I had mentioned this problem in another thread I started but thought it should get its own because it's returned and I'm out of ideas.
My Firepower is pretty much done. The exception is I have the wrong sound effects and voice calls being played at various switch hits. For example "Fire 1" is said when one of the center targets is hit. The shooter lane switch activates the higher value spinner sound and so on. The background "music" is not played at all. Sound test reveals that all sounds are present. When I change the dip switches on the sound board to turn the voice off and to activate the stupid chime noises they seem to work properly. I've never heard a Firepower playing these sounds so I can't be sure but they seem consistent with the switch hits that are made on the playfield.
I mentioned that this problem went away before. That was after reflowing solder on all the connectors on the MPU and driver boards. However, after a couple games it went back to the wrong sounds when I had started a new game. Today I removed all old solder on EVERY connector pin on the MPU and driver boards and flowed new. This includes the 40 pin which tests fine. All socketed chips have been removed, cleaned and reinserted. All sockets are RN and are tight. Problem remains.
I've read that sound issues like this can be caused by five particular transistors at the bottom left of the driver board that are for the switches that determine sound effects. I've tested all the transistors and they test fine. Scores are accumulated properly at each switch hit as are lights when applicable. I've also checked continuity from the driver board to the sound board and that tests ok as well.
I'm thinking this may be a sound board issue but am at a loss as to where to go next. Any suggestions would be appreciated. I've added a photo of my sound and speech boards for any of you System 6 experts to see if anything looks incorrect.