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.




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




 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.



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


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.

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

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.

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 ?
Are there safety grounds anyway for changing to a 1N4007 or so ?
Single element rectifier
Siemens lazy S logo
Made in Germany
2250c50
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
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.

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.

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

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. 

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 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.

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

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.

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 slippinng.
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.

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" mat.
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.
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 microswith allows
exposed to work on in operation. If 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

 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 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.

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 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 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.

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.

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.

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 KD D30 Cassette tape unit
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. 
Bent back the static leaf and reinforced the outer edge 
with hot-melt string.

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

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.

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.

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

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.

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.

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.

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.
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 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 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.
Also increased the tension on the relevant torsion spring 
that engages this drive.

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.


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 
diverse9@onetel.co.....m ( for anti-spamming reasons 
please remove all 5 dots ..... between co and m ) 
Plain text only (see below) 
 
If this email address fails then 
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/