These little sound boards in WPC era Bally/Williams games can be difficult to track down issues on and there are no inexpensive reproduction replacements, so the boards themselves are quite expensive if they need to be replaced.
A client brought this board to me. It wasn’t getting the usual start-up bong or any sounds on his game. The game would stay in test mode for about 8-10 seconds, boot up, but no sound whatsoever.
After making sure the ribbon cable wasn’t the problem or the already socketed chips on the board, I did a little sleuthing and with fairly high certainty determined the U9 RAM to be the culprit. I socketed and replaced the 28-pin 6264 RAM chip, plugged the board back in my test machine and viola, working A-12738 sound board.
I’ve ran into this failed RAM issue twice now on WPC sound boards. Sometimes similar issues can happen with bad I/O buffer chips, but it seems this 6264 RAM is failing with a little higher rate as these boards get older.