Been helping a friend clean up his new pin; thought we were done, then when he was playing it, within the course of a game the speech became somewhat garbled. It started out as mis-matched sayings, then seemingly entire phonemes and getting a bit worse, but still 'working'. The background sound had been working up to that point.

We powered down and back on. No sound or speech at all. Occasionally there are some constant clicking sounds but other times pure silence. Reseating every connector, powering down overnight and back on, nothing brings it back other than the occasional clicking sequence. Meters fine at +4.98V and +13.3V. Volume control was not staticy before problem nor after, can clearly hear it being adjusted.

Any ideas where to start? I may pull the eproms and dump them, but the chance of every one going bad at once is a long shot, so suspect some addressing issue prior to that point? Any help is appreciated!

As stated, all cables already pulled and reseated. (Also rocked when cold and warm). Capacitors tested fine for voltage, also just tested for capacitance and fine. They are on the list to replace regardless, but this is acting like a digital addressing problem, not an analog filtering/amp problem.

Thanks everyone for the suggestions. After much looking, testing on the board, and a ton of reading online, followed by a search through my spare videogame boards for a rare chip, the problem is now fixed.

It was caused by a crappy AMI brand 6808 CPU dying on the sound board (U9). Replaced it with a Motorola 6808 and speech and sound are back in full. (I may pop in a 6802 instead since the Williams board is capable of handling that without any mods unlike Bally's)

Thankfully that one was socketed, while U10, the PIA was soldered. Was definitely hoping it wasn't that!

Yeah you can, by default the RE (ram enable) line is tied to ground which disables the internal memory. Williams tied it to gnd, vs. Bally that tied it to +5 which enables it, so on a Bally you have to cut the line and ground it to use a 6502 without problems.

On the Williams you'd have to cut ground and go to +5 to enable internal ram, then pull out the ram chip.