Yes. First check the voltages to the sound board. If that doesn't help check the ROMs, veridy each ROM on the sound board as well as clean their sockets. Also check any connections between the sound bd and main bd. The cables are old and may need flexing, try flexing while in game and listen for changes. If none of the physical provocation helps then you need to go into the logic. You'll need a logic probe, preferrably.
You have probably checked already but if not, make sure your voltages are ok. I had similar issues with a SF2 pcb and turned out the YM2151 was doing strange things because it wasn't getting enough juice since I was using a crappy JAMMA extension which only had one +5v line. Checking at the board it was only getting 4v.
Yes. First check the voltages to the sound board. If that doesn't help check the ROMs, veridy each ROM on the sound board as well as clean their sockets. Also check any connections between the sound bd and main bd. The cables are old and may need flexing, try flexing while in game and listen for changes.
If none of the physical provocation helps then you need to go into the logic. You'll need a logic probe, preferrably.
You have probably checked already but if not, make sure your voltages are ok. I had similar issues with a SF2 pcb and turned out the YM2151 was doing strange things because it wasn't getting enough juice since I was using a crappy JAMMA extension which only had one +5v line. Checking at the board it was only getting 4v.
Gotta check those voltages