Martin: I was fixing an issue with the polyphonic aftertouch on my CS-80. A cluster of notes was going full volume no matter how softly I played, and I'd traced to the problem to an open on the +15V aftertouch sensor rail, which I fixed with a jumper, and while I was in there removed all the keys and poly AT sensors and cleaned everything. As a side note: I found out later from a local tech here outside of Philadelphia (he services CS-80's, Paige Hamilton's CS-60 and a local GX-1), that one should be careful with what kind of cleaner you use on these, if any, as they are infused with a resistive material that can be drawn out. I used Tascam RC-1 rubber pinch roller cleaner, and am hoping I didn't do any damage.
So long story short, I forgot to pull the keyboard chassis forward before lowering the card riser, and the metal 15V rail crunched into the PCB's at the rear of the keyboard chassis. No big deal at the time, I thought, but when I powered the CS-80 back up, all the oscillators were firing, and when I started jiggling a few wires I heard a pop, which was likely the 500mA fuse blowing, and then silence. I powered it up a few times thereafter, but all I heard was a high-pitched wine and a white noise hum, and haven't turned it on since, but now that you've validated the resistance I should expect to see between the card rail and ground, I'm going to recalibrate the power supply and fire it up and see what happens.
D T: I think I'm guilty of both on M-Wiggle! I expect to continue to be confused by the engineering of the CS-80, but I am enjoying learning how it works. I haven't heard about Old Crow's voice card project, but did hear back from him recently about a KAS board YM26600 retrofit he's been working on.