For a start maybe you should check +12V and -5V at the PCBs connector if this is easier for you.
thx sascha, i think i've isolated the problem now: it's the +12v line!!! on the edge connector i get something like -0.25v for +12v, -5v is well within limits. with that result in mind, i started tracing back the problem. let's start from the beginning with the huge power transformator. we've talked a lot about those wires on the left of the transformer's secondary side, but we never talked about all those colorful ones on the right. all the voltages coming out of the transformer's secondary right side are correct!
all those wires (you can see them at the very bottom of the following picture) go into a small pcb (don't know what it is called) which is also part of the power supply. from what i understand, this pcb creates the -5v and the +12v.
all that's coming out "on the other side" of that pcb are a couple of wires: green is -5v, red is +12v, black is GND and white i have no idea, but it "gets lost on its way to the pcb", meaning it ends in a connector somewhere in between. when i measure black and green i get -5.19v, but when i measure black and red i get ZERO volts (when measuring red and white i get roughly -2v). this means -5v is coming out nicely here, +12v is not!
so the problem has to be on that small pcb somewhere and i'm pretty sure i've isolated it already! right before those red and green wires there are two ICs on the board, ic1 is for +12v (red wire) , ic2 for -5v (green wire).
when examining those ics closer you can clearly see burn marks on ic1 (-5v) and when looking back at the start of this is remember some smoke and a strange smell coming from somewhere on the power supply. perhaps this is where it started all!!!
now what i could do is replace that IC, but how about removing that small pcb entirely and hooking the -5v and the +12v directly up to the switcher. john "we are in the basement" has a similar setup without that board and when looking at one of his picture you can see that all the wires on the secondary side of the transformer have been removed, the small pcb is gone as well and the red and green wire are hooked up to the switcher. do you think that would work in my case as well? my setup is slightly different (+5v coming from somewhere else), but i've got the feeling this should work ...
what do you think? give it a try? or try to repair that ic / pcb?
