Moonwalker sound & graphics glitch

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c0nn0r
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Moonwalker sound & graphics glitch

Postby c0nn0r » Sun Feb 03, 2019 4:02 pm

Hey gang, I have a desuicided Michael Jackson’s Moonwalker PCB here that I bought as non-working, and am making the attempt to fix this bad-boy myself.

There are three separate issues:

(1) Missing foreground sprites (bad IC-17 - Sony CXK5814 chip)
(2) PCM audio from the rebranded Ricoh RF5C68 smt chip (rebranded as ASSP 5C68A) is garbled
(3) Board fails half of the V.D.P. test. I’m not sure what this is, nor can I see any adverse effects on the graphics (aside from the missing foreground sprites) - perhaps this is a symptom of the bad IC-17?

Questions:

(1): Where can I buy working replacement parts for the chip st IC-17 - Sony CXK5814 or compatible?
(2): Where can I purchase a working replacement RICOH RF5C68 chip?
(3): What the deal with failing half of the V.D.P. test?

Here’s what I know thus far from my research and testing:

(1) Foreground graphics issue is likely tied to a bad work-ram at IC-17. I know this because the excellent memory test SEGA provided told me (and per this post: [url="https://forum.arcadeotaku.com/viewtopic.php?t=11206"]https://forum.arcadeotaku.com/viewtopic.php?t=11206[/url]). It looks like a previous owner attempted to fix this issue as the current chip at IC-17 is socketed. Looks like they just socketed the same chip as it matches the one at IC-16. I took out the chip, cleaned the pins and re-seated it. Still comes up as bad.

(2) PCM audio from the RICOH sound chip is garbled. FM synth still working properly, so the z80 is probably good. Pretty sure that I need to replace the RICOH chip (as per: [url="http://www.jammarcade.net/michael-jacksons-moonwalker-repair-log/"]http://www.jammarcade.net/michael-jacksons-moonwalker-repair-log/[/url]), but am having a tough time sourcing a replacement part. I’d prefer to buy a NOS chip, but as I understand it the same chip is used in the SEGA CD, so I may have to take one from scrap.

I’m hoping that if I can manage to replace these chips I will have a working Moonwalker.
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