Ah, so with just the +-5v gnd +-12v, the dacs should operate properly? Honestly, I'll replace them anyway, but learning to power and identify issues with ICs is probably a worthwhile skill
Don't replace until you test. You can do more damage with random replacements than you might expect.
Never mind, you already did.
Here is the challenge with what we call "Easter Egg" repairs:
You think it is the Chip at A9, so you remove that and replace it. That didn't fix it. So you move on to the next chip and replace that. That didn't fix it, so you remove and replace a diode. That didn't fix it. So you remove and replace another chip.
And that didn't fix it.
What you don't know is you left problems at every chip you removed and replaced. In each one, you had a bad solder connection or damaged trace.
Which makes fixing problems harder (because now instead of 1 problem, you have 4 more added to it.) It is much harder to fix a board with multiple problems, as sometimes each of them can stop the board from running correctly.
The moral of the story is to "work the problem."
Develop a problem statement: Game is playing blind. I can hear the sounds, and get no "Beeps" on self-test.
Now list what can cause that.
Now figure out how to TEST what can cause that.
Then test each component to see what it is doing, and make an educated repair.
Otherwise, you can in some cases, chase your tail forever.