Yeah, I have a pretty good understanding of returns on circuits, etc. Here's an example of the kind of thing that just leaves me shaking my head--on the 5/12V PSU that came with the machine there is a terminal labeled 'acg' (third from the bottom) and another one labeled 'fg'. I left this in place as original, so the wiring is original. The bottom three wires are the input from the main power supply, so the ground wire (acg) is connected to main supply and cabinet. The fg ground looks as though it's supposed to be separated from the main ground, so I figure that's a return for anything using that power supply. But if you look close you'll see there's a jumper tab connecting both ground terminals, so effectively the return ground is the same as the machine ground. What's the point of having separate terminals on the PSU if they're going to be connected anyway? Maybe there's some other application that requires it, but not in this case?