What if, it merely needs a PDOWN pulse to awaken it under those conditions? If this were true, then it could save a lot of possibly unneeded repairs.
... maybe I'll just try connecting it to pin 42 of the DSP, which is given a proper low reset pulse sometime after power-up. This could be all that it needs.
BINGO!!
The "dead" cs4231a in my Mk2 player now works again!
Note that the PDOWN line (pin 18 of the cs4231a) is normally wired to Vcc
underneath the chip, so one must lift that pin in order to perform this modification.
At the other end, the RST (reset) line (on pin 42) of the DSP can be used as-is.
Some blobs of hot-melt glue help keep the whole thing together.
This surefire fix really beats the hit-and-miss approach of completely replacing the chip.
Cheers!
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