Well, it was a strange situation. I replaced every electrolytic cap on that board, as well as the next chip up from the Crystal, I don't recall at the moment what chip that was, but that, as well as the Crystal too at Oliver Kegali's suggestion. I could NOT get it to stop making the noise! As part of the diagnostic procedure, I plugged the entire board into my Silverball Mania - Very odd to hear those noises coming out of the SBM. And plugged the SBM board into the Future Spa. The latent beeping noises followed the sound card to the Silverball Mania. So I put the boards back.
I found a buyer for the FS, so in the interests of not selling a game with that problem, I took the SBM card out, and swapped the U7? chip with the FS so the sounds would be right, and then I figured I'd get a new Card for the SBM at some point.
Now the really strange part- When I switched Eproms, All the sudden the sound stopped!! They both play perfectly, and neither one makes the noise after end of game, and letting it sit for several minutes! I'm wondering if maybe the act of plug/Unplug of the Eprom caused the board to start working? Like corrosion on a pin or something. There was no obvious corrusion on either of the pins for either chip, they both appear to be gold plated.
One strange thing though- and maybe this has some bearing on the situation - the Card that made the beeping noise, was a little funky, in that if you put it in the game, and screwed it in completely, that is, tightly, then it wouldn't work at all. When you put it in the FS, and tighten it up completely, the game woudln't even boot. It would give 5, or 6 flashes, but- loosen the board a little and everything was fine! (except for the beep after end of game) I noticed it again when I screwed the "Bad" board into the SBM, and tightened it down, the game would boot, but there would be no sound at all. Same situation though, when I loosen the screws just a little bit, everything as fine. And this time there was no beep!
I wonder if there was some trace that had a crack, or a connection that would get grounded, or something of that nature so when you tightened up the board it would causes a broken trace. No telling. Anyway, for now it seems to be fine. Still, I wouldn't mind having another Bally sound board of this vintage.
-Brian Prenovost
Silverballs Arcade & Showroom
New Port Richey, FL
