Today I've been fooling around with our broken WPC sound boards, trying to get some disabled ones up and working. I've come across one with a really weird problem. It will play some sounds, but tends to become frozen or spit out garbage on others. It also seems to be making inapropriate sound effects calls. For example, I'm testing boards in a Fishtales today. If I start a game, I get game music, but not the normal "Gone Fishin'" noise. It will play some effects fine, like "How big was it?", but chokes on the sound for completed LIE. If I go into test mode, it will start to play the music, but you'll hear dial tone SFX in the background. If I try to play the tropical music, it becomes stuck on one note.

With the incorrect sound calls, I figured it was the 74ls374 IC chips going bad, but I replaced those and still have the same problem. I swapped out u13, u10, and u11, because they're easy. No luck there. It's not the U18, because the same rom works in other boards. Before I go through and replace all the chips one by one, any suggestions on what might be causing this?

Ah, Fixed it. Answer was U9, the memory. Luckily, some past tech had ordered a few spare chips, so I popped a new one in there, and after some minor trace fixes, it's good as gold. Whee! Weird that it passed the self test, though.