Does anyone by any chance have schematics for an Ampeg SVT3 Pro U. It's the "U" that's the tricky bit. This version has an additional board at the back, which produces a balanced / unbalanced line out signal via either a jack, or an XLR connector. Also, there is a level control, and a "Pre - Post" pushbutton switch. One of those signals is missing, so you only get output with the switch in one position. Also, the level control doesn't seem to do a lot, but when you look at the print, the pot is actually connected as a variable resistor. I can see the connector pin on this extra board, where the signal that's missing should come in, but without taking the main board right out, I can't see where it should be coming from at the other end. So if anyone has got this version of the schematics - there are plenty of the 'straight' Pros on the 'net, but apparently, not this version - then it would be handy to get a squint. As it happens, this was not the main fault, which I have already fixed. It was an owner's "can you just have a look at this other little problem, while you've got it". To be honest, I'm not even certain that it is a problem. I could be missing the function of the switch and pot completely, I'm just taking the owner's word for it, that there should be signal there in both cases.
TIA
Arfa