Hi! I will update this post as I get along with pictures and schematics (if needed), but I wanted to throw out a request for help; I am in the process of repairing a PDI 6050A, whose symptoms were negative output, current limit lamp flashing, very small voltage when the voltage is turned all the way to 60V. I will list a more detail later, but suffice to say that there was a blown internal fuse (on what seems to be on the isolated side of the mains transformer) on the input to the unit, which I replaced. This solved the flashing current limit lamp, but I am still getting a negative voltage on the output.
I have verified that all the transistors and diodes seem to be functional, and have checked that none of the big caps are shorted (I haven't checked all of them yet). I also checked the voltage and current control pots: these seemed a little out, but even when shorted or removed, there was no obvious change on the behaviour.
I am at the point where I need to trace out the circuit, and I wanted to ask if anyone has the schematics for this unit. If not, I will begin reverse engineering the board tonight.
EDIT: robrenz, I saw your post about this; did the manual(s) you bought contain schematics? For the 6050A? Thanks!
EDIT: just called manuals plus, and they confirmed that there are schematics for the 6050A, so ORDERED!
Cheers!
Chris