Repair Briefs - Video recorders, TVs and computer monitors
The following are repair briefs for various
equipment.The infomation 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 video recorders, TVs and computer monitors.
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.
Modern Chinese saying "If it can be mended,It must be mended"
- Chairman Mao Zedong
Should the location of this file change please use the keyword "divdev7" in
a search engine to find it again
Video Recorders
Aiwa FX1500
Tape jam
With cassette on deck the take up side was held against
the deck but the supply side was not firm so allowing
to rise.This then allowed the bottom flange of the
supply side spool to rub the bottom of the cassette.
So failing to retract tape into cassette going
to STOP mode.Probably due to permanent torsion in the cross
coupling rod that couples cassette motion from one side to the
other. On supply side external to cassette housing removed
large cog and repositioned 1 tooth advanced from previous position.
Half a tooth repositioning would have been better but of course
not possible.It looked increased possibility of cassette jamming
on the housing when in eject position because of skewed action
but it didn't jam once in the access slot
Aiwa FX2500 vcr
Tape jam preceeded by poor rewind
The slip clutch in the swing arm mechanism of 2 cogs
that engages in REW with the main slip clutch was not
slipping enough so changed the internal spring for a weaker one .
Akai VS F30, 1990 vcr
Dead machine
Despite pressing Clock, Transmit on R/C - necessary
after more than 1 minute off mains.
Checked fuseable Rs in ps , ok
and output voltages (later when working in play mode)
21,16,8,9,10,0,5,0
It is possible without removing the bottom plate to
inch round the mode switch motor (in the easy sense ) with screw driver
through cassette carrier. M/c would now switch from standby to
on and work but the cassette was not being held down in cassette-in
mode.
The rack that drives the cassette motion had jumped a
tooth on the pinion so only one tooth engaged
at cassette-in position when it should be 2.
In cassette-out the mode position was in an invalid
spot, outside of hand-pushing the cassette in to activate ,
and disabled the machine until inched back.
Forced back and made mods to constrain this rack
in tighter mesh with cog.
Cut down a PTFE through chassis feed-thru pin complete
with pin and forced into gap between rack and metal chassis.
Fixed in place with plenty of hot melt glue against metal
and plastic chassis sections.
The erase head does not pivot on this m/c and
forms part of rack constraint but only anchored
with one screw. The other head locator just pushes through
a hole in the chassis. Srewed down this bit with washers padding
out so tightly held and no longer lifting.
Checking motor motion, desoldered leads and powered
from 9V, .1 to .2 amp in free movement.
Akai VS8 vcr.
No transport functions
A small spring attached to the solenoid linkage
mechanism had broken.
Akai VS8 vcr.
Dead machine ,no display,no rf output.
Failure of STK5225 hybrid regulator.Originally replaced
with one from an unchecked VS4 but this too had a
duff STK5225 it transpired.Fault due to over-heating TA7245 drum motor driver,
leading to overheating of the STK 14volt regulator section
Akai VS8 vcr
Intermittant failure while playing followed by tape
jam on trying to remove the cassette.
Small solder bridge on the MBL8243 on the ps board
Akai VS-8 vcr
Random unsynced "Venetian blinds" of anti-phase coulour
in the image in PB.Instability / oscillation around pin 2 ,
the VCO section of the AN6371 and 4.4357MHz,taking
a 10K resistor from pin 13 to ground cured the oscillation .
Akai VS-8 vcr
Tape jam in play mode.
The large tyred pulley that engages with the capstan flywheel
had the plastic boss cracked so allowing the steel spindle to rotate
and act as a slip-clutch.Demount whole jockey-assembly ,remove
pulley and strengthen by gluing with epoxy and expanded metal
reinforcement and deform the end of the steel spindle by squeezing
/ indenting with an old pair of end cutters to produce a key when placing
back into pulley.
Akai VS512 vcr
Failure of drum to get up to speed unless "kick-started" with a finger
Failure of one of the poles of the 3 pole motor driver TA7245F on drum motor board.
Akai VS F10
No cassette loading
The half cog that links the cassette operating metal tooth rack
to the rest of the cassette carrier had a broken tooth.The flimsey
clip that locates this half cog on its shaft and rotates
around a curved slot in the metal casing had failed and then misregistration
had allowed the tooth to break.Replaced with a 20 tooth fibre
reinforced nylon complete cog from some other equipment.Opening out
the plastic pivot piece to this cog and using a bolt and 2 lock nuts to
secure the replacement full cog.
Akai VS G245
Mode switch mechanism out of synch.
Small plastic guide peg obscured from view had sheared off.
This peg is under the main mode change rack that goes the width of
the deck. It restrains the reactive force from the small drive
cog on the main locus cam. Replace with a cut down nylon bolt.
Remove remnants of broken peg mounting and tap hole in base
plate metal to take the nylon bolt.For indexing the mode switch:at
base of helter skelter cam the holes in cogs match holes in the
base plate.
Amstrad UF30 vcr
Failure to accept cassette
The sliding mechanism to lift the flap of the cassette was
floating loose so the lid was not lifting and fouling on the
moveable tape guides.It looks as though originally there
was a torsion spring and locating pin to return the flap-
lift mechanism that had broken and disappeared.
A linear spring seemed a better idea but no room for
a tension spring so fixed a light compression spring between the
sliding mechanism and the fixed part of the cassette handling
housing.Not very elegant as the spring bowed rather than compressed
but it did the job.
Amstrad VCR 4500
Failure to keep tuned channel due to worn /corroded
tuner switch bank contacts. If worth the effort
recondition as per tips file "ganged multiway push switches"
Amstrad VCR 4600
Jammed tape and no transport functions
Wide drive band from the motor drive of the mode
change mechanism had slipped off -excessive
axial play on the spindle of the worm drive cog.
Bent inwards the housing to reduce play,cleaned
belt and baluster pulley on motor and also scored
axial marks with the edge of a file to increase traction
on this pulley.
Amstrad VCR6100 vcr
Coin jammed in cassette carrier mechanism
All sorts of mechanical damage from owners efforts
to extract cassette.Cam train out of sequence and
tape-in positional latitude co-axial split pulleys
either side of carrier had broken retaining plastic lugs,
repair using small nylon spacers split axially and hot-melt
string glued onto plastic cog to allow rotation of the
captive metal disk/arm.
The tape-out/ingress latitude is provided by single
dual pulley adjascent to the worm drive.
Note the 3 limit finger contacts,tape in,tape out and
initiate tape ingress are not all activated in the same
sense from the cam followers.
Baird 8030 vcr
Playing too fast with "Pinky and Perky" sound
The pinch wheel was not engaging. The jockey wheel take off from the
cassette take up spool was jammed into the sliding arm.A circlip holding
this assembly had dropped off allowing the jockey arm to rise and then
settle back in wrong position.
Baird 8947 vcr
Poor rewind
Cracked pulley tyre on supply reel satisfactorily
replaced with circular section 7/8 inch "O" ring.
But main problem not found. Sorting out the transport
and checking there was no video or sound output
only modulated carrier (test signal). Large
crack in main pcb in area around the central plastic
hold down anchor. Repairing them the vcr entered
an illegal mode with capstan running in reverse
and would not power-up from standby. Never found
the fault and abandoned.
ps voltages when removed from vcr
-31,0,0,54
?,?,0,0,?,?, 12,21,.7 There was voltages on
pins 1,2 ,4 and 6 when connected probably gated on by
control voltage on pin 9
ac,ac ,-31,12,0,19
BUSH VCR168 = GOODMANS GVR3400 VCR
Tape jam with tape wrapped around spindle and pinch wheel and large
loop of tape in body of m/c.
In play and FF one of the cogs on the jockey/idler assembly rubbing against
chassis,consequently removing drive from the take-up spool, so removed
jockey assembly and packed out with a thin washer.
Baird VC121 vcr
No REW or FF.
The set/reset mechanism on the main slide bar section of the
mode change mechanism was not going to set condition in retracted
state due to wear on the plastic pivot so shaved off a small slice
of the moving dog that engages with the slide.Thought the spring action
was a bit weak so replaced with a beefier torsion spring but this
led to the mode switch motor stalling and when going into STOP
mode would unlace tape then go ingo REW.So settled with original
spring.After removing the cassette carrier mechanism temporarily
fix the main deck to the chassis before turning upside down the
whole VCR.
Canon E90 camcorder
No viewfinder
C2901 and C2931 panasonic SM electrolytics had failed and
electrolyte had damaged some tracks.Replaced the 47uF,16V and 100uF,6V
with conventional caps. Remade trace between pin2 of IC c555 back
to CN29093 connector and replaced IC protector RR2933.On reassembly the
remaining 3way connectors are line plug and socket to the mike.When
replacing the cover beware of disrupting the 1mm spacing ribbon
cable that lies under the top cover (cover with the R/C window).
Locate this top cover on the deck side side cover and then
slide the viewfinder cover onto this top cover.
de Graaf / Granada V/WHSJS1/A vcr
Transport whine and occasional failure to play
Excessive slip on slip clutch and worn capstan bearing.Cleaned spindle
and introduced graphite powder as temporary fix for whine.
Ferguson 3V57 vcr
Nasty noise from inside.
The cassette loading motor running continuously. The triple
cog assembly had failed due to one of the nylon locators
shearing off and another half broken.The half broken screwed
up from rear with small self tap screw and epoxied in place.
Repeated same with 2 still good pegs. The failed peg used a
bolt epoxied in place with head ground down partially so
as not to interfere with the intermediate cog. There are
index dimples on the cogs to align on reassembly.
Ferguson FV21R = JVC HRD400
Poor FF and then tape jam.
Distorted spring and graphite laden disc inside
the idler assembly ,while awaiting a replacement idler
tried reassembling with the spring replaced with a disc
of squashable rubber 0.2mm thick and all transport
functions worked ,whether long-term solution,not known.
Fergusson FV21R
Intermittent tape transport failures.
The idler assembly was riding high and interfering with the surround to the
drive motor spindle. Also the aluminium hoop that retains the spring
that holds the idler in contact with the motor spindle was just high enough
to sometimes touch the bottom of a cassette
Ferguson FV21
Manual record and short lead-time timed record OK but failure
of overnight record.
Replaced the the 3 small electrolytics on the clock / timer panel
and broke / inspected /remade all connections and
also at someone's suggestion tightened all earthing point through-pcb
screws on the various boards.Somewhere along the line must have
effected a cure.
Ferguson FV21= JVC HRD170 to 330 vcr
Jammed mode switch actuator arm.
The jockey-wheel assembly was jammed against the 2 steel
pins of the actuator arm,access via removing the two motor mounting
screws.For alignment of the mode switch the 2 V-shaped notches in
the body of the switch are aligned when the m/c is in neutral
with no motors active.
Ferguson FV21R VCR
A few mis-tracking lines at bottom of image
Dirty and compressed felt on the tension arm
copper/felt belt wrapped around supply reel.
Mark the position of the fixed anchor and then undo to release
the band.Clean the felt with methylated spirits and slightly
roughen the felt and replace.More permanent replace the felt
(from haberdashers).Pare off the existing felt and glue (as in
hints/tips gluing plastic) a new strip and razor back the excess felt to the
copper band..Refit and adjust for correct back tension.
Fisher FVH-P710 vcr
Poor FF and REW,squeel on mode change,eventually jammed tape.
Stretched band leading to FF and REW problem.Stretched band on mode
switch assembly leading to remaining problem.
Fisher FVH P906
No tape functions.
Original fault was excessive slip in the slip clutch under the supply
spool but someone had tinkered in area of 2 locus cams.There was greased
track in the smaller of these cams but no locus follower assembly.
There is a long pivoted arm that engages with the large locus cam but needs
another linkage to activate in FF and REW.There is a return spring to
this arm but introducing another stronger spring pulling in opposite sense cured this
problem.What the original mechanism was I have no idea.
GEC V4006 VCR (1986)
Tape stuck in machine.
Goes into safe mode if timed-out the mode change
from tape in to tape play. Due to gooey grease on
the worm gear of the mode change motor.
Spun up with brush loaded with meths to
clear away grease,then silicone greased. I think
the motor could do with more voltage in this last
sequence - it should not need grease on this cog IMO.
Goodmans GVR3400
Dead m/c
Loose wires in mains plug had led to 400mA internal
mains fuse blowing
Goodmans TX1200 vcr
Low sound for self record ,normal level replay from pre-recorded tape.
Traced the audio component feed back from the audio head,as distinct from the bias oscillator feed
which was fine 30V or so. In the audio trace near the bias adj. and osc. transformer
there is a 22K sm in line so paralled a 13K sm with this to raise the level on record
Goodmans VCR 2000
No mechanical functions.
The main deck spindle driving the jockey wheel assembly had deformed
sufficiently to break contact with the driven pulley bottomed out
against the arc slideway in the chassis. To get to this larger pulley
remove the take-up spool and disengage the torsion spring retaining it
under the chassis. To access the small pulley - remove the belt drive pulley
under the deck. Remove the cassette carrier assembly and 2 screws holding
the spidle housing for this drive assembly. Could not find a replacement
barrel type pulley tyre so removed and packed out to take up slack - a
bit lumpy-bumpy but hopefully would bed down rather than get more noisy in
use.
Godmans VN9500S, 2000
No functions, showing Err on display
On loading the mode select gearing does not stop at selected mode
and continues to the end stop.
Dismantled the mode switch and reconditioned as per pots.
Index marks on green and blue sections of mode switch
are adjascent for tape out position.
Mode switch connections at connector
Tape out , D-Gnd
Full FF, not half cock, B-Gnd and B-E
Play , E-Gnd
Granada YH2 vcr
Only forward,no rewind or play,no response at all eg motors etc.
Dry joint on the signal conditioning circuit for the supply-side
end of tape sensor.
Grundig VS 520GB vcr
Jammed cassette carrier
This is the same tape deck as used on many Panasonic models
with the helter-skelter cam for moving the pinch wheel. On the
main drive side of the cassette carrier the two part lever
mechanism (that through connects to similar mechanism on left side)
had bent so allowing the driven pin to disengage.
Beefed-up the lower of the two levers with a piece of metal strip
hot-melt glued in.Clamp the lever of interest against the body of
the cassette sub-housing.Gradually (to avoid any more distortion)
melt the glue into the recesses and pre-heat the metal strip to bed
into this now cooled glue.
Grundig VS520 vcr
Lock-out from the system-no tape functions
To unlock the code-lock: Open the vcr and find the testpoints on the display`s
pcb. This is usually 2 pins near the upper edge near the keypad,near the 0 keypad.
Connect the vcr to the power-line, short the test-pins together and press `stop`.
Setting the head-switching pulse: Insert a real prerecorded cassette and
short the testpins. Press `6` on
the keyboard. The vcr will now align the switching-pulse. If successful `A6` in
display disappears and
0 appears. To exit the service-program, press eject or stop.
To reset a timer alternately press the timer button that flashes and `0` until it stops
flashing.
Hitachi VT 35E 1984
No tuner and poor FWD & REW
Hank of wires going to tuner were draped over the top edge of power
supply board. With owner putting stuff on top of machine meant one
and half wires had been severed. Transport functions returned
changing belts
Hitachi VT 64E
Erratic tape speed.
Worn out capstan motor,swapped with the similar looking
motor from an Akai VS4 but ran too slow presumably by
a factor of 7/12 ,had to swap the 48 pole tacho
with the original 28 pole tacho.The tacho housing
is just pip-swaged / welted to the body so easy to
prize off.
Hitachi VT220E vcr
Gradual fading of colour and intermittant loss of colour
Dry joint on the SAW filter also bad solder joint of a SMD
chip mounted on the stand-off sub-board located near this
SAW filter,unknown identity as coated in black epoxy paint.
Also for good measure the tape transport would have
soon failed due to compressed / perished pinch-wheel.
Hitachi VT 430E
Intermittent failure to play, just a judder from the motor then drop out
to safe mode, then later intermittent colour problems eventually intermittent
total loss of colour.
Drive problem associated with black epoxy painted daughter
board on main board near SAW filter.
Colour problem associated with the other such ceramic sub-board
near SAW filter and under tuner sub-board.
Pressing on the main SM chips on each of these boards 'cured'
the problem. Not knowing how to remove epoxy paint , stuck
a rubber pad to IC on one and top of crystal on the other and
tightened a couple of small cable ties around and under
each of these ceramic boards.
JVC HR A630 VCR , 1996
No display, no finctions. HV DC at the ps but no oscillation, 5V
at the HV side of the opto-isolator.
I'd removed both the switching power FET and the biasing driver 2SC3616
because there was a 220K resistor between G and S which was not on the
schematic of JVC HR J725 with similar ps I was looking at and confusing
the cold checking.
I removed the 2uF,50V to the G as well, nothing seemed to be wrong with it
but was intending to replace with 2x 1uF,63V in parallel but accidently put
them in series so only 0.5uF but it worked all the same. I'm not convinced
it was a problem with that electrolytic but its the only thing I actually
changed.
Its RTFM for setting the tuner, also for HR A631
Ch Set/OK/Jog Up/down / Ch Set
For manually resetting
Ch Set/Jog /OK/(number)/OK or Store/repeat/Ch Set
Fine Tune, select ch/OK 3 times/Jog/OK
"Guid" relates to Videoplus
JVC HR A630 VCR
re-use after storage, immediately blew internal mains fuse.
Blown smps 2632 s/c all round,replaced with a IRF740, with insulator and
one of the locator nibs ground off the heatxink plate,
but running hot, so obtained a 2SK2632 replacement .
JVC HR D170 vcr
Poor picture in E-E and play and "test" card
The owner had been using with the TV tuned into a strong
secondary image frequency of the output modulator.In this
m/c there is a 2-sided 3-hole corner brace over the p.s area
which was loose (no designed fixings) and nearly touching
an interboard connector point on the top pcb,also could
have slipped into the p.s. area so bonded this corner brace
to the 3 plastic support lugs.
JVC HRD230 vcr
Intermittant failure to record timed recordings
Replaced the small drive belt that powers the
mode change mechanism.
JVC HR D400 vcr
Warbley sound and switching line in image.
The switching point could not be shifted off screen
by adjusting R430.Fault was poor contact/s? in the
connector CN1 taking drive signals to the deck motors.
JVC HR D400 vcr
Mode switch alignment.
This switch has 3 pins ,the only position where all the pins are s/c
is in the neutral position at the extreme position with the slide bar nearest
the locus cam.There are numerous positions where the 2 outer pins only
are s/c.On the locus cam the neutral (index) position is when the innermost
small hole in the cam aligns with a similar hole in the metal cover.
JVC HRD400
No play mode
Capstan wheel not rotating.Due to failed connection in the
nasty 1.5mm spacing ribbon connector socket on the mechanical
deck.Relieving spring action to release cable ,resetting pin,reintroduce
cable and have disturbed another line.Redo and this time break one of the
leads.Sod this for a lark.Desoldered the socket after cutting away some of the
plastic of the chasis.Soldered the ribbon to the top side of this socket,beefed up
with hot melt glue and soldered back in place.
JVC HR D560 vcr
No picture
Both video heads were dirty so cleaned (power off)
with stamp-sized piece of clean copier paper.
For thicker accretions dampen paper with methylated spirit.The trouble
was probably due to the flimsey foam cylinder on the
auto cleaning arm breaking up.Removed the whole cleaning
arm assembly ,never have liked the snatch loading in the
most sensitive area of a vcr when these arms engage with the
still spinning head drum.
JVC HRD610EK vcr
No control over tape functions,only choice of (play+FF)
or (play+REW).
Lack of freedom for click switches behind front panel
meant FF and REW click switches one was deformed
and the other was intermittently on.Replaced these two
click switches and packed out between pcb and stand-offs
with 2mm spacers.
JVC HR J225 , 1995
Mechanical deck much as HR J725 or HR J825 so applicable there.
Mangled tape due to eratic forward and reverse tape wind.
The cogs not meshing due to wear inside the complex
assembly over the main large drive cog.
No need to remove deck in retrospect.
But for replacing main drive band etc
Undo the 4 ribbons and reinforce the thin one before remaking
2 large screws and 2 nylon pcb standoffs at front.
Remove metal band along rear edge of rear slide bar.
Remove the metal strip between the 2 intermediary double
slip clutch cog drive spindles.
Remove the circlip at the wormdrive cog , but mark
the position , in neutral, just in case and bend the
white slide bar up and rearwards to get at the central
pivot. Beware the spring buried inside, only 50gm to
compress to half length. Replaced it with a stiffer
spring to keep the radial arm jockey assembly from waggling
up and down. Required reinforcing the slideway retaining
claw by gluing to the central IR light guide and
cutting back the corresponding hole in the base
of the cassette carrier to stop it fouling on the light guide
as it bends a bit.
The end of tape sensors also use light guides and the
tape-in switches are below the CC display.
Drop the cog on the end of the swing arm by padding out
with a pair of running washers.
If the top plate , between intermediary slip clutches,
fails to locate properly , check whether you've
doislodged the fiddly black swinging ratched that engaged with
the supply spool. Unplug the ribbon to the function select
motor before powering with 9V battery , in either direction,
to check for any jams/ slippages with both slidebars etc.
The cassette carrier is easy to remove/reassemble if
in neutral position and tape out, just 4 screws, no
wires or index marks to observe.
JVC HR S5000
Jammed tape with small motor spin noise.
Stretched mode switch belt.
With m/c powered on manually assist the driven side of the
mode switch until the cassette ejects.Check there is no movement
of mode switch between powering on and off on the front switch.Mark the
positions of the cogs on the mode switch gear train.
To replace belt.Desolder the ribbon cable,remove mode sw cover screws,pull
away leaving the through chassis linkage in place.Remove plastic
circlip on end of spiral cog and bend out end housing.Change belt and
reassemble and
reposition train to marked position.Reassemble the mode switch while pushing
the rack part of the mechanism to position in direction of mode sw.
P.S. voltages in stop mode on 9 pin conector.
1 -36V,2 54V,3 0,4 7.8V,5,6 0,7 17.7V,8 0,9 15.7V
JVC Nicam stereo (model not noted)
Non ingress / egress of tape because corner
of vcr housing is damaged by a knock.
This repair is probably valid to most vcrs with
plastic actuator triggering the cassette entry flap.
The knock had broken off the small spigot that touches
the flap.Cut off a small piece of right angled aluminium
heatsink and abraid off the surface to be bonded
to the remaining part of the plastic actuator.Hold with
pliers and heat with a hot air gun to melt hot-melt glue
to give a good bond to metal.Pretreat the plastic surface
to be bonded (see hot-melt string in tips).When ready to
bond then heat with soldering iron both parts and hold
together till bonded then reinforce bit by bit around
the join.
Matsui VP 9031 vcr
Lack of colour on off-air signals
Something wrong with the tuner ,owner accepted "cure" of plugging in a UHF
aerial booster
Matsui VP9301
Fails to play
Too slippy slip-clutch.
Remove plastic circlip from underside, assembly is
sprung. Separate both halves by placing a blade
in central section containing 2 concentric springs.
Clean and slightly roughen.
Matsui VP9301
No functions followed by shut down and no
tape eject. Loop of tape in m/c.
Seemed to be problem with mode switch or
tape out sw but not so ( action is through deck and push sw on the
main pcb. Capstan spindle rotates
but not the slip clutch. On removing the base cover
a small piece of black plastic was loose and the drive belt.
Plastic split radially and dropped off the end of the capstan
spindle. Glued back in place ignoring the split.
Matsui VP9301
Switches off after a few seconds and no functions
with tape stuck inside.
Push the sliding part rearwards on the carriage drive rod
and turn the bit with the 2 fins to manually lift out
the cassette.
A bit of gummed label stuck to the hole uinder the
cassette interferring with the IR LED post.
Poor jerky play/record towards the end of the tape
furthest from the start end, also poor wind
when most back torque on the tape spools.
Lightly oiled on the capstan spindle bearing.
With test tape in and exposed tape spool.
20 to 30 gm at 38mm radius hole on the spool
corresponding to 18 to 22 gm at the slip clutch.
Upped to 50gm at radius 45mm on the slip clutch
pulley by packing out with matchbox and rubber
band and turning by hand. Gave too much torque to
measure on the test cassette spool.
Changing the main drive band to a larger
cross section and tighter one led to failure
of play function due to misaligned capstan spindle.
Matsui VP9301
Nasty noise , no functions and switches off after 5 seconds or so.
Broken mode switch motor band.
On replacing the belt, B&W picture and multiple
interference bands.
Due to something mispositioned after trying to
manually drive the gear system to eject the tape
stuck inside when the band broke.
Matsui VX1100 vcr
Intermittantly fails to play or REC.
Could not induce the problem myself.
The slip clutch assembly had obviously been rubbing an
arc on the take-up side of the deck. Removed the slip-clutch
arm and packed underneath with a thin plastic disk. Cut back
the small proud ring on the top of the arm to relocate the plastic
circlip.
Matsui VX820 vcr
FF and REW but no play also intermittent non eject
Once again that cross-linking pin that moves the take-up
tape guide into play position had dropped into bottom of
machine due to cracked plastic so tape guide contacts
the pinchwheel.Replace the pin with a longish(for a 8BA bolt)
the correct length and beef up the plastic with hot-melt glue
and cut back a bit of the take-up spool brake so it does
not foul on the beefed-up linkage.The intermittent failure to
eject was due to the owner placing TV immediately on the
vcr and deflection via the small rubber block on the right
hand side of cassette handling mechanism and distorting
the housing.Also rattly squeal from the anti-static
conductor rubbing on the head rotor spindle was cured
(short-term?) by a very small dab of silicon grease.
Matsui VX880 vcr
Loud rattling noise in FF and REW
From underside remove the complex slip clutch assembley
that drives the jockey-wheel .Pack out on the
end next to the plastic ciclip with a small graphite loaded
plastic running washer to take up the wear.
Matsui VX880 vcr
Intermittant failure during play
Cracked pinch wheel surface
Matsui VX1108, 2000
Jammed tape, for no known reason
The nearby phototransistor survived me putting
9V across it both ways, thinking I was feeding the
load/unload motor, thinking the wires went to the motor.
Removed and reseated leads and plugs/sockets-under and no further problem , so
perhaps just that.
ps 82K,220,1R8 and LV side 22,220,1R
Osaki VCR 34H
Intermittant no REW or FF
Originally thought to be slip clutch problem.
To get to remove cassette housing and rubber drive band
underneath - to assist reassembly cut away the plastic chassis
around the bottom pulley driving cassette carrier.
Remove large bottom pulley from the slip clutch assembly.
Long armed intermediary double pulley assembly is on
the right and is engaged in neutral, both arcing leftwards
for REW or FF. Small sliding bar interfering with the right
hand brake should be fully retracted in neutral.
Double slip clutch assembly order of assembly
Small black cog, spring, steel disc,white cog,
large black cog.
End of left steel slide bar goes under the end of the
long armed arcing dual pulley assembley.
Trouble became apparent only when operating with
the cassette carrier removed but ribbon cable connected.
The doubled up sliding white slide bars have a trigger on
right end that is delatched when kicked by the "star" cog spinning up.
On top of this double white slide bar is a latch that sometimes
stopped angled rather than inline and needed the return torsion spring
increasing the torsion.
Osaki VCR 34H
Fails to eject etc, dropping into some undefined state.
Repeated pressing power on/off would eventually
cause a click of a latch and then normal functions.
Failing belt to the second largest of the 4
pulleys underneath.
Osaki VCR 34H
Replaced pinch wheel with one 1mm greater diameter,
as slipping, tape damage.
Osaki VCR 34H
VCR works fine in play and record as long as the head drum gets up to speed
by flicking by finger while the tape is lacing.
So assuming nothing wrong with the bearing , normal free movement when
unpowered.
Sometimes drops out in play or record on hitting ruffled tape so a motor
problem.
3 lines from the TA2620D driver IC to the coils and further ends of each
are joined together but not returned to anywhere so presumably 3 phase.
There are 12 coils from these 3 lines mounted on the iron frame with 12
'poles'
The surrounding magnet rotor part has 8 North poles, 8 South poles.
On pcb 3 hall effect sensors presumably for relative phase monitoring these
magnets and a separate magnet pip on the outside of
the rotor and 1 hall effect sensor for 1 pulse per rev.
But what is the PCB track/coil ? etched on the board under the rotor.
Not connected to anything else on the motor sub-board and just copper track
as far as I can see,
roughly like Beta vcr tape path, one track runs right round circularly and
returns 'circularly' with 24 castellations pattern.
What and how is it sensing or sending anything? and what's its function ?
I tried another matching salvaged multimagnet rotor and can eliminate
magnetisation loss as reason.
The castellated track seems to supply a tacho signal. The off "main beam"
multipole magnets on rotating must be flux cut by the castellations inducing
a low level signal. May feed a drum loading/cut out as well/instead of
monitoring drum motor current - i don't know, not followed path.
Main problem seemed to be ps problem. Caps ok.
Decided to uprate .1A biasing Tr (2SC1740) to .2A BC449 swapped legs, and pass
Tr from 3A to 6A TIP41C and
changing 13.6V setting zener (marked C12) to 15V to see what happened. Much better start
up torque, checking Vs I'd put a 13V Zener in by mistake
and drive volts was less at 11.5V down from 12V. Replaced with intended 15 V
and drive V then 13.6V but very little torque.
Returned to 13V zener and no problems since, caters with rinkled tape now
without cutting out, i doubt its a permanent cure though - weird.
The zener on the drum driver board seems to be 2.1V, i changed it to 2.5V
and the whole drum drive ceased, changing it tp 1.5V zener the drum speed up
was good and cync-lock was good but stayed on permanently and left it
in this situation. VR132 changes rotational cync point of drum .
Cutting the line to the 24 "castellation" track meant no cync-lock with the drum running up
to maximum revs, so speed feedback to drum servo cct.
Excluding microswitch lines the lines to this drum driver board are
(before altering so maybe wrong)
0,12,2,2.4,2.4,0,1
Panasonic NV D80 vcr smps problem
Failure to start up.
After removing the power unit and checking this and that
but not actually replacing anything then refitting in the chassis
the m/c would work a couple of times then fail to start,never
starting again until repeating the same abortive procedure.
There was some sort of "memory"
effect going on.
The 47uf,63V electrolytic was leaky on the supply side daughter board,
On removal this cap showed 5micro-amp leakage on 9V and
on an ac capacitance meter showed about 2microfarad.
Panasonic NV D80 vcr.
Non ingress of cassette.
Large toothed pulley driven by toothed belt had
fallen off spindle as retaining circlip had failed.
For the archives the power supply voltages should be
1 Gnd,2 Gnd,3 Reg 5.1V,4 Reg 6V,5 12.3V,6 power off 'L' ,7 Unreg 14V,
8 Reg 45V, 9 Motor Gnd, 10 Reg -30V, 11 Heater +,12 Heater - ,13 non-sw 12V,
14 LED Gnd, 15 Unreg 8V.
Also in p.s. R08 and R35 should be 0.39 ohm.
Panasonic NV D80 vcr
Tuner memory failure
After an hour or so of m/c being powered up,on
changing channel the tuning voltage would be at top
of range (32v) and m/c useless until cold again.
Squirting freezer spray on the EEprom MN1220
under the display bezel restored function again (temporarily).
As could not find a DIP version of the MN1220
put a zener in the line to pin 9 of the IC to
drop the voltage from a bit to cure the temp
build up and restore normal function read and
write .Also formed a
ventillation hole in body under this area.
Panasonic NV D80.
No functions.
Behind the front panel the eject button had partially
sheared and jammed the click switch in active
position.Also the memory capacitor had failed,to
avoid total dissassembly of the innards,desoldered
the errant cap in situ and allowed to drop out and
replaced with a new cap mounted off the board wired to the
original site.
Panasonic NVJ35B VCR
No tape igress or other mechanical functions
The owner had forcibly removed jammed tape and had made the mechanical gear
trains jump teeth and go out of sequence.Turning the large pulley manually
along with manually triggering the solenoid mechanism with the inner right
part of the cassette housing unscrewed and raised to disengage the metal
rack drive allowed resequencing.
Coincidence of both radial tape guide arms in extended position at end of
drive sequence coinciding with cassette in down and locked position
Panasonic NV L25 vcr
Broken cassette carrier mechanism (heavy handed kid)
The 2 flimsey restraint/guide pieces of plastic that hold the
two sliding metal actuators had sheared.For alignment
concerning engagement of quadrant gear on the cassette
hold-in mechanism the last notch of the metal rack engages
with the second to last tooth of this quadrant cog.As far as i
can see the hook like mechanism that latches the cassette-
in mechanism down to the deck is only for assembly .
Find the neutral position of the main drive pulley system by
rotating by finger the large drive pulley and operating
the solenoid or the connected pin on the underside.
Latch the carrier in the down position to reassemble inside the
chassis (with no cassette-defeat the protections) then with
a small screwdriver from the top de-latch this hook.
The steel drive cog that engages with the cassette carrier rack when at
the cassette-in position the index notch should be furthest from
centre of machine.
One of the 2 broken guides needs to be replaced with metal ,
hooked through the body of the carrier housing.Metal about 1mmx15mmx5mm
shaped as half a fylfot/gammadion cross (that foxed you)-
shaped like a riser and tread and riser in section of a staircase
and glued in.The other larger piece can be satisfactorily bodged
with a piece of scrap plastic hot melt glued to shear point
and part of the carrier housing but avoid interfering with the end of tape
sensor.
Unfortunately the whole gear assembley (about 27 cogs) had jumped teeth due to
the plate that holds the capstan-flywheel brake and toothed belt tensioner
had probably stretched between the anchor points of the spindles for the
main mode-change locus-cam and the spindle of the sun and planet assembly.
With a couple of pliers bend top and bottom at the joggle in this plate to
reduce the separation of the anchor points.
For realignment of the 4 separate gear trains from the main drive.
1 Sliding tape guide pins.With tape retracted into cassette the 2 index holes
in the L and R drive cogs shold be adjascent and the hole in the
steel quadrant drive also at point nearest the cog.
2 Main drive leading to the mode switch.
Remove the cassette carrier but retain ribbon connection and
set the carrier in the cassette-in position.
On power up the m/c should settle into the neutral position
with the radial guide arm extended.With the power off with finger
in the large belt drive pulley turn back so the cassette carrier
metal cog rotates back to the cassette-in position.
Continue rotating back the main drive and trigger the solenoid twice
should bring the gear train to the neutral position.
On the mode switch there are two small pegs the smaller should be opposite the
dimple next to the double V on the static part of the switch.This small peg lies
over the switch contact.When all is up and running properly the small pin hole in
the mode switch cog should lie opposite the similar hole in the helter-skelter
cam in the m/c neutral position at 6 o'clock position.
If the m/c ,front panel towards you, then there are 5 connections
to the mode switch 1...5 with pin 5 at 12 o'clock position of mode switch.
Then index position is just after 3 o'clock.
Pin 2 is the common .The index position is the same after power-up
initializing and REW and FF and STOP tape functions.
Play position of mode switch is about 10 o'clock.
Concerning the pinch wheel assembly.
Set m/c in position just prior to cassette eject.The small hole in the mode switch cog
opposite the index mark is the point
of most retraction of radial tape guide.Reassemble helter-skelter
cam to match this position.Add the bobbin sub-assembly and the top double anchor.
For adjusting relative position of mode switch cog it is only
necessary to remove the top anchor and bobbin assembly and move
the helter skelter upwards after depressing the paul locking on the spindle.
If the m/c seems temperamental re gear alignment but is nearly fuctioning
sometimes then with torsional finger pressure on the mode switch cog
try forcing clockwise or anticlockwise and if remaining faults
disappear then move the mode switch cog around one tooth.
3 The pin connecting the larger radial tape guide arm and the cog system had
sheared.This arm onlly moves between initial tape-in and the m/c netral
postion and m/c worked satisfactoraly permanently set in retracted position.
It probably avoids a partial slack tape when retracting back into cassette.
For the archives p.s. voltages 1to12 with m/c powered up in neutral are:-
43,12.3,13.4,15.9,12.2,0,5.4,5.1,0,-28.8,-18.2,-22
The mechanical deck described above is the same as used in Grundig VS 520
Panasonic NV SD200 VCR
Jammed tape and noise like slipping belt on mode switch run-away drive despite no
slippable bands in this type of deck.
First problem the mode switch was stuck in an undefined mode-perhaps
"play" +"rewind" but pinch-wheel disengaged.Powering on and off
would not help and to remove the mechanical deck from the m/c it
is necessary to remove one fixing screw under the cassette.To remove
cassette disengage hold-down arms and springs that engage with pegs
protruding from each side of cassette carrier.Then unloop tape from
guides to give enough slack tape to remove the cassette (tape still
trapped behind pinch-wheel).To remove mode switch remove one screw and
a plastic push-fit stand-off released from cassette side.
The original problem is the nasty piece of 8x4mm plastic on the mode switch
motor spindle.This in turn engages with the worm-wheel with axial latitude
to avoid jamming that is possible with high back-torque worm-drives and had split.
There is not enough material to try gluing and reinforcing so engineered a
replacement fashioned from a piece of brass rod of right diameter and ground down
with a Dremmel and ball-mill to give 2 prongs .Drill to motor spindle diameter and
solder to this spindle by pre-heating with hot-air gun and then soldering.
Power supply voltages:-
1,2 AC?,
3,4 0V,
5 -31V,
6 -17V,
7 -22V,
8 0V,
9 5.7V,
10,11 0V,
12 40V,
13 15V,
14 0V,
15 12.8V
Pye DV105 VCR
One head working other leading to vertical blind noise and distorted sound.
Unclipped the "head cleaner" arm and junked.
Manually cleaned with a piece of paper,power off. Replace torx cabinet screws
with ordinary self-taps
SAISHO VH1200 VCR
No tape transport
Radial tape-guide arm on take up side was jammed
against pinch wheel due to stel pin that
connects to cam system having dropped into
base of m/c due to retaining plastic having cracked
Saisho VR 1000
Intermittant failure to retract tape into cassette on stop.
Replaced the spring that holds the jockey-wheel against the spool drive
motor spindle with a stronger spring. It also cured a long term intermittant
squeal while in play/record modes.
Saisho VR1000 vcr
Moire fringing on picture.
The earthing spring connector was failing to make contact
with the bottom enclosure plate.
Saisho VR1000 vcr
Loud squeel from m/c.
The owner cured temporarily by propping up the m/c then moving to
a different position when it started again. Due to out of parallel between
axis of pinchwheel and capstan spindle.
Saisho VR 1000 vcr
Play function drops out after 6 seconds.
FF and REW ok,play ok for the 6 seconds then tape stops and retracts.
Dirt in the rotation sensor of the take-up spool so falsely registering
as lack of rotation.
Saisho VR1200HQ vcr
No system functions
Replace the power trannie next to the STK5332
with an uprated device (if TO220 then insulate
from the STK regulator.
Saisho VR3300X vcr
Intermittant pause of tape transport
I thought binding of the capstan drive spindle had caused
loading of the 3 phase driver chip M51782..Cooling the chip with freezer
spray temporarily cleared the fault.To remove this heavily
heatsinked IC melt solder around central IC tabs and with a small screwdriver
between IC and heatsink remove the aluminium then prize up the tabs then desolder
as a normal IC.Unfortunately the same fault emerged;it was in fact worn
bearing on the capstan spindle causing the trouble so replaced this and all fine.
Curiously on REW and FF the spindle must have centred itself with no loading
of the IC,only running hot in play (low speed).
Samsung NI 14N3, 2004,Combination TV,VCR, single tuner
Requiring frequent head cleaning because of noisy
picture despite less than 1 year old.
Noisy replay on this machine good played on another machine.
Lot of fine talc-like powder in the VCR section but the
TV section almost spotless. Blew out unit.
Is this another supposed head cleaner gizmo?
Next to the supply side tape guide, on the curved-slotted
pathway, is a brass cylinder that touches the active
side of the tape , rotating with its motion.
I removed it, assuming it is some idea of a duff tape cleaner.
I tend to always remove those nasty foam supposed
head cleaners, on placcy arms that engage with the spinning heads ,
as seem to CAUSE dirty heads. To remove just unscrew one edge
of the screen between TV and VCR it is not positively held
on the pin.
I've never seen one of these gizmos in any VCR.
It is engaged with the tape in all modes,
Play, Play+FF,Play + REW, FF,REW,Express FF & Express REW.
There was a black smudge on this cylinder thingy before I
removed it. Don't know what it was ,didn't blow off or
lift off with a magnet. Probably something vaguely greasy
that came off by wiping with finger.
Since removing this brass cylinder and playing/recording on
different tapes the noisy picture has not returned - so far anyway.
On first receiving and running first time of rec then play
was a good picture, second R+P then noisy picture.
Removed this gizmo and repeated 12 times on 6 different tapes
and no return so far.
Black smudge was something like the way photocopier toner sticks
to surfaces because of the slight surfactant/silicone content. I've never
seen such a smudge on impedance rollers before so can only
assume happened because brass rather than plastic.
Ribbon connector dc voltages going to VCR section in play mode
3.4,0.1,0.7,3.7,0,14,12,9,5.2,5.2,3.6,0,5.2,33
and 1.1,0.5,0,0,0.4,0.4
Samsung SI7220 vcr
Poor rewind
Excessive braking on the take-up reel
Samsung SI 7220 VCR
Reported intermittent loss of picture (to black level) and sound
to mute not noise,on trying also on E-E.
The tuner seemed rather warm,so removed cover and on
digital probing (prodding with my fingers) the TD 6358N
would appear to have had a dry joint.Removed tuner,re-did
all nearby solder joints and left the cover off the tuner
(no ill effects) in case of thermal induced fault.
Samsung SI 7220 vcr
No transport functions but motor noise.
Usual old slipping belt on the mode change
mechanism drive motor pulley.The point of
mentioning is that it is possible to remove old
belt,clean pulleys and replace new belt through
the bottom access without taking the deck apart.
There is just clearance around the mode mechanism to
stretch the belt and pull through the gap.
Use a small S hook (like a shepherds crook),using the
outermost bend to hold the belt while looping onto
the recessed motor pulley.
Samsung SV 627B vcr
Intermittently running slow but never dropping out.
Never occured with me checking it. Inside was a label
floating around under the deck unstuck from a cassette and I replaced the
pinch wheel as glossy. Machine didn't return from owner.
Renoving ribbon cables to heads ,wrap cloth tape strips
around ends before re-remaking connections to beef up.
If removing deck make sure 2 idents are lined up on mode switch
on pcb and 2 idents on cross slide rack under the deck before reassembly. Remove front
panel to get glimpse under deck when reassembling to align
these 2 sections together then mate the connectors at the rear of the deck.
If no spool drive on reassembly then probably these 2 mode sw sections
not mating.
Some DC voltages on m/c in neutral.
Measured on large inductors L401 5V,801 12V,802 5V,603 12V
Samsung VI 730 VCR
No sound on record but plays prerecorded tapes
No trace of bias oscillation at record head or the full-erase head.The bias
oscillator is housed totally in the
can that is the size of a dual IF can,the 2SC1318
in this assembly was duff.
Samsung VX972 video cassette player ,12V
Slipping belt on mode switch drive.
Another of those situations where just a couple of
mm cut in the chassis the belt could be changed without
taking to pieces. Remove the 5 large screws to release the whole
mechanical deck. Mark all cogs and levers of the mode switch
mechanism before taking apart. On reassembly make
sure the back tension brake radial arm is on the correct
side of the trailing tape guide traveller.
Sanyo VHR3100 VCR
Poor and absent rewind
Replace the tyre on the final drive pulley (surface breaking down) on the jockey
assembly or remove,turn inside out and replace.Notes: the earthing straps
to the ground in area of head drum and cassette carriage are necessary or the
m/c will stay in standby mode.Also beware of broken tracks/contacts
on the head drom motor driver board because of proximity to flimsy deflectable baseplate
to the m/c giving intermittent drum rotation and play cessation and unlacing.
Sharp VC 651 is much like vcr Philips VR 6542
except for front panel+ tuner and the rear panel.
Sharp VC 8381H VCR
Failure to fully eject the cassette
Positional latitude for cassette-in is provided by
the springs mounted inside the dual concentric large cogs either side of the cassette
carriage,similar latitude for cassette-ejected is provided by the smaller dual
concentric cog assembly on the left near the motor.Replace one of the missing a
nchors on the cog with a metal pin bonded in and find and/or replace the spring
Sharp VC A502 vcr
Tape jam
Idler tyre breaking up and pulley on shaft of mode switch
motor spindle loose.Dismount motor by removing whole
deck section and deforming the spindle with mole-grips
(lock-jaw pliers) or double-action pincers to give purchase on the plastic pulley.
The ribbon cable to the cassette carrier is disconnected by
pushing on the socket housing.
Sharp VC-D805H VCR
Erratic drum and capstan lock followed by tape
retraction.
Poor contact in one of the connectors on the ribbon
connecting the capstan driver board to the drum driver
board.
Sharp VC MH711 vcr
For tracking adjustment press up or down channel
or both together to engage auto tracking.
Super fast REW or FF on VCR, problem, Sharp VC MH711
Will rewind 90 percent of a 4 hour tape in 40 seconds or so and 20s for the
remainder.
What would allow the motor to run at full tilt ? clunking loudly to a stop.
If it was not for the "crumple zone" of tape pulled into the gap between
tape roll and spool disc then the tape would have snapped at the end of
tape.
What to look for in the way of a problem ?
System presumably monitors ratio of supply and take up rotation rate and
direction of wind and unlaces tape from drum and over 3 stepped increases ,
sets at maximum revs until the ratio goes over a preset value and drops by
stages to a slow rate until end of tape sensor acts.
It should recognize getting close to the end of tape and start reducing the
power / revs of the motor but it once continued at full revs to the end of
tape. Been monitored by human since it happened. It does not speed up if
human stops the motor close to end, goes normal speed to the normal clear
tape auto stop if REW is engaged again ofter pre-emptive stop.
I'm thinking a break in the line from the fast , take up spool sensor, so
less pulses coming from it and false interpretation.
Taking the cover off and visually monitoring the amount of tape left, the
VCR works fine FF or REW . Going up to express rate and back down , in
either direction, as long as there is plenty of tape run..
It just once , so far, spectacularly failed.
Left as is with human monitoring. Owner always rewinds and
then FF 2 seconds to avoid normal tape problems.
If the auto-rev-reduction fails then the ruffled
tape going around the cassette guides will slow it anyway.
Easy to undo the 5 screws, take tohe cassette top off
and unwrap the crumpled tape.
Sharp VCT310 vcr
Jammed tape.
Disrupted gear train,the cam follower pin had jumped for the mechanism that drives
the radial arm that pivots under the audio head. Bad design on the back tension arm
side. With wear of the felt on the brake this arm can rotate beyond the point where
the tape guide on the left hand slide arc intercepts this arm when in tape retract mode.
The slide being worn could also be to blame but either way the two can jam together
and then the cam follower jumped. Unscrew the bolt holding the upper and lower parts of
the slide guide post and fix a modified solder tag to extend the interception surface
and another modified solder tag screwed to a convenient hole in the base pannel to
stop the back tension arm moving too far leftwards. Properly set gear trains and levers
are in stop mode:
Drum lead in / out slide guides notch and peg coincident and small hole and small
arrow coincident.
Small hole in triangular portion of locus cam coincident with a small hole in
the chassis.
In cassette ejected mode the radial arm cam follower should be in the outer slot and
when in cassette-in (stop) mode should be in inner slot.
PS DC voltages on 10 way connector 12,0,9.5,4.7,49,AC,0,-25,-25,0
Sony SLV 715 vcr
Tape jamming on take-up side.
The pivot of the take-up side radial arm tape-guide was sticking so
would not retract with the actuator cam.The lubricant between
gudgeon and pin had deteriorated.Disassemble and clean pin and
"ream out" the gudgeon with a wooden matchstick and reassemble
dry.
Sony SLV 715 vcr
No functions ,no response to on/standby switch.
No 12V rail ,in the ps the supply to the IC203 regulator
had a poor joint.
Sony SLV 715UB vcr.
No front panel display
There was no -30V (printed on pcb as 30V)or luminescent display heater
voltage.In the ps C203 1500uF,25V had leaked electrolyte
which had corroded /charred a hole through the pcb in an
area with no components,between traces for the positive side
of this cap and one of the display heater lines in the area
(but not involving)C214.The electrolyte had continued its
destruction on the track side of the board,20mm of one trace had electrochemically disappeared.
Made good all tracks,clean all surfaces of electrolyte
an abraided away the charring with a dremel (charred pcb resin material is conductive)
,replaced the C203 cap and an open circuit R202 150 ohm,.5W of the
-30V rail.
For the archives CN412 power rails should be
1 GND,2 Unsw 5.8V,3 -30V,4 heater 0,5 heater 3.2V,6 nc,7 power on,
8 Gnd,9 12V motor,10 12V motor
Telefunken 1950 VCR
Tape jam,no transport or eject
Worn brush fingers in the lacing motor
leading to short and knocking out 1.5 Amp
pcb fuse marked F15A that feeds the M54544
motor drivers
Toshiba V83B
REW but not reliable Play or FF
Slip clutch problem. Remove cassette carrier. Prize off the top
cap on the spindle of the slip clutch after disconnecting the hold on spring
carefully not to let the "clutch -plate " spring go flying. Replace the pulley
tyre ,stretch this clutch plate spring a bit and before fitting the other spring
reduce its length a bit.
ps DC voltages from transformer end
19,.7 // 9,0,12 // 9,NC,11.7,0,13.5,0,12,2.8 // 11,-21,-21,0,0,3.9,1.8,-60
Toshiba V631 VCR, 1999
Would play pre-recorded tapes only - very snowy picture.
Comet tails on picture noise and 2 of the 4 heads were
chipped in central gap section.
Would only play as AUTO with record switch open from
cassette ingress otherwise no deck
functions - no play,REW,FF or stop or eject. Stop engaged
by pressing REC and eject by pressing Standby.
Central source ,End and Start sensors OK and
3 contacts of mode switch seemed ok. Didn't proceed
any further
Toshiba V703B VCR
Modulator has no UHF o/p including test "card"
Heavy handed adjustment of the UHF channel change had
broken the retaining clip for the moving vane spindle of the
tuning capacitor allowing MB to short to earth knocking
out the "TO-92" packaged pcb fuse Z681 marked N5 ,replaced
with a 500mA fuse.
True tape counters
Beware of apparent non-function of tape counter
where the tape is brand new with no control pulses
recorded on the tape.
VCR and TV tuners with broken co-ax connector plugs
and sockets.
The mechanical strength of the junctions between
these connectors and the tin plate housing of the tuner
get flimsier and flimsier with later models.As the pin on the connector is
usually soldered direct to the tuner/modulator pcb it is
usually impossible to make a good job of reassembling.Remove
the covers to the tuner and strip back some RG178/BU or
similar 3mm coax (to be able to curve around to good fixing pad inside the tuner)and s
older to a good bond point on the pcb.
Find a good earth point for the shield and make sure the cable is well anchored
to the external casing with cable ties etc
and solder on the relevant coax plug or socket to be back
in operation.Often possible to do all this without removing
the tuner /modulator etc from the machine.
Televisions and Monitors
Akai CT2870E TV
Tuner presets
Select preset number
Press C-P
+ or - for channel
Press M briefly twice to store in memory
Akai CT 2870E TV (dead)
Dry joint to the point of being spark erroded to no contact on
one of the pins of the L part of the LC mains filter next to
the mains switch. Wired in and resoldered all similar points.
Soon after repairing the 2A fuse failed probably due to
excessive loading by repeated surge current when the
dry joint was failing.
Akai IRS FX 5652 1323 TV remote control
Intermittant failure to operate until one ofa few
keys in one area were pressed.
Remade the solder thru board solder bridges
in area that 'cured' the problem.
Compaq 420S colour monitor
Intermittent slow fading of image, slowly varying
brightness or failure to bright-up at switch on
until the casing is knocked. Also occassional
sizzle discharge noise accompanied by slight width
reduction and loss of resolution in parts of output.
The slow fade was the give away. Poor solder
joint on CRT connector to back pcb in the heater lines.
PCB holes were too large for the pins, so cut small loose
spirals of tinned copper wire and soldered around pins to pcb pads
on all pins. Also the solder to the 3 colour driver power
trannies looked inadequate.
CTX 1565D Computer Colour Monitor
Black screen but on-lamp ok and yoke crackle on switch on.
Bad solder joints on 5 of the 8 pins between CRT socket
and CRT mounted PCB. The pcb holes for this CRT base socket were
obviously made for batch of sockets with much larger pins so
leaving too large a gap to be
filled with solder. Slid a small brass washer down each of the pins
and bedded into the solder pads. The owner said the monitor had not
been dropped or
the rear pannel pushed or knocked so there is probably a lot of
monitors of this model with this fault. Unsolder the earth straps and the 4 earth
bond point fixings to the pcb to remove the tinplate screening.
Generic TV r/c fault
Total failure of r/c
To mount the ceramic resonators they usually need to have their
legs bent but this stresses the plastic that seals the 2 parts
of the housing and eventually can force the 2 parts apart and the
resonator is no longer held by spring action.
Goodmans 206NS TV
Broken aerial input socket from tripped over trailing lead.
Remove the cover from the DT2 IV17D tuner,not the soldered one as there
are active returns to this cover. The central socket connector was loose but
instead of removing the soldered-in side abraid the small rf coil near the socket
and soler the conductor of a small piece of co-ax. Anchor the cable to the socket
and lead through a fashioned hole in the casing made under the socket hole.
For the records a suitable remote controller for this TV is R28B03.
Panasonic WV51E CCTV camera
No o/p and also loading the monitor supply.
Small dropper to the heater had touched the chassis
shorting the 9V rail and also knocking out the
470uF,35V coupler / de-coupler at the output.Note
the camera needs a frame sync source (to sync all 3 cameras) from the monitor /
supply as well as 12V
Sony KV2216 tv
Inability to tune in stations and erratic functionig of tuner buttons
One of the program buttons was effectively permanent on and replaced
all similar buttons with switches with a positive click action.
UOSD 2000 remote
Intermittant
Battery contacts need re-soldering with wire reinforcement on
the pcb and hot-melt glue filling the gap between the contacts
and the main IC to hold in place.
TV remote (zapper)faults and repairs.
1;resolder battery contacts on PCB and physically
reinforce.
2;IR LED solder joints,sometimes IR LED failure (solder any old
red LED in parallel to check).
3;Broken tracks from being sat on/knelt on
4;failed ceramic resonator,check
by replacing with any old resonator before
aquiring the correct frequency.
5;Gradual failure of the most used buttons-worn
conductive pads-see hints and tips files.
6;Sudden loss of some functions due to break in track in
the keyboard multiplexing.
7;Very rarely is the fault in the main IC.
8;The most common problem is spilt liquid corroding the contacts,
through-board jumpers or pcb tracks.
Saitech 165H (Kasparov) Chess computer
Failure to acknowledge presence of pieces on 2
of the rows.
Liquid had got between the playing surface and the control
pad area where the silver printed signal lines pass through
and corroded the tracks.Hard wire with fine copper
wire between the line area (use silver loaded paint to contact)
and the main pcb.Place tape over the gap to avoid any future
trouble cleaning with an over damp cloth etc.
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,England SO17 2JN
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.
If this email address fails then replace onetel.com with fastmail.fm or
replace onetel.com with divdev.fsnet.co.uk part of the address and
remove the 9 .
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. If you suspect problems emailing me then please try using
my fsnet.co.uk account.
More hints & tips and repair briefs on
homepage http://home.graffiti.net/diverse:graffiti.net/
