel.
To remove this arm undo the slotted lock ring at the very top 
of the arm pivot and undo the central pin. The arm 
with jiggling can then be removed assuming enough slack in 
the signal wires. Undoing the 2 watchmakers screws near 
the headshell allows removal of the 4 pin connector.
Presumably the wires inside the tone arm at this connector 
could touch the inside of the tonearm and lead to 
break in sprung connection. Placed a bit  of brass shim 
in the slack area and pushed back in to wedge tight.
Also removed the soft washer on the plug shaft of the headshell.

Technics SL 1210 Mk2 ,1979 (electronically much the same as SL 1200 )
Wrong dedented speed,no stylus light and sticky / rubbing ? tonearm .
On test point 27 the f on a counter should be 262.08 KHz (for 33 1/3 rpm ,/N=162 
;for 45 /N = 120 ) so 262080 = 162 X 33 1/3 X 182 (pips on platten) X16 /60 seconds. 
Was about 261.60 KHz. Green LED on dedent lights on speed lock and strobe 
freezes large pips on platten periphery.
Stylus lamp was blown 20V small filament lamp ,filament not ideal because 
of percusive nature of the pop-up action plus unavailable 20V. 
Placed a slab of rubber loosely around the microswitch latch assembly 
to cushion this judder when the lamp assembly hits top.
Replaced with 3 slab type LEDs 
soldered in  parallel and ground down edges and front faces to feed into the 
Ali slot. Bed in with mastic or "blue tack" to position and glue in with hot-melt.
Run from the supply with a 200 ohm,2W R in series.
A better solution would have been a high intensity 'key fob' blue 3mm LED 
and 470 ohm bent , wired and insulated as a replacement, I've since used 
on other 1200/1210 decks.
Checked pivot adjusters, lock nuts had "loctite", so heated with soldering 
iron to free up. Problem was probably crossed turns of the hair spring torsional 
spring for the anti-skate mechanism. To remove tonearm (first remove 
headshell and cartridge) and set anti-skate 
to zero. Undo signal lead clamp and all screws from the underside of the 
mount (including under the terminal board) except one nearest the vertical 
pin that is touched by the anti 
skate spring. Tie cotton to the fine signal leads before extracting.

Technics SL 1210 this time with guillotined lead to the stylus illuminator ,
no green LED on dedent position of pitch slider pot
The silly ring of soft plastic around the brass barrel had broken 
allowing the slide to go far enough to cut the wire to the lamp. 
Also missing tonearm lifter lever. Found a length of brass hex 
spacer threaded 3mm one end and tapped 3 mm at the other. 
Broke up an old standard size paddle toggle switch for the 
plastic paddle. Heating with low setting hot air gun melted 
an angle into the pivot area and tapped a 3mm thread onto 
the switch end of the paddle. Screwed into spacer and 
screwed other end of spacer into the horizontal rod of the tonearm 
lifting mechenism. LED problem due to o/c switch in detent f lock 
position. Nothing done to rectify as owner content with knowledge 
only cosmetic,this switch is built into the slider pot housing.

Technics SL1210
Broken power switch.
They tried being clever but too complicated. The shaft of this mechanism passes 
through the LED strobe housing. The brass shaft is not mechanically held 
to the knob positively so breaks away and shaft drops internally. Replaced 
the 'cam' bit that activates the microswitch with a brass cored plastic knob. 
About 12 / 13 mm diameter ,replaced the grub screw with a bolt . Due to 
it being a standard 1/4 inch knob and the brass shaft being only 4 mm or so 
when fixed against the flat the knob is off-centre so acting as a cam.
The flutes on the edge of the knob were useful for feel as well.
Added a bracket piece to form end stop for rotation 
by hitting the extended bolt in the knob.

Technics SL1210 Mk 2 , 1983
Non-technical owner had service manual and tinkered inside and 
managed to blow up the power supply. Main pass Tr ok but 
had to replace the 2 2SD637 with 2N3904 with swapped legs. 
Also the 5.1V zener had gone ohmic and replaced 400mW with 1.2W.
Main crystal osc. locked on f, all 3 drives to platter are working
and once settled at 33 or 45 RPM it all stays locked into speed strobe.
Always from start or from 33 to 45 locks in quickly but sometimes , about
1 in 3 times going from 45 to 33 will take 2 to 4 seconds to lock in to
lower speed.
Rarely will the brake properly fuction ie stop
between 120 and 270 degrees after stop signal at zero degrees, usually
continues jerkily faster than 45 rpm until the power cut ,time-out, after a few seconds.
Makes no difference to the jerking what setting of the brake adjustment pot.
Adding the heavy rubber platter mat does not damp things and improve matters
thinking some servo gain/resonance effect. To monitor voltages 
needs small hook probes and wires fed through the illuminator 
access point or bottom and top halves of unit unfixed.
Seemed a problem with the section of the AN6680 custom IC that outputs the braking
signal to the drive IC. The main f oscillator section is fine.
This errant section gates the 33/45 switch and start/stop switch.
Should output 1.5V in run and 0V on braking but in the non-locking
45 to 33 changeover and lack of braking situation it is outputting 3 to 4
volts.
Added a 1.5V zener and a 2.4K limiter across the capacitor connected to 
AN6680 (21) / AN6675 ( 22) trace.
An ongoing problem, not explored as minor, is unit needs switching 
on 3 minutes before rotational use. In those 3 minutes perfectly useable 
but only 99 or so percent lock to speed.
In passing, placing a 1K across C214 100uF cap so simulating a leaky 
cap produced highly errartic forward and backward rotation. Whether 
would happen in general case or just because of the fault in AN6680 , i don't know.
Pitfalls 1/ the index 'pip' for positioning the bearing into the base is 
not at 12 o'clock but 4 o'clock position.
2/ convenient earthpoint is ps pass transistor clip but that needs 
earth continuity via one of the PCB mounting screws in place.
3/ With upper cover, under platter, removed to work on it, 
is possible with fingers in the platter to place/remove, it 
is possible to touch live mains components.

Technics SL QL1 radial linear tracking vinyl deck, 1981?
Perished "rubber" platter mat, presumably thinner than original but 
as hard and brittle as shellac or thin bakelite in appearance 
and a pool of a light oil under the mat. Had also 
perished trhe rubber in the traverse section in the hinged upper section.
The 3 small radial slots either side of the mat line up with the
3 LEDs under the platter and 3 receivers above the record/platter and 
also holes in the platter so matter of
cutting holes and adding rear locators to the mat for alignment. 
Marked positioms , sewed some loose thread into the rubber 
and filled with hot melt glue , then repositioned, marked 
for the 6 small holes and cut with leather punch.
Don't unscrew the hinges , just the top under-cover. 
The size selector is not a switch it just obscures 
the LED receivers in turn.
There are 2
VR accessible via a rear plate but presumably 33 and 45 rpm adjust.
So just masking off them and taping down the cover closure microswitch allows
exposed to work on in operation. If rotation hares away then platter has slipped 
from near hall effect sensors.
2SC1846 5,12,5.7V
2SC1846 12.5,22,12V
in operation ( 2 tight grommets over spindle to allow use upside down)
CN304 9.4,.15,0,0,6,3.6,0,5
305: 5,0,0,3.5,3.1,0
302: 11.7,5,0,8.3,12V
305: 1,0
301: 0,3,0,0,0,0,5,1,12,0,0,0,

Technics ST-600L
Intermittent loss of display.
Replaced the on/off switch but on replacing 
noticed the problem may have been due to a 
broken pcb track as switch not mounted to chassis 
but straight to pcb so strained if heavy handed.
For the extended stand-off removed one switch 
from a ganged array and wired the latch to the 
body of the switch

Toshiba SR-B30F deck
Twisted and bent 63M cartridege stylus shaft..
Pulled out with no more than fingertip pressure 
and again with fingers only as a hollow aluminium 
shaft, bent back straight. A spot of glue in the 
housing and replaced

Trio / Kenwood KB 1022 record deck
Platten rubbing on chassis. Also the new owner did not realise the speed 
change lever should be returned to neutral midway position in play.
Undid main spindle nut to remove spindle. Removed small screw to 
disassemble and cleaned out with meths. Dropped a small 
washer into the housing then the ball bearing. This raised enough to let 
platten clear the deck.

Trio / Kenwood KR 2010 Tuner-amp
On one channel sound ok on phones but distortion on 
full load with speaker.
One of the pre-driver trannies was partially O/C all 
4 power trannies ok

Wharfedale NE571 MP3, 2007
The LCD display through the mirror finish 
seems to be lacking contrast , as "designed" gimmickry
Broken top cover, at the hinge, can be still used if remnant left 
hand hinge in the right place. After taking apart 
glued left hand part with hot-melt string "soldering" 
and prepared both parts of the RH side before assembling 
and then adjusted the top closed limit switch.
To open case remove arrowed screws plus 2 unmarked 
at the speaker cons and knot in aerial wire.
uses BA517, 2x A9208A
intermittant one of the blue LEDs on front.
Prize off the cover strips above 
and below the volume knob , then knob 
and light guides remove to resolder LEDs.
No tape function , graunched tapes due to 
broken 1mm AF second drive belt.
14V ac on yellow and 12V on black
Mark all ribbon connectors before 
removing and wrap reinforcing tape around 
the 2 foil ones before re-fitting.
FF and REW buttons are reverse order confusingly.
To remove cassette cover lift upwards 
when open , then force the rack parts over 
the pin. To reconnect the spring hook 
it into place after refitting the flap. 
To refit the top button cover spring.
Align joggled end in the slot 
in the static black mount and other joggle end 
in the moving hinge so the joggled end 
moves in arc in the recessed part at the U bend.
On reassembly make sure the main pcb slides 
into a guide slot to get the speaker cons aligned with the casing.

 Cassette and Tape players 

Sticky dampers on cassette flaps
The compact dampers based in a cog that supplies friction against 
the spring action.The construction of these is 5 or so concentric 
rings engaging with a matched set and friction supplied by silicon 
grease which can go viscous with age so wash some of the grease out 
with methylated spirits

Aiwa AD1800 1972 tape deck
Broken main drive band preceeded by intermittant aborted play/record.
Remove top cover by sliding to the left and unclip. Remove 6 screws from the 
base . To remove front panel remove 6 more screws 3 machine and 3 tapered.
The main drive band has to be wide enough as well as right diameter or it 
will ride on the balluster pulley .
The "running" light would stop soon followed by drive stop. This is fed from the 
hall switch near the tape counter which had moved away from the magnets so 
moved back and anchored. Also slipping drive bands replaced between 
take up spool and counter.
Second machine same model. All belts perished,no transport. To remove the cassette carrier 
remove 1 circlip and extract the black pivot rod. To get to final counter drive 
band remove the 3 screws that bolt this sub-assembly to the chasis. Remaining 
belt exposed by removing flywheel remove circlip to pivotted arm . Replaced 
pulley tyre and the associated band. Bulbs probably 6V driven by 5.3V ac.

Aiwa AD 6500, 1975
Main deck motor 12V but about 10.5V dc from the supply, nothing wrong with
the ps and nothing wrong with the motor and its regulator. All that is left
is the mains transformer.
I happened to have a near exact salvaged motor to swap over , pinion is grub
screw fixed, so easy. Maybe both hare wrong the same way. Much the same
result of DC <12V and too slow deck drive. It maybe that the drivebelt is
super critical but the dc over the motor is only about 12V with another
belt, so loose, that the pinion slips under it.
Transformer seems fine, no buzz or heat.
An attitude problem. Bench tested/loaded both motors laying horizontal but
the Aiwa one does not like being upside down, as in actual useage, doh.
Much the same, half wave, switches, cap that I repalced was 1000uF, 25V now
2000 uF. Switch contacts were the first thing I checked. No its a motor
problem and very critical on drive band properties, the main one and the
FF/REW one they both interact of course and only a narrow range of tensions
allowable. 11V in play and FF/REW now and speed constant and upto speed. I
had to convince myself it was a motor problem by connecting in 6volt ac at
the motor fuse and it made no difference because of the NEC upc1003 inside
the motor limiting current. I doubt these sorts of motors are available new
these days.
I checked rec and nothing except erase.
Does the 6300 use 2 separate single in line rec/play changeover switch
assemblies. The 6500 ones seem to be 10 pole change over , straight from pim
1 to 30 except 3 in the middle which don't switch over to anytrhing else ,
both L and R switches failed? the same which seems very odd for each to
separately loose the same set of contacts .
Alps 10 pole c/o R/P switch type 82-371-620-01, quite easy to 
desolder. Remove the spring , inserting a sickle probe to 
retain the spring. Problem of distorted sliding phosphor-bronze 
contacts failing to contact on the fifth contact back from the 
transformer causing loss of record signal, 
just erase only.
Had to make a wide , low tension drive belt , see tips files
Used a double, ie uncut centrally by 2mm spaghetti cutter , 
4mm band and 350 mm in length, 5mm wide would be better.

Aiwa AD 6900, 1978 tape deck
Cassette play drops out after a couple of seconds.
Not made for maintainence or repair.
To get to mechanical deck requires 
removing front panel and 3 headers to remove 
through sub chassis. Then sub chassis 
requires 2 screws removed either end of monitor & tape select switches. 
3 screws mounting large solenoid to base.
Unclip shaft and remove mains switch.
Remove left-most vertical pcb. Remove tape 
counter band .
The 3 meter function select sw extenders are very 
weak at junction of clear and chromed plastic. 
Remove the cassette deck back plate and 
surround plastic trim. 2 screws were too tight to 
unscrew and needed grinding off.
Remove sub chassis , numerous peripheral screws.
To replace spool drive band remove the 3 screws 
holding the white pulley and slip clutch 
assembly and joggle band around the end of shaft.
Drive problem had probably 2 causes.
The take up spool brake rubber had part broken 
or deflected allowing the arm to rise too high 
and fouled the jockey assembly so high speed 
spool drive part engaged in play. In play the 
sliding jockey was marginally touching a 2mm 
drive shaft. This was probably covered in a 
plastic cylinder extension from the main FF section 
pulley. Interference fitted a 4mm brass cylinder over 
this 2mm shaft. Also made a bracket to hold 
back the top position of the spool brake. The 
supply side felt brake also needed attention as 
thin and polished. The sliding jockey assembly must 
not have too strong a spring to engage as then 
the whole play sledge plate will not reliably disengage. 
Finally a clicking noise from the take-up spool. 
The spring immediately under the cassette engaging 
drive dog was compressed to solid and the plastic 
piece needed pushing back to compress the conical 
spring to bring the counter band into alignment.
AC voltages at fuses in play mode
11.5,25,16.5,16.5,8,16
Voltage to deck illuminator bulb is 7.5V ac

Aiwa AD 6900 Mk2, 1979 much as "mark 1" but added sensor and board
Similar lack of drive due to perished rubber parts.
These things are designed to try the patience of a saint. 
Everything requires something else removing before you can get to it 
and nothing is self-aligned before screwing back together again so 
before undoing a motor or tape deck or whatever mark around it 
with felt tip pen, especially the solenoid mounting plate 
and the isolated screw through an cartouche-shaped slot underneath. 
Reassemble this last so that the obvious play/disengage 
slide works but also the hidden secondary linkage that 
operates in reverse sense to disengage brakes and lock the 
FF/REW pulley in central position play. Jiggle around 
this mounting plate , slightly lifting and dropping into 
the hidden locating slot. If in wrong position, the hidden 
slide mechanism fails to operate and you can get fast and play 
modes operating at same time and tape pulled through capstan gate.
Disassembly as other 6900 above, keep sub-section screws in labelled bags.
Deliberately made awkward, the slip clutch spindle bearing 
mount could have been rotated 60 degrees so not difficult 
to undo the bottom screw. A slot could have been put in 
the front sub chassis plate so the wiring to the 1/4 inch 
sockets could pass through to give more space to release 
the deck section. I still don't know how one is supposed 
to remove any of the 3 off 1/4 inch front sockets for replacement.
Each seems to be pushed through a hole (not two-partable 
sections ) and then held in place by pushing a rigid plastic 
ring over the barrel and locking under the frontmost lip. As this plastic 
pokes through to the front I don't know how you're supposed 
to remove it un-butchered - hot air gun softening ?. 
Otherwise requires a source of large LED mount 
back ring/locks to replace butchered originals. ? Cut 
down BNC socket cable entry protectors cut down and 
then body of socket glue in would probably work.To remove 
the play mode slip clutch spindle as above. To totally 
remove , first remove the take up spool then remove 
the slip clutch pulley from the pivoted arm. Pull out and down this 
rear clutch section to give space to remove the other clutch 
assemply. Replaced that 0.65 inch tyre with an O ring and smaller packing O ring 
giving 0.67 inch.
Don't know what the tyre diameter on the front removable 
sliding arm is but this had perished to a rough 0.71 inch,0.76 inches is too 
small ,  
replaced with a "O" ring that gave an outside diameter 
of 0.75 inches. To do this with a standard 0.675 inch by 0.1 
inch, wound ten turns of 2 thou plummer's PTFE around the 
pulley before fitting the O ring, remove the 
excess PTFE to avoid snagging. I know not of a source of small diameter 
but radially wide pulley tyres so interference fitted a 
piece of brass 0.3 long and 0.135 inch diameter on the play 
drive shaft that engages with the sliding pulley. Replaced 
all other drive belts. Main capstan belt requires removing 
the back plate to the spindle.
That damn solenoid linkage fouls onto everything unless you 
reposition it and the solenoid last, despite having to do it 
totally blind. Even replacing the main capstan belt would be easier 
if those 3 flimsey switch extenders were easily removable whithout 
the glued in lock plates. Used a dentist's sickle probe to excavate the 
glue and then prize them off. Don't remove the screw accessible inside 
and thread pokes through base plate that holds 
down the capstan motor unless you really have to.
To replace the back retainer to the capstan spindle hold the "nuts" with 
the sickle probe, rotating with a small screwdriver.
Remove the counter mechanism to check the drive band 
is in correct position as cannot see otherwise.
Replace the four switch extenders last and also the plastic 
fairing around the cassette flap goes in after putting 
the front cover on.
Tape remaining lamp supply measured at 7.5V, replaced 
with 8V, 0.06A bulb

Aiwa AD 6900 Mk2, 1979
R/C tr uses 4028 and M58484,and rx LF357 4558 555 
This deck stopped responding to the r/c.
Transmitter was ok , receiver diode ok but nothing coming out of the first
op amp. The o/p is dc coupled to the next stage. The DC at the op-amps was 8V.
Replaced the LF357 and m/c works all functions but only in subdued lighting.
If room light is too bright then there is not even manual control of the
deck functions let alone the r/c, kill  the room lighting and normal service
is resumed.
Fluorescent light was the problem , exploring further.
No room light CFL and shining bright torch at the sensor does not affect the
function control but rapidly moving the torch back and forth can set it off.
In that state a continuous 1KHz pulse train positive 
going on orange and -ve going on green until switching off and on.
Seems as it was an early IR r/c it just lacks discrimination .
Replacing Cs 4558 and 555 made no difference.
Its not used with a flourescent roomlight but if it was then a matt black
rubber cone over the sensor boss would allow it to be used.
Returned 5 years later
Tip contact only on phones and one phono o/p only, both signals on meter
L only on phono out
Fiddling with Monitor sw while playing made no difference, slight click on 
R of phones but no signal. Click of relay on changing sw posistion.
Ground back the Y and Gn wires between op level pots and monitor sw, signal 
on both
p3 and p8 of IC1 ok but no signals on IC2
Other pair of y & Gn to main board at points 26 (no signal) and 27 ok
So problem at the pots
Unplug sensor cable and feed forwards the other cable mass to release the front panel. 
Undo chassis sc at the pot corner and under front edge leaving jus tthe farthest one and also 
the sc at the EQ pot, gives enough movement to wangle sliders and its pcb 
through the hole i nthe sub-chassis. The large pots are locked into that corner by the 
vertical pcb. 
Broken plastic nib on the slider block so loose contact wiper. 
One pot measured 6.3K to 0R and the other 112K at any posistion.
Robbed a slider from another 
stereo pot of similar design. But slightly deeper so a loop of lacing 
cord at each end to pack out between the tracks board and the casing.
2 smallest gauge sc fix the slider pot to the chassis
This broke up with the long stem business, so found a long stem pot , unfortunately stereo 
linear and 100K but all that could be found with long stem. Ditched the silly slide support 
and joggle fudge, and ground the stem tip to take the 2 part plastic knob
NB mark the 3 small central preset shafts posistions , as found , before removing the paired-up knobs 
from the front

Aiwa AD 6900
weak FF , no play and clanking noise of 
broken/perished sticky flapping drive band hitting a spring.
much as before tips.
top idler drive spindle , black plastic 4mm diameter.
Obvious, immediately under back plate, idler slide mount spring 
coil section expands to 10mm on 50g force.
Hidden idler , beware removing copper disc as 
spring under, diameter 16.7mm of tyre
capstan band 220mm
counter belt 150mm
removed and inverted the 2 pulley tyres.
At least I'm not alone, in touching these and in thinking they are right
pigs.
To get to anything, you have to disassemble something else and some you have
to jiggle around blind, before they line up again.
Got the manuals this time, for 2 to do, and the first I went through
dissassembly as per manual, which involves demounting the mains transformer
and like everything else the loom lengths are not enough to stow this big
lump out the way. Then a horrendous rat's nest of wiring to negotiate, and
managed to strain the deck light wires and of course broke at the bulb.
I think the second one I will do as I've done before, to get to the deck.
Remove the front and sub-front to free it. You have to wrap up the meters to
protect them and you cannot totally free the panel because the 1/4 inch
sockets are one-time fitted, and other end of cables inaccessible, so the
whole subpanel dangles, but easier to tie it up, out the way. That is
preferable to a dangling transformer and the rat's nest.
If warbley slow sound, check the vertical solenoid is activating 
to pull off the brakes.

Aiwa AD 6900
no capstan belt drive, loose headphone socket barrel, no 
top black pinion that engages the take-up spool in Play mode
This time ( 2 of 2 to repair) reverted to removing the sub-front panel to get to deck.
Release LH side pcb and mount to give slack 
to the sub-front and 1/4 inch socket bank cables 
and for sighting solenoid screws on refitting.
Cut wires to counter and join on reassembly
Pull the slide switches through sub-front.
remove power sw
2 screws either end of long cover over the main pcb to 
leave it in place.
Remove all around the vol control
2 pot back nuts 
undo the 2 nuts holding the meters in place 
and tie back to body of m/c
remove the 2 underside recessed screws but leave the 
2 recessed in slots to keep deck and motor in place.
small vertical solenoid disengages the brakes.
replace 2 front switches with yellow and brown wires visible through 
slot. Counter slots in downward 
before fixing, counter belt 170 mm.
large horizontal solenoid pushes the deck up and the 
clear plastic linkage pulls the hidden tyred pulley 
away from take-up spool, otherwise used in FF & REW. A capacitor , which unknown, 
in area of large solenoid retains a charge after switch 
off - heard a spark when moving metalwork around.
Anyone been inside the sockets?
http://www.diversed.fsnet.co.uk/aiwa_sockets.jpg
The barrel on the second from left loose. Cut away the black plastic and
shows a deep recessed ring on the barrel that the plastic ring must force
into and hold the barrel in place.
Via the gap in the mounting plate it is possible to see inside and the
silvery protruding barrel is swaged out , rivet fashion , under the backing
plate and earth tag, so must be assembled/swaged from inside the socket
before the contacts are placed inside . Innards not removed as requires
desoldering a number of wires , cleaning off all solder and pulling the
pierced rear paxolin sheet. Anyone know how the contacts are fitted inside,
for any future revisit to these awkward sockets.
Patching up again, matter of twisting wire into this recess to tension up, a
ring cut from a piece of power cord gland rubber stretched to fit
 over , bodge covered by the front panel that goes over these 4 sockets.
Replaced bulb on deck with 10volt one.
Brake problem, holding on firm during play so warbled sound 
and failing to engage on braking from FF or REW.
3 glued in screws holding the motor holding back plate on.
Come to replace them and they are not in fact 3mm , bit larger than 2.5mm ,
they would seem to be 3 UNF threads on 1978 Japanese Aiwa AD9700. Well 3 UNF
threaded screws have gone back in there comfortably and securely, manual
just specifies some company stock number. Whatever they were , for the size
of crosshead (saves argument),  they were well glued in .
Had to revert to my previous technique of grinding 2 flats into the domed
heads and then 2 could be undone with a small 3.5mm open ender screwdriver.
This time used an 1/8 inch cylinder cintride burr in a Dremmel instead of
small grind stone. The other 2 I could get to with a pipe wrench, of all
things, because of the good leverage and right angle action.
So perhaps a sight no one has seen since production of Aiwa 6900 tape decks
in 1978. Trying to sort out a brakes problem otherwise totally enclosed and
impossible to glimpse any sort of view, only rather confusing exploded views
in the manual. B = brakes, S = their activation solenoid, Su where supply 
spool goes, T position of take-up, I iron pillars the 
seized screws mount in,P one of the 3 pcb lifted, 
D deck lifting linkages , C capstan bearing,M deck functions moptor
(wrong model number crept into the pic names, 6900 not 6500)
http://www.diversed.fsnet.co.uk/aiwa_AD6500_deck_a.jpg
the hidden jockey assembly and its activation lever train
http://www.diversed.fsnet.co.uk/aiwa_AD6500_deck_b.jpg
with secondary motor under the rubber pulley and mounting plate
So it is possible to work on the deck without half taking the m/c to bits
first, just 3 pcbs unscrewed. So you have to reassemble before checking it out and so often you put
something back in the wrong position. But you do have to wrestle with those
glued screws. As one of them has nearly straight action with long handle
screwdriver but would not undo, then still a problem with the deck removed
and a straight attack to all 4 screws to get apart.
If the deck motor operates erratically when it should be 
stopped check you've added the mica under the TO126 motor driver 
transistor. Removing capsttan flywheel retaining bar only 
slacken off the inner hex "nut" and slide off to assist reassembly
Runner brakes replaced with 15x4x3 mm lorry tyre inner tube 
split with 1mm drill bit at ends and cut with fret saw inbetween . 
As no horns on the metal , held down with a pair of 
small rubber drive bands. Added some sleeving to the 
rear extender that engages with the solenoid lever.
With the power off the take up brake should operate when 
rotated clockwise and supply side anticlockwise.
Small solenoid operates in TT and REW to disengage brakes.
Deck functions motor is 1.9mm diameter, 
found a brass cylinder 4mm diam, tapped , so drilled out 
with a 2mm drill (actually measured 1.9mm ) , 6mm long, 
pushed over the spindle.
Then drop of superglue on the top to capillary take in.
Card introduced between the left pcb and chassis as little clearance.
FF/REW motor band 90mm, release the 3 rear bearing mount screws 
enough to let the top spindle fall away from slot to allow 
the band to loop around the assembly.
Bad record volume control on one channel, corroded/worn 
pot. Beware on opening the one or two coppery leaf 
springs just laid into a recess on the shaft, open constrained in 
a box to catch them.
Final order of assembly is front fascia on then 3 sided 
black plastic blinder, then deck back cover.
1 amp fuse in fuse array failed. 1 amp of current 
in use , peaking to 1.3 amp at motor start, eventually 
gave out , replaced with 1.25 amp (T)
40gm for 100 percent elongation spring for the 
diagonal sliding pulley carrier arm.
Aiwa AD F410, 1993
Warbling tape play.
Seemed like a good design for changing belts etc.
4 screws to remove the deck from front.
Pinch wheel unclips and 2 screws removed allows 
to remove back plate and main belt slips 
through gap under the pcb.
Not a belt problem, speed warbling, 
too much take up (TU) tension. With hindsight the 
TU spool will disassemble with finger pressure but it seemed one piece 
construction with the counter pulley, pack out with large nut , say, 
around shaft and use  a blade to prize off. Access to slip 
clutch otherwise is through the deck side , not motor side.
Mark sections before dissembly.
Remove thin stainless steel plate between the "2" pinch 
wheel holes. TU side unclipped then S (supply ) side ,reverse on 
assembly. Beware of small BB under this plate.
By joggling the 2 sliding plates will come away.
Small spring to top and larger spring to lower plate.
The 2 white trigger arms , the one that folds back around 
the pin is the TU one. For reassembly 
tie both these arms down in place with PTFE tape stretched 
right around the deck , remove after putting plates back.
Same with holding BB in place until cover is back.
Replaced the existing slip clutch spring for a lighter one.
TU drive in play needs the pinch wheel assembly in 
place. S side solenoid activates play drive and 
TU side one for FF,REW.
Then too much braking on the S spool when a lot of 
tape on the spool so changed that spring as well.
The spring end extension under the pinch wheel 
was bent so too little pinch pressure as well.
Beware there is no screened cable from the tape heads 
and don't power up with the ground wire disconnected.
If no earth then a curious distortion takes 
place, semi-random bursts of fast decay high-f oscillation 
 pings or tings overlaid on tape signal.

Aiwa AD F450
Dropped or forced front flap after tape jam , rather 
than removing cover and pinky under the deck to turn the 
capstan.
Dislodged small torsion spring under the pinchwheel , near its large 
torsion spring. Thin tinplate closure plate , that holds the 
main deck slideway in position had dislodged due to one of the 
slotted anchors having broken off. And on top of 
that a slack main drive belt. The counter belt 
is just for counter , autostop is in the deck mechanism.
Turning mechanism by hand, or powered without tape flip top lever, 
pull the solenoid up to engage play modes.
Glued a piece of small nylon cable tie to the available deck points 
and cut away part of the front cassette space moulding that fouls on this 
thicker material than the tin plate.
First use of Silicone Muffin Mould drive band. 
Could not measure length of band as a third pulley 
and construction. The original , too slack , band 
measured 218mm inside circ unstretched x 5 x 0.55mm and 58 percent / 500gm (single ) 
elongation. Silicone material stiffer than the neoprene 
so made a band much the same circ as the original as was certainly 
not loose around the pulleys, just not enough tension within.
Blue Silicone band , 216mm x 5 x 1.4mm , elongation 36 percent / 500gm 
and 1mm holes punched every 10mm on tight side. Did not try splitting 
of a shorter band as the thicker band did not foul om any fixed part. 
Did not take up a lay central on the third pulley, that drives the mechanical functions
 when engaged, but itself is always spinning. 
This was a flat plastic cylinder 
of width about 8 or 10mm then rims but band moved to the slacker, non holed side, 
touching the rim. 
Added pairs of 1mm holes between the 10mm ones, nearer , even partly on the centre 
line , took up a better posistion on the drive pinion 
but still to one side , the fair original silicone mould edge, 
on the third pulley

Aiwa AD F770 , 1985
Semi professional deck that uses "3 heads" so record monitoring 
is via separate play back heads, not off the direct signal feed.
So VU / PPM only indicates in record after 
the tape has gone from leader to ferrite.
Uses a second tape guide in association with the "reverse" 
downstream pinch wheel and spindle for better alignment 
and also paired up pinchwheels (not for any reverse/ loop play 
function). Apparently improves registration over 
the head and so more reliable high spec performance.
 double tape guide 

Perished belts and prior to that erratic FF and REW and poor eject.
As received the cassette would not eject as in tape 
play position when band broke. Engage the centremost 
solenoid while turning flywheels to disengage the slide.
To remove the deck , remove mains switch bracket, cover the pcb directly behingd the deck with 
plastic to avoid deck catching on it. Remove 3 internal screws and 
one from underneath to release the deck.
Bad REW/FF due to slip clutch under the deck cover plate. 
Remove that pivotted plate and top cover - remove the facia then 
prize away the 4 brass engagement nibs.
Mark parts before removing
 innards 

The sliding head mounting plate needs the retaining strip 
removing and then lift and angled to remove 
and replace, no hidden balls under this top slide. 
Turned the pulley tyre inside 
out. Poor eject due to thickened grease on both 
the pinch wheel carrier posts not allowing 
the head carrier slide to drop into eject position. Note position of 
springs especially the downstream one with 2 opposing 
springs and clean out all grease.
220mm long second band kept falling off, 250mm 
is too long , 230 mm belt also sometimes fell off.
This deck uses double capstan drive and not much 
stops the second band falling off. If too much 
tension to pull the belt laterally one way more than 
the differential force to ride the hump on the pulley 
then it will fall off. Glued thin celluloid discs 
to each of the flywheel/ pulleys.
This deck in record , monitors playback, rathe rthan 
direct from source so nothing on VU or PPM 
meters until end of leaders

Aiwa AD  WX888 , 1997
 found while trying to make sense of
strobing a capstan to set the motor speed. An Aiwa with rotatatable head for
playing the "reverse" side of the tape. Spindle to one capstan was 2.49mm
diameter and the other 2.69mm and proportional size difference to the
capstans, driven by the same band. I'd measured one spindle  and then marked
,for strobing, the other capstan. Both decks , Rec/Play  & play ,this same
mechanical disparity.
Another oddity with this 1992 Aiwa AD WX888 - end of tape sensor. Instead of
a follower that moves with increase of tension in the tape. This uses the
same small holes in the cassette but is a fixed lump of plastic with 3 wires
coming from it, not coils. 
Probly diode and photo-resistor, diode on DVM and varying ohmage on another
pair of wires, on varying the ambient light . So would only detect  leader
join, not active in the case of a tape jam
I wouldn't say it was a slight difference as in the ratio of  2.49 to 2.69
but not such a large difference I had noticed in general handling.
Probably specious accuracy as I did not remove them for good perpendicular
measurement but 44.86mm and 48.79mm of the capstan flanges. Figure-of-S
shape for the band between the flanges, opposite rotational distrection,
only one engaged pinch-wheel at a  time of course. .
A lot of motor noise as running free with stretched belts. 
Beware of th eeject linkage dropping out when removing a deck. 
Undo Bk,W, Bn wires to give space
2 sc either side of back plate. Replacement band needs negotiating around the "H" speed pot. 
As found stretched bands 230mm circ x 4.5x.45mm
No other rubber seen othe rthan pinchwheels
Found a band to make measurement with . Mark a capstan and the band with white 
mark and count turns and extra run , measur ecapstan diameter. 
Unstretched length 220mm , stretched 237 mm, 7.7% stretch
Disconnect power lead of th eother deck to avoid free running motor noise . 
For th eother deck a silicone band cut using the calipers cutter method, 1x 4mm wide. 
From flat sheet so diameters 68 and 76 mm.
Placed a 1mm washer under one of the motor grommets to tip the motor spindle , "inwards" 
towards the centre of motion of the drive band. Then a nylon toggle actually the cable grip 
from a mains plug - a nylon rod with a hole at each end. Then some rubber cord , one end 
tied to the chassis ,passed through one hole of the nylon, looped around the motor , through 
the nylon again and loose tie off. Adjusted the loose end until the band rode centrally 
over the motor pulley and tied off properly.
Well heads rotate perfectly well on both decks , but going in
batches , for each deck, either tape will not change direction , or will
work
consistently ie unreliably, mostly unreliable.
Drops into an illegal mode where both spools are powered in opposiste
directions and both pinch wheels are engaged , so likely to stretch or
break tapes. This action is initiated by a solenoid then PTO mechanics ,
perhaps one flip for normal play in whatever preceeding direction set before
stopping . Then longer pull or 2 pulls or something more complex
to change direction of play , not explored yet manually. Could this rely on
a timing adjustment somewhere that would apply to both decks ? I have
replaced both drive bands and the speed of both decks is as good as I can
get them via strobing and test tape.
There is no preset associated with the solenoid energizing area.
With bench 12V to the motor , manually pulling in the solenoid, under the
motor ,produces Play mode in normal direction for duration of soldenoid held
in.
A momentary pull and release flips the head rotor to reverse posistion but
deck stays in neutral.
A pull in , partial release, pull in and hold , engages Reverse Play.
Pull in momentary , full release momentary, pull in and hold , normal Play
I sometimes manually have been able to put it in the jam mode, easier if
driving the motor off 4V or so, but not at all obvious what is different in
that initiation.
I'm wondering if a wrong voltage is getting to the solenoid, either pull in
or maybe a negative pulse for the partial position. Whatever the solnoid
drive is, then if it is wrong then would explain why both decks are
affected, lack of lubrication or wear on the most used Play-only deck would
not throw up this jam mode on both decks.
I won't try scoping these solenoids as I've spent enough time on this
diversion and the owner is happy with just normal Play with both decks.
Perhaps both replacement bands are just not tight enough and slips on the
PTO pulley enough to mess things up. As the replacement bands were spot on
the existing motor speed preset via test tape and strobing , I will just
roughen the PTO pulley of both decks and leave at that. The slip clutch
inside the PTO pulley seems slack to me perhaps, something else to consider
if there  should be a next time.
I don't know if it comes under William of Occam's raison (13th century
Occam, Surrey , England did not have razors at the time - later
mistranslation from French) or the more modern version K.I.S.S.
Roughening of the surface of the PTO pulleys returned reliable service for
normal/reverse play modes.

Aiwa ADWX999 cassette deck
No tape functions on one deck.
The motor had broken.Replaced but to 
reassemble, also for just changing drive band .
Loop the band around all 3 pulleys and then with 
2 pieces of thread at either end around the solenoid 
and through the rubber band tie tightly into a knot to give 
clearance for the motor pulley.When reassembled 
cut the threads and remove remnants.The motor speed 
adjust is not in the small hole in motor casing but 
on the adjascent PCB. Before replacing bands 
make sure the mechanism is in neutral, ie no 
power take off engaged by powering up and turning pulleys.
22.4 Hz strobe for capstan with 2.69 mm spindle , calculated speed of 22.4 Hz 
so no adj needed.
Stainless steel clip with right anglesd sections that lay over the spool pivot bushes 
had lifted and was jamming against the sliding deck plate so could not play. 
Move back and hotmelted into place .
Motpor end solenoid hand activated for PTO for slide plate and play.
other solenoid for FF

Akai CS F11 audio cassette
Very weak REW and FF
one of the motor driver transistors marked 1012 was blown.
Also 2 of the preceding trannies marked 808 were blown.
Replaced the 1012 with 2N2222 with 2 pins swapped around and 
the 808 s replaced with MPS2907 also with 2 pins crossed over.

Akai CS 702D tape deck, 1977
Intermittant no rec on 1 channel
Swithc problems the main 14 way R/P switch 
and the rear line/DIN switch.
Renovate as per tips files.
Reassembling R/P switch force back the spring 
a bit before closing the tinplate shroud.
The rear switch can be forcibly removed , bending 
the pins a bit, without dismantling whole deck.
Ball mill slight grooves on upper face of the pcb 
to make re-assembly easier.

Amstrad 7070, 1976, tape deck
motor boating sometimes one ch , sometimes both with no deck functions.
Removed 2x3x9 way switches, renovated.
2 sets of contacts neares deck were a few ohms due to hard grease
Idler axle, pull off end cap with spring, remove tyre and 
replace inside out.

Beocord 1100 2612
play button , not stay down
autostop solenoid keeps operating if play held down.
5TR5 BD137 s/c, 30V on collector

Blaupunkt London SQM 37
Tape rejected after a couple of seconds
Firstly removal of front pannel knobs to remove pannel and then tape deck.
The volume knob ;2 thin spanners or similar cut plate one against the pannel for 
protection and the other to lever between knob and spanner as vacuum seal between 
knob and shaft,the 2 small knobs need the clips depressing at the rear of the pannel 
before puling off. The fault was caused either by the microswitch trigger that senses the tape carrier 
in play position out of position or wear on the main mechanical latch.This latch is much 
like a conventional mousetrap and the lip that holds the main arm when the solenoid is 
powered was worn so ground back slightly with a smal grinding wheel.

Bose Acoustic Wave music system, 1987?
First one?, no model number seen. Cassette deck and radio, no CD.
I've got the ps section removed but cannot get to the cassette deck area to replace the belts etc.
Like monitor casings, but where to release plastic catches? 
Could not be easier, with hindsight. Unlike later Waves, remove the telescopic antenna mounting screw. 
Yes, no arrows here. I'm surprised how firmly the top was held in place with just one screw holding it there. 1987 date probably. 
The acoustic waveguide stuff in the middle section is plastic welded together .
1987 on the deck motor. Perished pulley tyre, 1,2 or 3 "O" rings will go in there. The drive bands are just about working order, at least I can measure unstretched lengths before replacing with sliced silicon rubber replacements .
5 large sc under and prize off front cover, not required for the tape section. 2 cr ms sc at h/s and unplug 4 con 6 black, 3 crto remove bass 
driver. Antenna sc and 2 sc to lift off.
3sc to lift off LCD pcb
GEC deck screws and unplug 3 after marking cons.
Undo cassette flap spring and 2 of the 3 sc of fixing bracket at rear 
to remove the flap.
Prize off white "rivet" to get to perished tyre 12.6mm diameter O ring stretched over 14.3mm
bands as in use on way out, 150mm .9mm sq,190mm 1.2mm sq, 3x.45x263mm.
Spindle 2.49mm . Sq root(D*D/2) with calipers to mark 4 points on capstan and enlarge with tipex , for strobing
Band length 56.4mm diam, 9mm centre , 80.5mm
calculate stretched length 271mm

Golding 602 8 track
1 channel o/p only
One of the 2SC1013 running hot but it was the 2SA623 of the pair that 
was about 5 ohms between C-B. These Mitsubishi trannies have most 
unusual pinning C-B-E. Replaced the A623 with TIP32 with one of the legs 
crossed over to match BCE to CBE. The 2SC1013 out of cicuit was about 15M 
between B and C replaced with TIP31 reconfigured.

Japanese 8 track tape
Marked JS-1 on the pcb. Sticking solenoid action disabling track change and bent leaf switch 
disabling startup.

JVC CD1740 tape
Drive band slipping.
It seemed there was an impossible "operational window" between 
a band tight enough to not slip on the drive pulley and too 
tight it disengages the driven pulley from the take-up spool.
This driven pulley is on a pivot activated by an arm and a 
torsion spring to hold it against the spool. Slid a tension 
spring over this arm and anchored off on the chassis to give 
more "torque"

JVC KD10B, tape , 1978
Bad function, someone had replaced with new band but too large . 
Replacement somewhere between 254 and 302mm circumf. 
2.5mm spindle , 24.25 Hz (divide by 4) by strobe and f-meter sig gen, so left as found speed.
Flap damper slipclutch is inside ratchet wheel. Squirted in some oil as did not fancy 
disassembly. 
Returned years later , still being used in 2011, with a broken plastic cassette flap latch peg.
At least a stub remained showing position otherwise it would be very awkward to align. 
Drilled 1 mm hole to take a PK and a Hama bead. At first failed to latch without tapping 
the flap, but soon wore in.

JVC KD A22, 1980
Loosen mains selector to get at the deck back plate 
and parallel jaw pliers through side and for easier re-banding 
replace with a packed out longer screw there and for the long 
screw grind slots in the head to make easier next time
Second use of Silicone bakeware flat drive band. Bulbous drive pulley 
6.5mm wide so band must be about width/2 plus 0.5mm. 
Unstretched distance 265mm
Blue silicone  band 4.75mm wide, 1.4mm thick , 236 mm circumference, 1mm 
holes 6mm apart near the centre line
1mm thick flat sheet rubber band, 3.5mm wide , elongation 70 percent 
for 500 gm, circumf 227mm. requiring hole spacing of 2.5mm to 
compensate for differential stretch.
Comapred flat sheet band and silicone bakeware canted band and no audible
difference but stayed with bakeware one as less holes required 
and thicker and so probably more durable. 
There was FM noise rumble on the sound due to these bands being 
too tight and bearing noise transfering mechanically 
to the capstan. In the end used a longer flat rubber band without 
piercings and canted the motor a bit to compensate.
Removed one of the 3 mounting screws and replaced with a longer
2.5mm bolt and sleeve and packing to be able to shift the rubber 
grommet position. With tight side of band nearest the motor 
then tilt the motor so the slack side is tighter, only requires a 
set of 1mm or so from normal posistion
Because of the set in this band, not usual flat band, it is very difficult 
to feed around the capstan, wege one bit in place , with capstan ,
against part of the deck structure and then feed around 
the capstan

JVC KD D30 Cassette tape unit, 1982
No tape functions
It looked as though the motor had failed in that disconnecting 
and putting a meter (low load) on the supply to the motor 
showed 12 volts.With motor connected showed about 2volts 
across motor.The low side of the motor is principally via a leaf switch 
on the deck which was failing to close on tape functions. 
Brown and light blue wires to near the solenoid, 20 to 30 
ohms across "closed" contacts.
4 motion buttons , not the pause, activate 
the switch which stands at something like 100K ohm.
Bent back the static leaf and reinforced the outer edge 
with hot-melt string. Maybe the contacts are not the type to 
take inductive start up current.
Turn flywheel clockwise to engage eject function.

JVC R-S33 1981 
Distorted sound on one channel on low to mid volume ok 
above that. 
Sounded like offtune radio station. 
Infuriating fault to track down. By isolation and monoing signal and 
checking backwards from power amp. Eventually traced 
back to the balance and volume sliders. Balance central and commoning both 
vol pot o/ps to Left op was fine on both channels 
commoning ops on right slider then distortion both 
channels low vol. Isolating this pot seemed fine with DVM 
resistance. Breaking open there was some gunge 
between part of resistive and conductive tracks 
having a capacitive ? effect. Cleaning and replacing 
and distortion gone.

JVC RC XC3BK, 1996
stretched belt
11 long screws , 2 under labels. 
Remove tape section first when inside. CD section released by rear catch
unclip small pcb and ps wire
4 +1 sc on pcb
6 sc on motor panel
unloop 2 belts and hook over 2 convenient flanges
2 ribbons mounting brackets
remove sub bracket that fouls small projecting return kockey wheel (2sc) 
may have a spring under this isolated and somewhat hidden pulley
Lift metal panel by releasing black plastic pawls.
Mark band paths on the metal before going further.
Leave 2 plain smaller pulleys in place , no cogs on section 3
Check all pulleys moving and no belt twists after reassembly.
All main pulleys alternate rotation sense. Outlier pulley rotation is 
counter to its nearest main pulley. Both slip clutch pulleys rotate the 
same sense.
Reinforce all ribbons before reassembly especially the 3 that will interfere with the other 
part of the casing so hold down to the pcb edge with a long length of  cloth tape 
and leave inside. Ribbon that passes thru pcb slot, make connection before 
joggling into slot
Band posistion nearest motor is tape A
Assuming a direct replacement is unobtanium. There is no standard for the
rotating mechanism and at leaast 3 headforms: normal , half width R/P plus
E, half width R/P. But there seems to be a standard of the heads, all I've
checked are set in 15mm Al cylinder with 11mm centres fixing holes. Anyone
ever swapped these integral with head ? if required to actually swap heads ,
what is the best way to unglue/unbond the resin/glue seating them in the Al,
heat? Maybe different front/rear-axis length. At least reseating replacement
head is not as critical as VCR head placement. Azimuth setting screw seems
to be the endstop for the rotating mechanism.
Don't forget the 2 pin ps connector on reassembly
beware of bending red LED out of position

JVC TB W11 Tape deck.
No mechanical functions.
Voltage regulator excessively hot due to the motor 
taking excessive current although not seized.Replace.

Kenwood KX W4060
Both decks tape jam ,nasty clicking noises and chewed up tapes
Gummed up slip clutches whether from someone spraying something in 
the decks or as it was a white deposit if it was migrated over ample white grease gone funny.
Also the smaller drive belts may have slackened and as the stretch in these 
is the return action of the pivoted cam plate could cause problems.Also the 
leaf switches are very flimsy and one was intermittant.There is a resistive coating 
to the contacts so not 0 ohm.To get to slip clutches:mark relative 
position of pivoting cam plate relative to the locus cam cog before removing.
To check the decks removed from the m/c activating the solenoid from 
neutral position is first play then fast then neutral.For reverse play longer 
pull of solenoid from neutral but if not long enough then reverse head and 
pinch-wheel engage but forward take-up spool engages.
The ribbon cable connectors are disengaged by prizing the end clips outwards to release 
the grip to move towards the ribbon.Use the edge of the pcb as a fulcrum for a small screwdriver to 
do the prizing.

Kenwood X85 Tape unit 
Broken drive belt
Have to disassemble the eject arm and remove the 
tape mechanism and desolder the 2 long connector pins 
to the solenoid not the shorter hall effect sensor pins 
to gain access to the complete belt path.

Marantz SD 255, 1986
No REC as PTO is too much for the stretched band
Undo REC quadrant arm screw and tape out of the way with link wire in place to long sw. 
Rel;lease front-back tie bar
Mark placing and undo headers
Remove front panel enough to undo 4 sc and leave LED panel in chassis. 
Remove the 2 decks as one on front panel
Mark the fixed REC arm plate before removing
Remove 2 brass sc in slide way of door catch so the motor plate can be bent away to give 
enough space to remove capstan etc. 
Properly probably undo locked nut of screw holding the damper tube and fully remove back plate. 
2.5 x .45mm x 180mm circ. as found 
other co-axial to motor is 1mm x 130mm , wide belt nearest motor
band off capstan is 1mm x 125mm
I don't remember seeing this before. Instead of baluster/bulbous pulley or
capstan, two angled faces with a thin ridge in the centre on the drive
pinion. So the belt must ride on the ridge but why does it not hunt about?
There is a limiting flange either side of the angled flats and the width of
the rubber band is greater than the distance between a flange and the
central ridge, but still why no riding about?. Then what I thought was crude
construction is probably part of the dynamics. The capstan is 2 discs fitted
together but one is 49.94mm diameter and the other 50.04mm so this step
change must make sure the band rides over the ridge but biased to one side,
lightly touching one angled face, but not touching a limiting flange. When I
get the mechanism working again I will try viewing with a xenon strobe light
. Anyone any input on this ? more or less prone to changes in rubber
restitution/stretch etc, more/less likely to come of when PTO is engaged,
greater/less accuracy in speed of drive with varying driven-side back torque
etc.
100R, 68R , 2x 78M12 , 2SD313
For play deck undo 4 sc to remove the deck to get to the brass sc 
properly without bending back plate. Heat off the nut of the air damper tube and remove the bolt
Spindle 2.19mm
Thought for future , an O ring stretched over a brass cylinder and 2 more O rings as limiting 
discs , glued in place, maybe enough to function as a replacement for a bulbous pulley. 
160 mm silicone belt replacement 2.2 x 1.1mm , 270gm stretched to 190mm. 
Original 150 gm to stretch to 190mm the calculated stretched length.
Fit smallest band over capstan pulley. Wide band in place while closing up back 
plate with enough gap to feed around drive pulley. Small rod through holes to 
line up for first sc in the other pair, Fitted nov 2011 for long term monitoring .
1mm bands became 1.3 x 1mm
original small 140 gm to 2x 70mm
longer 200gm to 2x80 mm
replacement 150gm to 2x70mm and 240 gm to 2x80mm
Gap motor to pinion 1.55mm movement, 1.75mm max spindle movement
details of ridged pinion 12.6mm diam ridgex .5mm , cones 11.6 to 11.9mm 
diam , 5mm , original 5mm belt would not wedge into either gap , same with 
new belt although 2.5mm wide it is 1mm thick so angled 
Capstan marked and strobed to 27.52Hz for 4x rpm 

Marconiphone  4246 ,1970
as Ferguson
Transport but no audio
One f the 18V rated electrolytics had failed,  on the schematic as 19.3V 
rail. Turned the spool brakes upside down as worn down. 
o/p devices marked ATES AC142HK and AC141HK in schema as OP1A and OP1B
Some BRC / Marconiphone / Ferguson generic cross references
 as the info does not seem to be out there.
Late 1960s / 1970s transistors, from a few Newnes books, some duplication it
would seem in lower spec uses
AF1 = BF187
AF2 = BC109
AF4 = BFY52
AF6 = BC107
AF8 = AC128
AF11 = BC186
AF13 = BC186
OP1A = OP2A = AC128
OP1B = OP2B = AC176
RF7 = BF194
Some complementary pairings of the time
AC142, AC141
AC154, AC157
AC188, AC187
AD162, AD161
AC186, AC131
AC153, AC176

Matsui STR626
Another burned out 9V motor.
Replaced with a 12V motor ,but disconnected the pcb 
mounted speed monitoring section and added a 10K multiturn 
trimmer

Minidisc player repair notes from "Arfa Daily"
Never ever use 'cleaner' discs - not that I recall ever seeing one for a 
mindisc anyway. They invariably never do anything to help, and in the case 
of DVDs, I've seen them cause expensive damage where the little 'brush' 
hairs embedded in the disc, have caught in the lens suspension, and mangled 
it as the disc has then rotated. I used to do a lot of work on Sony MD 
players, when a guy that I did work for was a regional service centre. For 
the most part, failure to play discs is down to a worn out laser. Sometimes, 
you can get around that for a while, by resetting the laser parameters via 
built in diagnostic software, but it is a complex and tricky procedure to 
do. Another thing to check is that when the disc is loaded, it is free to 
rotate. I had many examples where the turntable had been pushed down on the 
motor shaft, until it jammed the motor. Another very common problem was 
'crap in the works'. The sled drive comprises gears with *very* fine teeth. 
The slightest bit of contamination in them, is enough to stop the gears from 
turning. The contamination in question, often seemed to be very fine sand, 
but I guess that it could have been 'pocket grit'. Just one grain in one of 
the gear teeth, will jam the mech and stop the laser from homing, which will 
result in the disc failing to spin up, and the TOC not being read. Finally, 
I suppose you do actually see the display come up and hear the disc loading 
as though it's about to do everything normally ? I have had cases where the 
door-closed sense switch has caused problems. A word of warning though. You 
need to have the patience of a saint to work on these things, and some very 
fine tools, including a quality set of Philips jeweler's screwdrivers, and 
pointed tweezers. Magnetize the screwdriver first. The tiny little screws 
are no bigger than an ant, and easily lost. Work on a large sheet of paper, 
and use a strong light, and a magnifying glass. And you need to be able to 
hold your breath pretty well, also
 Sony players seem to suffer 
from either contaminated switches on the mech, 
the contamination comes from the flexible 
mounts of the mechanism, and can sometimes be seen as a brown 'stain' on 
the metal work.
Or the tiny 'levers' on the mechanisms which engage the switches.
Mangled heads, no doubt due to 'finger trouble'

Minifon attache early cassette recorder. Swivel cover away 
from spindle, for stuck tape, pivot is on the other end

Minifon P55 wire recorder , pocket size of mid 1950s
Anyone aware of any pitfalls for the unwary renovator? Its been in an
English garden  shed for 40 years. But all mechanicals seem to be ok
,despite patchy rust and grime. Spool bearings and sprung tri-ball retainers
function, "winch-winding" head up and down mechanism works, motor turns by
hand, "capstan" cylinder rotates, and deck slides across on piano key
activation.
All rubber parts perished. One electrolytic has its aluminium case corroded
to dust.
I intend getting just the mechanicals in working order , hook the play head
up to a modern tape recorder amplifier to hear what is on the wire drums,
before looking at the electronics proper. All 3 peanut valves and all the
rest of the electronics seem to be present. At least the previous owner
removed and discarded the 3 batteries 40 years ago.
There is one brand new Protona set of spools with security tape around the
outside of its case but also yellow thread with Protona logo stamped lead
seal on this thread linking the spools. What is that security aspect about ,
I cannot find a www reference to that.
much prettier looking one
http://vintage-technics.ru/Eng-Minifon_P55.htm
anyone know of a www higher resolution version of the schematic on the last
of the second page?
user manual
http://www.cryptomuseum.com/covert/minifon/p55/files/p55_manual.pdf
better resolution schematic
http://vintage-technics.ru/Minifon%20P55/1/Scanned-P55-1.JPG
Nothing cracked as far as I can see but I'm aware stress can build up
in this sort of plastic and sometimes literally explode to fragments/dust. I
was wondering if there was a way of passivating this potential problem or
monitoring for it.
I didn't know what sort of plastic. I knew an antiques dealer once and she
had a plastic grill on a Dancette or something distintegrate into pieces on
moving the cabinet, not touching the grill. I once witnessed an old Thermos
vacuum flask cap explode with a surprisingly loud bang when the sun got on
it, disintegrated to dust and tiny flakes.
I think I can see the original problem area as someone had loosened a screw
in that area . The stop slideway works but the rewind slideway is jammed.
The piano key pushes a quadrant arm that pushes the spool-swapping slideway
for the drive , the quadrant is not turning but not due to 40 years of rust
probably.
Does T on the schematic translate as nano as in nanoFarad and how does A
arrow W of the switch posistions translate to play/record or engaged /
disengaged or forward/rearward
I'm starting to find differences from this schematic
http://vintage-technics.ru/Minifon%20P55/1/Scanned-P55-1.JPG
orientation of triple ganged master switch is different
I cannot find the fast acting switch parallel to the seriesed end or reel
switches
The Minifon peanuts were England make but
HIVAC. As this is rebadged EMI Emidicta then perhaps the sales tax dodge.
I removed the steel circlip and steel washer , both now replaced without
breaking as surface rust only. Circlip holding that quadrant arm in place
and now got that slideway working, latching in both senses. To replace the
drive band needs the "capstan" cylinder anchor, near that point, removing.
Interesting slip clutch inside the steel cylinder , inferred,  not seen. One
of those spring clutches , freewheels one way and low take-up of torque the
other way.
I can see why the 2 end of reel switches are in series but not why that
"switch" is in parallel with another one , the fast acting one, as it will
do nothing unless at the end of reel , which has to act before the fast one
, so what is the point?
So a mistranslation, for "fast acting" read short duration momentary on.
There is some sort of leaf switch under the master sw bank although I cannot
see any wire to it without removing the master sw. This is activated by the
stop slideway.
Indeed, should a reel stop, with the end of wire spring-out lever touching
an end sensing switch then the motor would be locked out without such a
fudge or manually turning the spool.
Presumably p19 of the user manual about the red light coming on at end of
spool.
user manual says , for wire breaks, just knot the ends together, I may try stretched
PTFE spaghetti tube for butt joints of the wire breaks, if interesting
contents.
Low heat and stretching reduced 1mm outside diameter ptfe tubing down to
.5mm diameter. Easily passes alonwire-sense through the eyes of the
tape-head. Hopefully superglue would have enough binding with the ptfe and
recording wire to make a joint.
motor diode , black with yellow dot and leads on one side read ?D3 , 
early Ge diode, first was 1946
part of the complex drive mechanism is a steel barrel (with torsion
sprung pulley at the centre so when it stops, the mechanism rotates
backwards to reset the end-stop trigger position).
The barrel has an axial  1.2 mm diameter pin each end that sits in an end
anchor of a hollow brass cylinder each end . These cylinders have a sprung
loaded pin inside them but there is no sign of any bearing material. Running
lubricated there is too much resistance to rotation. Robbed a pair of 1.1mm
balls from the tiny ring bearing inside a scrapped VCR pinch wheel. But
there is only 1mm or so of springing at either end so again not free
turning.
What may have been in the ends in the 1950s.?
 I will next try rolling a ball of PTFE tape or a 1mm disk punched from PTFE
but what would have been in there , bearing in mind German engineering so
would not have been steel faces bearing crudely against steel at either end
, surely?
Feeling with a needle , the sprung bits of steel are curved, I think, so
original balls in there but fixed intentionally, or by rust, to the spring.
For ease of assembly , they were probably spot welded together. Like the
ferrite carying ends of springline/joy-spring reverb tanks the springs are
then soldered to the brass cylinders at their fixed ends
The problem was one of the anchors was slightly out of alignment , in one
attitude , by a couple of degrees and so the rotating pin of the barrel was
binding on the brass of an anchor.
I've got the motor, governor, weird drive to spools and
"counter" and tapehead lifter mechanism all working at a regular (strobed)
rpm .
8.7V on motor supply + ve dark blue wire and batt negative to turret tag behind 
the vol control, where the reel end-stop switch line comes in, 80mA and 86mA at 10V, 
problem on governor contacts and sluggish/ jerky motor and green lamp lit.
motor wires 22R bk-bn, 25RR-Bk
Lamp comes on up to 12V and jerky for a while then 85 to 93mA and very slight 
green but steady 3.6 to 3.8V dc over motor.
meter touches red with 6V supply.
Small drive belt added and barrel introduced and its end pivot screwed in place.
With 11V ps , higher current and no green lamp and then the motor stops. 
Internal torsion spring in the barrel then makes the motor turn backwards with power 
switched off. 
Tried spinning the barrel from a modern motor and the Minifon chassis hanging upside down under 
this external motor, running for an hour , along with lubrication , but no change to the 
binding
with ptfe discs 124 to 127mA at 12V 
With small pliers flexed the mount in different planes while monitoring 
the motor current to find minimum current dram and realign the barrel bearings.

NAD 6325 cassette
Intermitent failure to play and 
dropping out when playing.
Corrosion on the contacts that sense tape-in,
second from the left edge. Cleaned this and 
the adjascent one and the deck-slide in contacts 
on the deck area.

Panasonic RQ SX10 "walkman"
No play function
Stretched belt not giving enough torque to the head
activate / change mechanism.To gain access,remove
outer casing,screws holding the pcb,unplug the head ribbon cable
from the pcb socket and desolder at 6 points-3 on tape in / type
leaf contact connections,2 solenoid pins and one battery connector.
Hint for dealing with these pesky things,because of the watch size screws
etc do all disassembly and assembly in a high sided tray to catch any
dropped parts.

Philips MC20/22 compact audio , 2001, CD cassette tuner 8x5x7.5 inches
Solenoid - shorted turns, not failed drive belt. Motor whirs but no functions.
Not where I've ever seen one before, the trigger actuator for power take off
in an audio cassette deck. Obviously overheating (copper coloured wiring 
at ends and brass looking at hottest central section) but no obvious burning ,
probably buried. Measures 4.1 ohm but by calculation for 38swg wire and
possible range of inner core diameter and layup packing factor between
regular Pi/4 and stagered layup optimum of (sq root 3)/2 comes out to be
range 16 to 43 ohm. So will have to countoff/rewind. 38 swg enamelled Cu
wire data 0.018 sq mm area and .776 ohm / m.
Unwound wire, burnt buried section, and 23.5 m, now measured 19.2R.
Working backwards with known former diameter then packing factor 
about .75. 995 turns of .17mm (miked as just touching/grabbing in the faces) 
and measured 22.1R. 11.5V maximum over the solenoid. Replaced blown pnp 
SMD topcode 5131 with pnp BCW67 , topcode DC. To remove the solenoid  
without removing the trigger arm mechanics, Prize up and out the plastic section 
from the steel chassis part, leaving the plunger in place until 
the solenoid is out, Trigger arm end partly melted so on reassemble 
added a ring of 1mm copper wire to take up the slack and solder ends together. 
"reamed" out the melted section of the former with a 4.2mm drill bit, plunger was 4mm.
Acess into main body. Remove tape pcb and underlying black 
plastic frame, desolder solenoid and unclip leaf sw pcb. When reassembling 
actuate mechanisms by hand to make sure the middle leaf sw 
arm is out of the way. Similarly with final asembley , if door won't open/ 
close properly or cassette will not seat then power up and will reindex the 
mechanics. Remove base and transformer before refitting ribbons (reinforced with 
proper cloth tape, not gaffer). Cover the poorly shrouded earth sopade before powering.
polyswitch / reset fuse MF-R110 (see tips) added in series with 
replacement solenoid winding.
Rubber drive belt characteristics taken while in there, 170x4x.5mm 
extension 800gm 85 to 120mm doubled up, measured stretched path as 183mm so 7.7 per cent stretch.

Pioneer CT5, 1981
To get to main belt
Remove deck surround, black vertical cover , eject link 
and hidden screw, other screws. 
Remove 3 screws for back plate to 
shift enough to move belt under, about 205 mm , stretched to 216mm 
flat belt. If replacement belt is too thick then 
pack out right hand pair ofdeck mount screws with 
washers to avoid rubbing on base.
Dish out if necessary for more clearance. 
If motor axis bends off line then pack out under 
the power connection point with some glued in rubber

Pioneer CT 70R cassette deck
No play or direction reverse function
Remove tape deck unit from chassis.Remove the illuminated 
back plate to the cassette carrier.A yoke made of cast junk zinc metal had sheared 
where the pawl engaged with the cam wheel.
This material fractures with a characteristic granular structure 
and as far as i know cannot be sensibly repaired.Beware of losing ball bearings when dismantling.

Pioneer CT200 Tape deck
Incomplete erasure and low level of record signal.
Bias oscillator (in can) failure due to partially shorted 
turns on the transformer,trannies ok.

Realistic SCP 32,tape player of 1990 ?
plays only but has reverse play and continuous play.
Nothing after being dropped.
The secondary wires on the transformer had broken 
held the core back in place with cable ties. 
Front flap dislodges from plastic hinge points. 
Fixed some nylon rod, with hotmelt glue, on the 
inside of each hinge point.

Repairing audio cassette tape carrier catches.
The latch arm that holds the cassette carrier against
the deck that often breaks with hamfisted use and
other inaccessable catches.The problem with bonding
these catches back is they require fairly accurate alignment 
in X,Y and Z (in scope sense) while usually inaccessable
in the closed state.Using hot-melt glue "string" (see tips file) 
with a small  spot glue the active pawl end of the arm around 
the nib on  the cassette carrier / door. Bury in this dot of
hot melt a 1/3 Watt resistor low ohms (vary to suit any 
available power supply) with fine wires soldered to power 
up later to melt the glue.It may be advisable for X-sense
positional latitude to temporarily place a washer on the nib.
Loop some thread around the eject arm to be able to pull on
when the flap is closed.Tape a thin strip along the upper edge
of the door flap to give a bit of Z-sense latitude.Melt some 
hot melt on the interior end of the broken latch arm and the 
corresponding area on the deck mechanism,close the flap and 
wait 10 minutes for the glue to set.Putting current through the 
resistor and maybe assisting the eject mechanism with the 
loop of thread should let the flap open.Clean up around the 
nib and reinforce in area of original break with extra glue and 
maybe small bits of expanded metal.

Rotel RD251 Cassette tape
No FF or REW
Someone had sprayed lubricant on the main drive belt,
so had reduced the reactive force aganst stretching to that of a 
band of 1/4 the thickness.The logic must go sommething like : 
the tape is running erratically so something must be sticking so 
lets lubricate the moving parts.Washed all affected parts 
with methylated spirits.Access to the band can be 
obtained by removing 2 of the 3 most accessible screws on the 
flywheel retaining back-plate and flexing to leave small gap.

Rotel RD500, 1981 Mk 2
No take-up spool drive
Broken secondary drive band.
Requires taking deck apart. Front from back and 
also whole deck from chasis and as poked through opening 
a matter of removing mains sw sub- panel also.
Remove main drive band to access secondary band - 
2 cogs one way and one counter direction. 
Mark path of the Rec string and solenoid coupling 
before removing.
24Vac and 11.6V ac from transformer
24V dc on ps pass tranny heatsink

Rotel RD500
No tape functions
Stretched main drive belt.The protruding cover to the tape head area is only 
held to the front cover with 4 1mm plastic lugs.Either end of 
the underlying metalwork has a hole either end which can take 
a selftap screw through the platic cover to anchor down

Rotel  RD500 Cassette deck.
Jamming of front panel buttons
Cut two strips of plastic from an IC storage tube,one flat the other L
shaped in section and glue either side of buttons,parallel,to 
constrain the buttons on the inside of the housing.

Samsung SV627 / SV827
Poor rewind and intermittent sections of lower pitch sound 
recorded on tape.
Poor rewind referred to on tips files for "always laced" vcr problem.
To record as lower pitch the tape must be slipping through the 
pinch wheel or pinch wheel speeding up. The top sintered bearing on 
the capstan spindle was worn so replaced as per tips files 
and motor bearings. When reassembling the capstan "motor" 
make sure the hole in the sub - pcb matches the hole in the 
metal chassis or connector will not align on reassembly.


Sanyo M-W1L
Sluggish tape transport.
Replaced both stretched drive belts and rebuilt
mains inlet socket and a case retaining screw spiggot
on the case-back ,both sheared due to impact, using
hot melt glue ,see hints & tips.

Sanyo TRC SB1000
stretched first drive band
Original measured 150mmx.8x.8 , used 120mm x1x1mm silicone rubber band
Pulled up drive pulley and added a dot of hot melt. If the band touches th esteel capstan 
then possible to insert razor blade between driven pulley and the steel and add a few turns of 
wire to lift it clear a bit.
Speed preset , underside of pcb, 255/212R
Strobing with original band and no tape 35.2 Hz (x4 capstan speed) , with tape 33.9 Hz. 
With Silicone band 32.3 Hz 
Spindle 1.69mm and calculating (from 1 7/8 ips) gives a (x4) figure of 35.9 Hz, 
turning preset clockwise (as seen) to 179/295R but 1 and 1/3 semitone fast. 
1KHz test tape of 1.082 KHz so backed off to 251/221R and 33.1Hz on counter
Not fathomed the reason for this anomaly, when time allows will explore on another 
deck. Failed to check the effect of stalling the take-up spool for a second (for any speed change )
Webbing part of carrying handle to the back

Sharp GF990G ghetto blaster, 1982
With owner from new, was told only
100 came into the UK, probably 1982 from numerous IC "2.." datecodes. What
is the use for the "music processor" as no display, but seems to have its
own 3V batteries for memory retention.
http://i32.tinypic.com/10d6yxx.jpg
The front comes away easily , 4 long sc at rear as do the 2 tape decks, hopefully just perished
rubber bands and minor owner-mangling problems
whole blaster
http://www.audiocircuit.com/A-Images/AA-Brands/S/Sharp-SHH/GF-990-G____-F-00
1-932-SHH.jpg
If it is 1982 it uses a very early minidin connector, 8 way, to connect the
umbilical to the music processor (not sound processor)
Surprisingly few hits on Google so presumably rare. Latest date found was
number
.21224-A on a Sharp deck motor , presumably Dec 1982 , so shipped 1983.
Other motor had .21127-A
Back working again, nov 2011,  with all 7 bands replaced with new silicone rubber bands.
I wonder how long they will last. I read last week that silicone rubber is
not as tolerant of cyclic loading,  which dynamic use of this material I
suppose is so,  especially around the smaller drive bobbins
2.19mm capstan spindles 
Perished rubber bands, but one 3.5x .5mm measured 100gm to calculated stretch length of 
2x139mm
6V on motor to test bands
If rattlinging noise try putting a 180 degree flip in the band, usually can do in place 
without taking apart again. If still cyclic rattle from the 1mm bands try different band sizes 
either side to balance up either side of the slip clutches. For one deck the wide belt settled 
off to one side of the bulbous pulley wiht band set either of 180 degree posistions. 
Rattle , evidenced by shaking of the 1mm band due to touching the middle limiting 
flange, as 1.5 x 1 rather than 1x1mm ,flipping the band on that end only cured that
Had to fix .5mm rubber under 2 of the motor mounts to cant over to bring the belt central.
The ridge type of "bulbous" pulley (see Marantz SD255) may be more reliable for flat sheet 
derived silicone belts.
Strobe from the front (ITF) and adjust the 20K of 20 and 5K presets. One deck via pcb holes. 
Owner had fiddled and lost the plunger from the solenoid, one deck only, cuts in FF and REW 
mode, so linkage not seen. Found a core, pulled out spiral pin. Ground a slot to take the 
white plastic , also slightly ground the elbow of the white plastic or plunger would bottom 
out. Added a felt washer , radially cut , and a light compression spring and worked fine. 
Although 4 holes on each deck only 2 diagomnal each seem to be used for mounting in th echassis.
Loss of treble or loss of deck o/p due to poor conacts on function switch

Sharp MD SR60E minidisc recorder
Owner lost power lead and tried pushing on a 
wrong size one and pushed the pin inside.
Comes apart easy enough . There is a tiny black 
spacer/washer on the non-battery hinge end of the 
loading flap, if any others then lost in dismantling, 
not expected.
Note the way each of the 4 
ribbons enter the connector as not all the same, pull closing wedges 
along line of ribbon to release.
To unsolder and remove the 1.5mm pin/ 4mm 
surround power socket undo the 4 pcb screws and 
prize part of the plastic surround outwards to 
allow the pcb to move away enough to create space.
To return the central mechanical section, 
otherwise not directly fixed into the casing, 
position the loading end under the nib that protrudes 
under the closure hook clasp or the flap 
will not close. position the hold button 
correctly before fixing the back on.
To get to the power inlet socket , 2 screws , 3 ribbons and bent back clip 
on the other edge to the power conn to get enough room . Line socket is 
hole about 1.6mm and outer barrel 4.2mm . Beware on reassembly the small 
frail lever switch on the other edge can foul under the pcb.
Feint LCD display reseat uppermost of paired up ribbons. If ythe power conn pin 
is pushed inwards it will ground out on something inside and load the ps
If disc fails to play but does beep and length of  recordiong shows in th edisplay. 
Open flap and reseat the disc.
Mechanical ticking noise during record , also gets onto recording if quiet. 
Sometimes occurs in play mode but not the same part of a disc so probably not a media problem, 
otherwise not resolved.
Beware getting a corrupted TOC by moving the unit while in Edit/ Write TOC mode

Sherwood Newcastle RM-RV_N325
remove sc, pry apart at bettery end, then plectrum along a long side.
Lost the plastric widget from the slide switch, only rests on there.
Small slide sw ,the sliding housing, cut it down to fit, 
a small notch in middle of one side to take the sw nib.

Sony DTC 690, 1993
voltages around IC901 all wrong
p-off link changes from 8V power off to 0V for power on, check at Q928/Q929
928 between 2H/S TO220
All solder points at the rear are suspect, including the phonos but TO220 bad for power loses
remove 7sc under+ 2 rec level knobs, bush nuts on phones and phones level. Distortion of echoey sound bouncing 
from side to side i nthe stereo image, not due to phones socket problem, nerver on both ch at once.
Removed sc on RF amp cover and bad distortion and relay click over and 48KHz disappearing
DAT "video" head replacement?
Sony DAT audio DTC 690 drum assembly/ DOU-03A/ 8-848-567-11
Initially, anyone know how to get the top drum off, I don't want to heat up to separate interference fit , if there is some secret fixing.
Then anyone happen to know if video heads are the same, they look the same via what little I can see of them. 
I can't make things worse. Smashed up heads, probably from foam breaking up / snagging on the silly "head-dirtier" arm 
I managed to make a small hub puller out of an old pair of basic wire strippers and circlip pliers and a minute of low heat from a hot air gun to pull the 6 pole magnet disc from the underside, without damage. After taking measurements of the 2 gaps, to the nearest thou. Next week I'll try removing the top disc from the middle disc, that hides the heads, again interference fit and again nothing to really get a hold of for hub pulling action 
Discovered one thing, so far. There are 2 magnets on the disc I removed. The disc is probably mu-metal with strong 6 pole motor magnet below and a weak thin disc above to energise a castellated pcb track for a tacho. I suppose the mu-metal is to stop the rotating main field from directly coupling with the heads or the transfer coils,one pair is static and one pair rotating relative to the magnets wheras the video heads are static relatively speaking, and the weak one is too weak to affect more than a couple of mm away from it 
I've decided , when I get back to it , to drill matching 8 holes in a plate and hope 8x 1mm screws, 5 threads each, will hold in place while trying to separate the 2 drums 
I need to do a hub-pulling type operation on a small piece of equipment that is not made to be taken apart, so no purpose-made anchor points. There are 8 off , 1mm tapped holes with 5 threads per hole , in the aluminium available (used for undemanding normal fixing to the chassis) , if I drill a plate to take 8 screws . The only screws of that thread I have are brass, probably preferable to steel anyway. For a similar hub-pulling where there was purchase  , after heating (limited as to amount that can be used ), required about 4Kg of force to extract. Would 4Kg , assuming even distributed loading over the 8 screws be above or below the stripping force ?
I found these sites but not applicable for my purpose it would seem
www.tribology-abc.com/calculators/e3_6e.htm
http://www.roymech.co.uk/Useful_Tables/Screws/Thread_Calcs.html 
Yes I would not say they were a tight fit. Decided to suck it and see and potentially sacrifice half a tapped hole. So 3 turns only engaged in one tapped hole and a spring balance, I took up to 2Kg with no problem. So I'm now confident that 8x five thread screws and a compressible washer/pad of silicone rubber under each screw head , will take the 5Kg via an added hole-matching load-sharing plate 
Came apart without problem, Al plate with matching holes, silcone pads and small thin wahers under the screw heads. Frame fitted to the plate and a pair of circlip pliers in the gap to push abainst the spindle 
7x 1mm screws with little washers and pads of silicone under the heads, through holes in a plate with a reaction frame fitted, and screwed to the DAT drum. 40 seconds of  300 deg C low heat hot air and the circlip pliers as a lever and the bottom drum came away. Leaving the ball race on the drive and the drum separating from the outer section of the race. Upper ferrite former for thre upper coupling coil  seems to be glued to the central lump. Desoldered at the 4 solder joins but not yet tried heating the ferrite to see if it comes away. Under that is the head mount screws. The heads are about 80% the size of VHS heads, and certainly thinner, will have to find a scrapped 8mm set of heads 
Here is a rare beast, pics of innards of a DAT drum
http://www.diverse.4mg.com/DAT.jpg
top views of the 3 sections at top, 1mm squared paper and one of the 1mm screws I used.
The ring of white dots in image lower1 is where the middle ferrite disc was superglued? to the central boss. I tried 20 seconds of 300 deg C heat and trying to break the bond with a screwdriver blade, cracked the ferrite, so the splodges are my superglue additions. 30 seconds of heat and a smell of varnish or something and the bond broke. 
I forgot to include the motor section in those pics
Spindle 22.5mm , 7.62mm race face from spindle end (may have moved , unknown ), top disc 
3.84mm thick, lower disc 6.4mm 
I raided an 8mm video head drum. Heads about .2mm thicker (with the pcb sliver) than DAT ones ,probably room , width 0.9mm wider , probably room wit a chamfer on either side. Radial depth would need 3mm cutting off and the fitting hole moved but as no precision there, probably feasible.
Strange, I've never removed an individual video head. I always wondered how the head-coil ferrite could be mounted with epoxy on the brass section with any precision. Now I see they use shims under the brass. The one I looked at marked 76 , presumably 76 microns. I always thought the mounting surface was a reference plane but not so, each head must be assigned a shim , on test, before fitting. No idea whether 8mm and DAT use the same reference plane and no idea how to set the video heads before screwing down in place. When I have time I may have a go at adapting and tryin.
8mm head brass is .2mm deeper with the pcb board sliver, 8mm is 10.9mm wide and DAT 10mm wide
I have to wonder why they did not make the heads disc easily removable like a video recorder and ,so, if there was a cheap and cheerfull generic way of replacing the innards of "over a barrel" company-supplied drums 
Wherever they intended you to replace the top disc of a VCR they always supplied good mechanical fixing points for clamping to, to break the fit to the bearing. Not in this case 7x 1mm , 5 thread deep, tapped holes were just there for holding motor to drum and drum to deck. The threaded holes would be at least 3mm for any mechanical loading in extraction. 
Write protect is active protected with tab inboard, recordable with tab to edge
Difference in ohms readings of heads//coils because of different coil diameters
39 thou clearance between top and bottom drums
57 thopu clearance bottom drum to 3-wire plate to magnet cup gap
NMB on bearing seal , common VCR bearings make
Used Steelex , India wire strippers , type that you pull the plier blades axial to the 
wire to strip, ground off the 2 V cutter parts to leave a pair of pliers where the tips are L shaped and wedged and thin enoughh
, to lodge behind the drum 

Minicisc Sony MR Z90
Dual concentric power connector problem . I've successfully resoldered this
socket connector to the board and come to test it. Owner has the original ps
and lead. The smallest connector of my adaptor set seems to fit, labled
2.35x0.75 mm. Diverter switch works with htis adaptor , socket pin connects
through and outer socket contact connects through (trying with a pin poked
in there) but will not connect with the shaft of my adaptor. Is it too much
of a plastic bead on the end of the shaft wedging the side contact too far
out of the way ? do I need to chamfer it down a bit ?  or do I need
something more like 2.6x1mm connector.
Checked the tiny yellow connector and rebuilt the pin connection 
and resoldered but the diverter switch failed, with the wrong 
sort of power plug. Wired in an external standard size one. 
Owner had cracked the 2 lead ribbon going to the magnetic head, 
scraped back away from break and soldered two vinyl deck arm wires 
in place , back to the pcb connector. Unfortunately the owner had 
fractured the main ribbon at the connector
There's a lot of useful technical stuff on all minidiscs on
http://minidisc.org/
With exploded views off manual on ^ and a bit of 3D jigsaw-puzzling managed
to work out which bit went under/around which, at rear of batery
Coppery spring plate goes over the mag head carrier 
arm and screwed down to the traverse bracket
Slideway sw encases sw (slot in pcb) at rear of battery 
long axis.
LCD+sw 0.5mm spacing ribbon line opposite no 4 from button cell end 
is no 5 in ribbon from button end failed continuity check

Sony cassette player CFS903L
Forward and reverse heads acting concurrently
Linkage to head forward/reverse switch
very puny so broken + worn belt
Broken jockey/idler assembly failing
to trigger end of tape mechanism.

Sony CFS W401 portable stereo
Deck B defunct,deck A intermittant failure to play.
Deck A problem due to flimsey metal linkage between the play 
button and the pcb mounted switch.Bent back to shape and reinforced 
with expanded metal and hot melt string.
Deck B burnt out internal controller in the motor due to excessive 
bearing friction.Replaced with exactly same make and model number 
of motor but poles or tacho characteristics different so ran too fast.
Had to add in parallel 1K resistor between A and B terminals and 
change the pulley to a smaller size before in capture range of 
the main pcb normal speed pot adjustment.

Sony DTC 690 DAT
Mangled tape.
Placing a force guage on the 3 wing coupler of the 
tape spool engagers there was just 60gm on the supply side 
and 55 gm on the take-up. 
Take-up reel has the stouter of 2 springs loading the 
slip-clutch. The drive voltages in different modes to 
the motor agreed with the manual. It seems a lot of Sony 
kit ,including cam-corders ,that use these low RPM motors 
(low audio noise ?) lose magnetism or some-such, so start-up 
torque and drive torque is much reduced. The multi-poles are very close 
together and some may jump / coalesce so overall losing magnetism 
and so torque.
Also the supply side sliding tape guide was not fully 
retracting so snagging the tape when ejecting the cassette . 
Taking the relevent boards apart does not 
disturb any mode-switch alignment. There are 2 slots in 
the slide bar ,one supply side,one take-up side.  Cut down 
a couple of small nylon cable-ties to give a 2x2x4 mm L ,side 
section, plastic to glue into the ends of these slots to take up 
the slack of the sliding guides.
The main problem was loss of magnetism so loss 
of torque in the reel drive motor. Low rpm so low 
audio noise presumably. Gave up at that point but 
considered trying taking 6V supply or something 
dropped from the 12V supply to feed the 2SB TO220 
trannie of the reel drive variable supply. The drive 
voltages were correct and plenty of current 
but just no torque out of the motor which did not 
seem to have bearing problems.

Sony MDS JE510
Needed to clone across to a corrupted TOC (on a Sharp m/c) but this model does not allow 
simple hot-swapping of MDs
Remove large top frame with 4 sc
Remove rear top plate held with one small sc and slot.
Mark the position of the 4 cogs in the EJECT posistion.
Turning cog 4 to bring the drive dog outside it is possible to lift the cog off 
with a bit of  straining. Exposes the single u uswitch and simple single activation line 
on the underside of that cog.
Small dot of hotmelt to the underside of the flipper of that usw and lead out the hole 
in the deck. Tie to a rubber band that can loop around a suitable component on the 
pcb, pulling down the flipper.
Reassembling , the MD will enter but cycles through Welcome/Eject but fails to Eject, 
probably flipper stuck in "tugged" position - free it up.
Remove disc manually after unplugging using a small crosspoint driver in the holes 
of the cog 2 , clockwise to Eject and anticlockwise to inject.
In Ejected posistion the dimple of cog 4 opposite pivot of cog 3 and M on cog 4 between 
main part of deck and a corner of the removed rear top clamp that holds cog 4 in place.
If alternating Eject/ No Disc, turn cog 4 one tooth anticklockwise.
uswitch at end of cam arc so slight pressure via the intermediary cam and an MD 
manually pushed in, moves cog4 enough to change usw state.
If MD starts to inject but jams with cog 3/4 jumping teeth, pull up and rotate cog 4 
one tooth anticlockwise.
To "recover" corrupted TOC of a minidisc in  A sHARP md sr60. Don't quite know what happened. 
17 tracks recorded, as continuous recording,  
and wanted to see how much time available on disc able to continue recording. Seems you cannot 
do this while recording - you have to go to STOP first.
Pressed something like Edit , say 10 minute and 3 minute MARK mentioned in the display at 
diffferent times,
then pressed ENTER or something, or low battery or recorder came to a normal end of space at that point but 
at STOP Er Md something appeared in the display. Perhaps a bug, in that you cannot enter 2 timing marks 
that over-run the available length of recordable space. 
Recovery
JE510 prepared as above with the top frame removed for access to cog 2 
With no microphone make a stereo recording of silence to a blank MD, the full length of the 
MD, this is the donor MD, 8 tracks only for this sort of recording.
Load as normal the donor MD full of silence, pull the thread and lock the thread via a rubber band say around the large cap, manually
rotate the eject gear, clockwise with a toothpick in the holes, to eject that MD, the carrier may need some finger assistance until the MD can be removed from the front, rotate the other way to take-in the
target disc. Go into Edit/name , title as a letter or something, to force a TOC change 
, release the thread and press eject as normal.
Recovered full recording without gaps, in stereo , and as a bonus undeleted
a bit of previous recording on the end. Had to use this procedure another time. This time I'd forgotten to remove a recorded disc, should have put in a blank MD, before using the MD as an isolated (battery powered and a polyester cap in each line to decouple the electret voltage, to use as a stereo monitor in an amp repair, listening to test signals via the headphones. So never actually recording anything, just in PAUSE mode but must have corrupted the TOC as the previous recording session showed nothing amiss going to TOC at the end of that session.
On play the counter incremented as normal, fewer but longer tracks, on playing / off/ 
resume at previous stop point info retained

Sony MZ R55 minidisc ,premature low battery indication. 
Soldered a blob to the -ve end of the custom rechargeable battery.

Sony MZ R90 minidisc battery closure
Presumably a common problem, but new to me,  open to any suggestions.
http://home.graffiti.net/diverse:graffiti.net/MZR90a.jpg
side view
http://home.graffiti.net/diverse:graffiti.net/MZR90b.jpg
mm graph paper
Show the battery closure with the little cover of sliding plastic removed.
L is over the latch to free the plastic
+ is over the really flimsy battery connection which of course is bent away
so no longer making contact. So feeble that there is no point in bending back
 although for illustrative purposes I have for the pic) as it will soon bend
back or fracture.
At the moment I'm thinking of cutting a bit from phosphor bronze shim and
rivet/soldering with an eyelet+tiny washer through that hole marked with an
R and doubling up the existing.
Not possible to sensibly remove this hinged brass as the pintle is rivetted
in by the look of it. 
Worked very well, almost looks as manufactured.
Small phosphor bronze strip from a small limit switch ex-CD traverse, cut
down and bent.
A matrix board "rivet" vaguely crimped over , then soldered to the original.
around that hole , excess solder and rivet pin cut away, and a bit of the
plastic cover milled away , to slide over the rivet head and solder blob. 
Finished mod, with the plastic cover slid back on
http://home.graffiti.net/diverse:graffiti.net/MZR90c.jpg
solder blob toned down with a "gold" metallic felt tip pen
another one
Broken kapton tape to the magnetic head, 4.2R 

Sony MZ R90 mini disc
Owner had tried fixing intermittant display problem by supergluing the ZIF socket 
wheras it was cracks in th eribbon conductors. In the end he managed to pull the 
ZIF socket off the pcb. To free the display pcb , 5 sc, then 
with low temp hot air gun heat the display section while tugging at the pcb 
to break th eglue tape either side of the LCD. 
I removed the 15w ribbon at the other end by low temp soldering iron 
enough to break the solder while tugging at the ribbon. 
One end .5mm and the other end .8mm spacing.
For .5mm end ITP soldered .16mm wires in place then other end normal soldering 

Sony TC FX30 Tape Deck
Play function engages 5 to 10 seconds late.
The play function trips on pressing key but the cam
slowley rotates.Part of the associated mechanism is
a long lever on a steel axle where unnecessary 
grease had hargened or reacted with the plastic to
bind on the shaft.Dismantle and clean out.

Sony TC FX44
No tape play, FF/REW ok
The pto mechanism off the capstan used to engage 
slide mechanism was jammed so lower of 2 solenoids 
could not operate. Assumed due to wide band so replaced.
REmove baseplate to check this solenoid and mech.
To remove whole cassette carrier remove the front panel 
and release the remote socket to expose the screw that 
holds the left hand small steel plate that limits 
opening of cassette flap. Then can slide leftwards 
to remove off pintles. One of the flimsy bits of 
plastic holding one of the plastic "springs" thatpivot and 
hold tape against deck, had broken. Wired a loop 
around the pivot and out to the front via 2 drilled holes.

Sony TC FX44
"Motor-boating" noise recorded intermittently on one channel.
Same defect can be simulated in record mode by removing the cover of 
the relay and lighly depressing one of the made contacts.
Replaced with a sealed DIL DPDT relay but this had a polarised coil 
so had to cut the traces to the coil and reverse the wiring.

Sony TC FX66 tape
Severe low frequency distortion (motor boating) on one channel 
on recordings but no indication on meters during recording
Failure of one set of contacts in the Play /record 
head select DIL relay.

Sony TC FX66
Loss of high frequencies,both channels.
Holding the unit while playing and changing orientation drastically 
altered audio output.
Although the tape head was worn it was not the reason.
The tapehead and pinchwheel sub-assembly is engaged in play 
mode by solenoid action. The mounting of this solenoid had slackened so 
the tape head did not enter the cassette opening fully.

Sony TC FX66 Cassette tape
Dead,the owner reported only the Dolby type number working and 
then nothing.
First problem the thermal fuse in the power transformer o/c. Replaced 
with an external one thermally connected by enveloping in "fire cement" the 
stuff used to seal joints in metal-work at the back of boilers etc.
Gingerly powered up but instead of secondaries of 18-0-18 and 12-0-12 
it was 13-0-13 and 7-0-7 and only the Dolby light.Eventually traced the 
loading of the supply to the transport deck. The spool drive motor unlike 
the capstan drive was surrounded by thin sheet mu-metal which with time or 
temperature had split the cloth tape holding it in place. It had unwound 
slightly and was touching a component lead. Rewound tight and fixed with a 
pair of cable ties.

Sony TC FX66
Tape pulling through capstan/pinch-wheel due to slip clutch 
not slipping. Even cleaning the felt/surfaces made no difference. 
Replaced the existing internal spring (1 Kg force to totally comress) 
 in the slip clutch. 100 gram spring worked but not full tape length in 
FF/REW, put in a 300gram one.
Deck bulb supply with bulb load 4.75V.
Spool rotation sensor is this bulb interrupted to a light 
sensor on deck. The back plate , in the cassettecarrier, 
is vital to this operation to conduct light and must be replaced 
for deck function checks.

Sony TC U5 cassette 
Main drive belt falling off .
An era when SONY used good enginering but 
used plastic pillars to mount the 
drive motor. Over time plastic had 
creeped allowing the motor axis to drift 
and the drive band lie to one edge of the 
capstan pulley rather than central.
Packed out the relevant pillar with a washer.
To remove capstan pivot retaining bar you can undo 
just the one screw to release enough to remove 
drive band.

Sony WM R202 recording walkman
Numerous problems due to being dropped on corner nearest volume control.
The machine would work with rubber bands all around it holding the 
battery compartment on,the cassette in and the play button depressed.
To gain access undo the volume dial with circlip pliers in holes and when inside 
remove the reel nearest to the stop button.When reassembling outer casing beware of 
snagging the ribbon cable that goes to the head and the erase magnet actuation lever.
One of the ends of this lever had jumped so one magnet not engaging and so incomplete 
erasure behind recording on one channel. In reverse play direction there was a rubbing 
noise this was due to one of the plastic cogs rubbing and the axle needed bending back slightly.
One track inside the volume pot was broken so wired across giving maximum 
level on one channel instead of nothing.The pawl on the cassette flap would 
not engage and the other end of the actuator lever was bent and fouling 
the latch so not holding in in play mode. The plastic lugs holding the battery compartment 
had sheared off so fashioned functional replacements from small solder tags 
glued and screwed external to the casing.

Tape decks in general 
Recording of a noise like old scratched vinyl records even onto
pre-recorded and record protected tapes and even tape players
with no record facility.
The click noises are constant with a repeat rate of the speed of
rotation of the pinch wheel.Minute magnetic particles have got embedded 
in the rubber of the pinchwheel and laying a "track" over any tape.
Replace the pinch wheel as probably too soft to be cpermanently
cured by cleaning.

Technics M235X tape
Only REW tape function
Other functions lead to start / stop continuous erratic 
behaviour.There are 2 springs that engage a Y finger to 
disengage the main tape deck slide mechanism.One of these 
springs was to weak to properly function.Also break in 
2 of the leads in the flexible inter-board connector so syscom was not 
recognising 2 of the limit leaf switches.

Technics RS CH770,1966
part of system with ST CH570 and SE CH570
No tape transport - perished small guage drive bands.
To open flaps unpowered trip the latch upwards along the 
edge of each deck.
Unclip front section from rest of unit to undo connection 
between both and lift the retainers to remove the ribbon lead. 
Desolder each of the 4 motor lines and remove 
main pcb. Undo plastic backplate and tinplate screens and unclip the fine ribbon (for the head) 
housing , before removing motor section totally. Fine belt needs pulling 
off around the locus cam follower and grease removed from 
new thicker band after replacing.
DC Voltages on tape umbilical in Play mode, as 2 rows 
relative to earth point on rear
-1.1(12 ac),-.7,-1.1(12 ac) , 1.5,-.3,0,0,0
3.6,3.8,-.3,1.4,-.3,0,0.4
Inside SE CH570
umbilical as 2 rows
-.9(12 ac),-.7,-.9(12 ac), 0,4.3,0,0,0,-.3,-25
-.3,0,4.6,-.3,4.6,0,0,14.7,0,-25
and on RSN 35H1
0,35,-35,0,14,0,-4,-14,0,0,0,0,0,0
The main belt path is the one closed to the front.
The other will work but will rub and maybe squeal on 
part of the mechanism

Technics RS M10
poor sound etc
pilot lamp 6.5V
bad phones socket on one ch. 
marked PAT EX 96BD4 1/4 inch socket. Remove rear closure , 
grind off diametric swages. 
Bad rec pot , logo A in a circle, 619T M100K ohm A
Complex shield nearest bush. Don't forget 
the end stop plate over the central shaft before Dremmel slicing 
into the end , engraver swage back in place.
For band change , undo screw and remove counter frame. Undo screw hidden under 
motor to dislodge clips of motor frame, use a mirror to align for replacement.
Rear capstan plate remove top screw and slacken bottom 2. 
Band data 
using formula on tips files
b=41.75mm ,a = 6.85mm , c=45.5mm (measure to motor hole capstan centre 
on the slant and hole diameter  and pythagoras to determine) x = 87.4mm N=68.2 degrees
Original good band 4.8x.45x328mm elongation 2x164 to 2x194mm for 1Kg, 18.3 percent 
so tension in band (one side) 216gm
Pinch wheel 14mm diameter, core about 5mm hole. 
Both play/rec head and pinch wheel arm can be removed through front without 
removing from the chassis

Technics RS M235
Intermittant lock-up in play mode.
Curious fault condition where good engineering and high quality control 
meets a design flaw.The main locus cam cog is driven by one of two smaller cogs of about 
40 teeth the profiles match too perfectly. When this cog train disengages it is not in a pure 
radial direction there is a partial tangential relative motion on separation.It only requires 
1 tooth (so 1 in 40 occasions on average) to be slightly imperfect and while one 
tooth disengages ,the tip of the adjascent tooth 
can engage with the face of its matching tooth on the other cog and lead to a jam.So ground 
down all the tips of the teeth on both small cogs by a depth of about .5 mm.

Technics RS T130 twin cassette deck
Play deck no play or REW,record + play deck intermittant tape wrap 
around pinchwheel.
This is probably a stock fault after 10 years of use especially as 
otherwise well looked after machine. Probably the same fault on both decks. I will first 
describe the remedy for the rec/play deck as this would only require a 
simple modification to rectify if caught in time. The slip clutch in the take-up 
spool had become too tight giving too much back torque so the drive pulley in play 
mode would slip. Remove the circlip on top of take-up spool spindle and 
replace the interior spring with a shorter/weaker spring. Attached to the 
head carrier slide is a spring attached to the final play mode drive pulley. 
Replace this spring with something a little stronger or reduce the length of the 
existing spring as "belt and braces".
Unfortunately with the play only deck it was a case of one slip clutch binding 
and another one slipping too much. The equivalent take up spool back torque 
had been excessive before inducing final failure of the drive mechanism. There is a another large 
slip-clutch on a 1.5mm diameter spindle. With so much back torque the brownish cog at 
one end of this spindle had started slipping on the pin and the gripping part of the slip 
clutch at the other end of the pin had split enough to break the grip on the 1.5mm pin also. 
Tried reinforcing this plastic disc but didn't work and had to replace with another 
simple disc with 1.5mm hole from some unknown other scrapped deck of some sort. 
With disc of slip felt rather than the original anulus of felt.
The cog end - removed cog and "forged" a flat (wider than 1.5mm) on that end and a 
couple of roughly matching 
knotches on the (softer plastic) cog to give some mechanical purchase. To get to this spindle requires 
partially removing the motor plate and the head carrier slide. When replacing the slide make sure 
the drive pin to the carrier is 
on the correct side of the "safetety pin" shaped actuating spring by moving 
the "quadrant arm" that engages with this spring.. Replacing the 
motor holding plate requires something like a compound winding-on motion to engage 
the hook pieces around the main part of the housing. Finally made the same modifications 
as on the play/record deck to reduce the braking effect

Toshiba RT 80S
Chewed tape.
Firstly the DC switch side of the mains inlet needed 
resoldering on the pcb.
Replaced the drive pulley between capstan spindle and take-up 
spool with a 18mm x 2.5 mm neoprene "O" ring, can keep it in place and stretch over the tangs.
Also increased the tension on the relevant torsion spring 
that engages this drive.
Returned 5 years later with no take up spool drive
That O ring broken replaced with 20x 2.2mm one
Remove back plate over the capstan then remove capstan
2 short casing sc lower front, one long one inside cassette section

TRIO X-5WX Tape unit
High level white noise only on both channels
In area associated with the HA12088 dolby processor was a 
 470uF,10v electrolytic that had gone ohmic.

Wien or Wier 8TD3 8 track tape player.
No function
Sticky capstan spindle bearing due to aged lubricant and a perished 
drive belt.Access to spindle by removing flywheel disc and then cover 
plate.The electronics p.s. is powered by 2 secondary coils on the shaded 
pole drive motor.

Wien 8TD4 8 track some belt data
run some string round the motor shaft and drive wheel and the length is
11 inches (with the string tight) and it's a flat belt, 0.5 inches wide.
Diameter of the motor housing = 45mm, 25mm high.  Length of spindle from
base to top of drive shaft = 15mm, length of drive shaft only = 10mm
drive pulley 10mm, bulbous face to the belt.
diameter of the driven pulley 64mm, flat on the belt face

Yamaha AST C10, 1989 some surface maount
sp 5.3 ans 5.5R
No function LEDs , no function,s, L display and clock functioning.
Not obvious power on button, on the top
To release sp press button under and lift up
side panels extra long pk at front top
mark leads to CD unit before disconnecting
2x 1.6A fuses in centre ok
mark leads to radio and tie together
probably STK 4142 mk2
6 x 2SD2061
boards inside marked SHARP
second LCD display, in CD mode , has bleeding black LC 
splodge on lower part
L tape unit , in normal play, and near end of tape (most torque) will 
drop out
Leave rear H/S in place, just remove the cover for more scdriver room
Remove CD section , then the central cross brace plate, 2 sc front and back, 1 L, 2 R , cut cable 
tie, undo hidden sc underneath with long scdriver rthrough rear vent hole.
Mark and tie off related cables. Beware of eject plastic lever widgets dropping out.
I left front panel in place but perhaps could remove , before 
releasing both tape decks. Undo the band drive motor and bands are easily replaceable.
FF/REW motor is 3x normal length teeth and no slip clutch
L & R bands , not up to the PTO back-torque, measured 220x3.5x0.55mm
and 15mm extension for doubled up band and 600gm loading
230mm silicone thick band too long
Tried width split 212x2.5x1.5mm silicone band with 30mm extension for 600gm loading
Perhaps better centring with a thickness split band about 230x4x.75mm 
Motor needs canting over a bit. Longer 3mm screws, 2mm silone pad between motor and mounting 
and a dollop of hotmelt in the gap to the third pillar with motor running off bench ps, only about 5V , as with no voltage regulator 
connected , the motor will squeel at high revs if 10V or so is used.

Diverse Devices,Southampton,England


Telephone number - the same number as it has been since 1988 
but email is now the preferred method of contact so number deliberately not placed here. 

I devote time each day to replying to emails.

   (obscure/obsolete components,second hand test equipment,
schematics etc)
Postal: 
66 Ivy Rd,
St Denys,
Southampton,
SO17 2JN
England 

There is no point in contacting me about any of the above, the 
repair job may have been done 15 years ago .
I cannot clarify or enlarge on any of the above.

e-mail 
ncook246@gmail.co.....m 
 
 
 A reserve email account is diverse9(commercial at)fastmail.fm. 
Please make emails plain text only , no more than 5KByte or 500 words. 
Anyone sending larger texts or attachments such as digital signatures, pictures etc will have 
them automatically deleted on the server. I will be totally unaware of this - sorry, again 
blame the spammers. 



More hints & tips and repair briefs on
homepage http://home.graffiti.net/diverse:graffiti.net/