Electronics > Repair
Thomson CD player optical pickups TCP11 TK2 squeal
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alan.bain:
I've been repairing a JVC UX-H10 for sentimental reasons (I have many better CD transports). Laser diode o/p was low and it wasn't focussing. Manual described transport as a Thomson TCP11 TK and I was able to source a purported replacement from AliExpress (TCP11TK2L4AM235).
It does sort of work and plays the CD but complete with a horrible high pitched whine (around C7 on the piano so maybe 2kHz - the piano was nearer than the frequency counter). To clarify the whine was not in the audio output but coming from the transport. It's not coming from the motor, so it's clearly a focus/tracking servo problem.
There's no servo gain adjust - servo is built around TA2092 and TC9462F which have limited data sheets which suggest gain is automatic, but a quick inspection of both focus and tracking servo waveforms suggests they are working hard and the TA2092 is getting very warm.
After being on some time, the tracking starts to fail for the inner tracks.
I rather suspect I've got a dubious clone OPU with either a defective photodiode array or poorly aligned optics. But is there any help out there for finding one that actually works? There's more data around on the KSS240A.
shakalnokturn:
I wouldn't be surprised if you had a new defective pickup.
Does the CD spin true enough?
Any chance the CD support is too high or too low on the spindle motor axis? (Which could make sense with losing track only on the inner.)
I'd probably run the new pickup on the old transport or swap the spindle motor just to be sure.
Other than that, have you checked supply rails and electrolytics in the servo section?
alan.bain:
Thanks - tried new pickup on old transport and exactly the same behaviour. CD appears to run true using at least the fingernail test and no dirt on the cd bed or magnetic clamp.
Supply rails looked OK, but 9V power supply regulation (for motors) is somewhat iffy, but that did rather appear to be a "feature" of the original design. 5V regulation good. There is a 220uF in the servo which I should indeed check - thanks.
Alan
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