Finally got most of the sound fixed on a Stern whitestar board in a Playboy but still have one issue.
The games sound was very loud and distorted and did not adjust with the volume and I fixed that.
Replaced all the electrolytic caps, the 2 main amps, the 7805 5Volt VR, the U30 LM833 Op amp and finally it was the TDA1543 DAC at U26 that was causing the issue.
So now the sound is almost normal, but the music has distortion on all of the bass notes. When running the sound test the test tone sounds fine. The speech roms tests sound fine, the sound effects in the menu sound fine, the high notes in the music sound fine, but the bass notes are distorted. It is distorted on both the upper and lower speakers. It is distorted at both high and low volumes.
I've tried a new eprom at U7, a different BSMT chip, I swapped the two 6809 processors.
Is there a mixing resistor that adjusts the bass and treble on the board, maybe one has been damaged from when the DAC blew?
What about the 10 uf tantalum cap at C35? It's across the TDA1543 chip that was causing the main issue.
Any experts on this board?
Schematics here
http://gamearchive.askey.org/rom%20archive/pinball/Sega_Data%20East_Stern/CPU_Sound_Bd.pdf