Heeding your caution about costs, I decided to do some more investigating since the chassis was already out of the cabinet. Before I even started probing for loose connections/wire I noticed something else, a blob of what I assume to be white thermal conductive paste on the edge of the PCB adjacent to the leads of the power amp chip (right side as viewed from the front). This gunk was on top of some of the SMT pads where some of the caps dropped from later revs of the amp would have been. I assumed that if this stuff is thermally conductive it might be electrically conductive, or at a minimum, have some sort of resistive or capacitive effect. At any rate, I cleaned this stuff off the pads, hooked things up and, voila, the amp is working like a champ. I'm still wary since it used to fail intermittently, but I'm cautiously optimistic that this was the source of my problems.

I have a Spider 112 that's exhibited the same symptoms (no output). Actually, it began with intermittent cutouts, and now output dies almost immediately. When this has occurred I've plugged in headphones and verified that the preamp/modeling side of the amp is working normally. After reading this post I took the electronics out of the cabinet. My board doesn't have the SM caps that were dropped from earlier revs. There's also no trace of burning or arcing around the power amp chip.

Diagnosing and repairing this amp seems beyond my skill level. I've already paid a local guy (RI) to check it out about two years ago when the failures were intermittent, and he claimed it wouldn't fail for him. I don't have any confidence in him. So, my question to you guys who I assume to be pros is, could I ship the chassis to one of you since you seem to be familiar with the vagaries of this amp? I really like it, especially for it's clean tones, and I'd rather not junk it.

If interested please PM me or let me know how I can reach you to negotiate the details. Many thanks.

Jeff