Schwaggs New record! You're half way to solving my problem a year before I even owned the machine. I'm having a similar problem with my new FirePower...

Test switch produces sounds (no speech) but there is no sound in game at all.

Sound Board J3 pins are all high (no pulsing). Does that mean that the sound commands are not reaching the sound board?

Assuming so: IC5 on the Driver Board tests LOW across the address bus (pins2-9 and 10-17). Should they be pulsing? The data bus still pulses... This is where sound commands come from right? (not sure on this...)

The other two ICs on the driver board(IC10 and IC11) are mostly pulsing on the Address Bus, but there are a few legs stuck high or low. Do I need to check those for bad resistors or diodes?

Another friend told me the SOL PIA address bus should stay low until triggered... so maybe thats not my issue. Still not sure about the other Address bus legs on the other Driver Board PIAs though...

Did some more testing: sound commands are in fact getting to the board just fine. checked some ICs on the sound board, replaced the PIA (that was not the problem).

I found that if I unplug the speech board I can get the faintest sounds to play (barely audible) and another guy helping me out says the AMP isn't in line if you take out the speech board, so that kinda makes sense... thinking maybe there is a problem on the speech board now?