Mike -

It sounds like some problems I had when I bought a dead JP. One of the things I found was lots of blown fuses and shorted transistors on several of the boards. (Happily, none on the MPU!) After replacing all of that, I noticed black marks on the ground plane behind the circuit boards, especially the upper left board. It appeared that the heat sinks for the transistors were arcing to the ground plane, causing all kinds of problems. I ended up installing some film to create an insulated barrier between the circuit board and the ground plane. (Don't isolate the boards from the ground plane! Your ground reference will be using the wiring to the boards and the metal screws that hold the boards to the ground plane.) Since then, no more blown fuses and transistors.

Methodically go through each board, checking all caps, transistors, and fuses. Any toasty connectors - replace both sides - the plug and receptacle. I like trifurcon pins best. Shotgunning will only lead to frustration. (At least for me!)

Good Luck and report back with progress.

Bill C