Was able to spend a few hours trouble shooting tonight... after working on my drifting for about half an hour

Okay, so I've made some good progress towards figuring out what is wrong. Disclaimer: If I would rip the cabs all the way down and just work the boards I'd probably have this done right now but I'm trying not to pull everything out if I can avoid it and it doesn't look like I can. Also - I broke my multimeter several weeks ago and haven't replaced it yet. Heh.
Unit one functions normally.
Unit 2 gets power to speakers and monitor.
Unit 2 gets no power past the power supply. According to guy I bought it from boards from unit 2 work in unit 1.
I assume he's a straight shooter.
I separate the wiring harness that is linking unit 2 to unit 1 and wire a power cord to unit 2.
I notice that unit 2's power supply doesn't seem to be getting power at all. Same behavior as when I first plugged it in.
Check bank of fuses between powersupply and transformer - none popped.
Take unit 1's power supply and wire into unit 2. No dice, power supply won't stay on longer than a second and I begin to smell that magic smoke we all fear. Kill power.
Put U1 powersupply back in U1. Still works. Yay.
Put U2 powersupply in U1. That works. Yay.
At this point logic seems to tell me that:
1) I need to replace that multi-meter before going further
2) Something is clearly amiss.
Went back out and ran separate wall power directly to the power supply, it is still tripping and none of the boards show power at all, it trips right away. Tomorrow I'll pull the boards and see what's going on. I thought it was between the power supply and the wall but I must have overlooked something. It would be better if I knew what I was doing but I'm very unfamiliar with this machine and oh my there sure are a lot of boards in there
