So my friend bought an me an amp the other day, and as I plugged it in, the thing started smoking. Took the chassis out of the cab, and when the smoke had cleared, I saw some burned resistors and such on the circuit board: The amp is a 60 watt Fender solid state BTW. Not sure what the specific model is, but I can check when I get home. Looks simple enough to unsolder and replace the resistors in the burned area. But what would be the root cause and how would I find it? I guess I can test the effected parts for continuity and resistance, but what else should I do? What are those black squares with 3 lugs that screw into the heat sink? Grounding lugs? Can I even get those as replacement parts if they need to be replaced? Thanks for the help, all. I've rewired several guitars, but haven't messed with amps much other than replacing an output jack or a speaker.