I wrestled with the sound on pinbot recently. Here are some things to consider:
The main sounds (switch hits, and such) and all the speech, are generated by the sound CPU on the main board. The background music is what comes from the sound board. For me, all I was getting was background music.

I believe there is a trimmer pot on the sound board that mixes the two signals together. Give a few wiggles to see if it helps. They can get dirty and finicky.

SOUND TEST will run through main CPU sounds and speech. MUSIC TEST Runs through sound board sounds (music, of course).

People tend to have success when changing the CVSD chip, but I like to KNOW that's the problem before I change it.

No, this doesn't give you an answer, but might spark something for you.
Good luck,
Jeff

Dupe post. Stupid Internet.

If you're talking the main CPU board, they're both Sys11A (with same part numbers), so there shouldn't be a problem trying it out. Officially, you'd need to swap the sound ROMs AND the game ROM(s). But if you do it systematically, you can take the opportunity to test your ROMs in the board that you know works, if you know what I mean.

If you're talking about the sound boards, they appear to be different part numbers in the manuals, so I'd be careful with that. Check the schematics and see if the signals are similar.