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Hello - I am a better musician than electronics repairer, I'll try to make this brief. My 94 vintage amp has had two 1/4 Trs inputs, one totally crumbled, the other similarly falling apart, so I ordered new ones from Allied and started putting it all back together. I was substantially done, and had one of the two inputs working just fine when I held it just right, then after a bit of fumbling neither of them worked. On my amp the jacks are not soldered to a pcb, they are just locknutted through the front plate. I have not located a schematic that is for the correct year, there is one for the '03 version. The two TRS input jacks are kind of wired parallel and also jumpered over to a "tuner" input and an XLR DI input. My fear is that I have one (or more ) of the connections wrong, except that, as I say, I had the one TRS jack that connects directly to the volume pot pcb and to the house ground working like a champ briefly. Before I chuck my beloved amp, I thought I would check and see if there were someone who might suggest how I have muffed such a simple task and, perhaps, work toward a basic grasp of the elements of the nearby components to which the inputs are connected. The 1/4 TRS inputs have two sides, the "tip" side and the "ring/sleeve"side, and are on one side connected to the condenser pot array pcb, and also to a bigger black wire which goes to the house ground, and then there are two connector wires ( signal and ground ? ) to the main pcb, one marked "IN " and one unmarked. "IN" is a single conductor where it connects to the main board but oddly has a an extra bare wire coming out the other end where it goes to the TRS jack. The other unmarked wire is a simple pair going between each side (signal and ground?) of the TRS jack and two nearby corresponding terminals on the circuit board. I had a 50 percent chance of guessing it right, but I didn't. I could post some illustrative closeups of what I am seeing if that would help.
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