Gotcha, more or less what I was planning on trying via oscilloscope. Issue I had was that the CPS1 B board's in the way. I know people use rigs that moves the B+C to the bottom or similar, but I'm not up to building or buying such a thing. I guess I could try measuring from the bottom of the board. Will consider that next.yes and no. An audio probe is a device that's basically a metal pin attached to an audio amp and a small speaker. so you can touch a pin on the circuit and "hear" the data on that pin.
think of it like an oscilloscope with audible output instead of visual
using that you can check the output pins of every chip in the audio circuit to determine where the failure point is.
you might be right that one of the clone parts damaged something else, but heck that can happen with some original parts fail too, it's best not to jump to conclusions until you've gone through all the basics first.
Checked pins 8 to 12 which should be the analog output of the YM3012 DAC, get a constant low buzz (which is what I hear from the amp if I crank up the volume a bit). So issue is either with the YM302, or before it.