There is a diagram of a Sony decoder board - and lot's of hints. At least it should be possible to find an original service manual with the Sony circuit...
Yes, as posted up here. I have schematics. The problem is what to look for. There is a failure chapter with detailed instructions (pages of them) about the servo board, but that works.
Nothing about the ‘no sound’ symptom, or the DAC part itself.
Nothing about the ‘no sound’ symptom, or the DAC part itself.
I would check with the scope if data enters the DAC chips and if not where it get's lost upstream by probing the pins of the chips. The datasheets should tell which pins are the ones to check...
Can you see something entering the SOPHI at pin27/28 of CX7933? And can you see something coming out from SOPHI at pin13 of the 74LS166s...?
Can you see something entering the SOPHI at pin27/28 of CX7933? And can you see something coming out from SOPHI at pin13 of the 74LS166s...?
That's the whole circuit, not just a section of it? If so then so much for bypass caps and that sort of thing like we generally see nowadays...
Anyway if all the schematics are present, agree best to start checking signals.
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Datasheet for MSM2128 attached. Just a memory chip.
EDIT: Also a little info on some of the other chips.
EDIT: Also a little info on some of the other chips.
No there’s nothing to see there. Just a peak when I select the next track, or pause, etc.
The Sony module was used before Philips released the SAA7020, which itself fails (I’ve replaced it on two players).
Sorry, I got confused... And what about input/output of SAA7010 if there is such a chip in your player?
“Lorsque UNEC (point (83) est continuellement haut, un des IC DEMOD, ERCO ou la RAM sont fort probablement défectueux.
Lorsque la sortie UNEC fonctionne normalement et il n'y a toujours pas de musique, un des IC CIM, FIL ou DAC est fort probablement defectueux.”
When UNEC is always high, either one of the DEMOD, ERCO or RAM is probably bad.
If UNEC operation is normal, and there’s still no music, then the FIL, CIM or DAC chips can be defective.
UNEC fine and various check points on the ‘scope perfect.
Since the SOPHI version has no CIM, and both 1540 can’t be dead, can they, I think that the M4551 chip is kaput.
Any thoughts?
Lorsque la sortie UNEC fonctionne normalement et il n'y a toujours pas de musique, un des IC CIM, FIL ou DAC est fort probablement defectueux.”
When UNEC is always high, either one of the DEMOD, ERCO or RAM is probably bad.
If UNEC operation is normal, and there’s still no music, then the FIL, CIM or DAC chips can be defective.
UNEC fine and various check points on the ‘scope perfect.
Since the SOPHI version has no CIM, and both 1540 can’t be dead, can they, I think that the M4551 chip is kaput.
Any thoughts?
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Probe the input and output pins of the SAA7010 with your scope (iirc pin7, pin26, pin27). M4551 is SAA7030: can you see something on this IC at pins 3, 10, 17, 20?
Just use the block diagram I posted and probe all in and out pins of the ICs before and after the SOPHI. Do the same with all in and out pins of the chips inside the SOPHI board. You should be able to see where the chain is broken...
Just use the block diagram I posted and probe all in and out pins of the ICs before and after the SOPHI. Do the same with all in and out pins of the chips inside the SOPHI board. You should be able to see where the chain is broken...
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