The new revs ain't missing caps IME, what fixed it for me was resoldering the flash memory connections, see my post above
I just purchased one too, and it is a rev.4 as well. I suppose it will be a good idea at some stage to replace the FMZ caps with a better brand, but that can be done late i suppose. Is it also better to remove C3 completely, or not necessary? Also, i had read somewhere that the 161 is not...
www.neo-geo.com
For me, PCM sound works, it's just that it has random loud cracks when there's too many PCM sounds playing at once.
It doesn't happen consistently. Like you can go through the intro to let's say, kof 97 without any issues, but on the next playthrough, some sound doesn't play correctly and sounds distorted similar to your video.
Have you had an issue on the newer revs and reflowing the flash memory helped clear up the loud cracking?
Also, I could swear that adding those 47pf caps made the issue happen more consistently. Unsure if that's possible.
I might try removing the caps at C5 & C6 and replacing them with just the 47pf caps to see if anything changes.
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EDIT: Reflowed the flash memory chips on both the IC side and the connector side. No change in sound quality. Replaced C5 and C6 with just the 47pf caps. No change.
Original C5 and C6 values are ~0.15 nf = 150 pf if that's useful to anyone.
The only thing I could think of trying is to change out the caps near the voltage regulator. Maybe when there's too many PCM sounds trying to play at once, the crappy chinese caps get overwhelmed which causes the PCM sounds to come out messed up and breakup?