This board was worked on well before I got it. But thanks for the One To Grow On!

The Base of Q1 is connected to ground, the Emitter is connected to Pin 4 of the DAC, and the collector looks like it's connected to the +5v thgrough a 3.9k resistor. In all the diagrams I've seen of transistors, the Base is usually connected to some small amount of voltage so that the current can flow between the collector and the emitter. Maybe I'm looking at the wrong diagrams, but I don't quite understand how connecting the base to ground enables current flow.

I'm not saying you're wrong, but if you're right, I don't know what I can derive from any of the readings I get from Q1, since I clearly don't understand how it's being used in the circuit. It definitely seems to be the thing that ultimately puts signal through C8 and into the op-amp at U17, though.

I have switched this game on and off and on again more times than I can count. That's not the problem. Thanks, though!

Are you thinking that the wave generated at C8 is the output of the analog signal put out by the 1408 DAC? If so, then I can confirm that I get very little from C8 during music. I can crank the volume way up and hear a scratchy rendition of the drum intro to Sound Test 02, which is the multiball theme.

Also, I'm getting a weak "bong" sound when the sound board boots up, though it dies off really quickly. I get this tone every time I do anything that reboots the sound board, such as hitting the CPU reset switch or going into the Music Test. It's possible that my C8 capacitor is having problems. I'm going to Fry's tonight to pick up a couple of new Q1 transistors and some new capacitors for C8. Let's see if that helps.

OK! Drums again - and on both sound boards!

I replaced the Q1 transistor and C8 on both of them, and we're back in business. I also replaced R16 on the first of the two boards as a just-in-case measure while replacing the other two components. In retrospect, though, I probably didn't need to do that. It's also kinda big, since I had to use a 1/2 watt instead of a 1/4 watt, so I may put the proper size and spec one back in before giving the board back to its owner.

Next up: Bringing back "Yo, Taxi!" and other sounds.

I have a hunch that the op-amps at U4 and U5 are bad. Pin 1 on each of them have very little output voltage, despite having strong input signal. I get a small amount of output when the knob is set to .5 volt/div. If I move it to .2, then the signal disappears from the screen and I can't do anything to get it back unless I go back to .5 volt/div.

So, wayout, if you could test the signal at pin 1 of U4 and U5, that'd be great. If your data is what I'm expecting, then I'll pick up a couple of op-amp replacements and see if that works.

"Yo, Taxi!"

And we're back. Replacing the two op-amps on the MPU gave me the last of the missing sounds. The common thread was the bridge rectifier on the power supply which, I believe, supplies the -12 to the system. I don't think it's a coincidence that nearly everything that broke was related to the -12 line. I don't know enough about electrical systems to understand why only those components got fried, but this whole experience has motivated me to pick up an Arduino, a breadboard, and some other components to start experimenting with electrical circuits so I can really have an understanding of how all this stuff works.

To the people who (actually) helped me out, thanks! I really appreciate it. This would've been much more difficult (if not impossible) without you.