Carvin unbalanced rails

[Sowhat]

This may seem like a dumb question but this is the place for that, right?

I have a Carvin R600 biamp in for repair that is really screwed up. Here's how I got it...



After straightening, cleaning and replacing missing hardware I got it cobbled back together physically. I disconnected the power supply from the rest of the amp and checked the +- rails, I get +34.5V and -64.5 volts. This could be a big problem. This is just a simple transformer/bridge rectifier/filter cap supply. With an ohmmeter incircuit I checked the bridge and it looked pretty much good to me. I ESR'ed the filter caps and they look good as well. I'm thinking that the bridge can be the only possible source of this imbalance. Anyone ever come across a bridge that checks out good in unpowered test but fails somewhat under load? I don't want to start unsoldering stuff if I don't have to.

I said under load which is not true, I took these measurement with the power supply still disconnected from the rest of the amp.

[Enzo]

Scope it. or at least measure the AC ripple on the Dc, and see if your 34vDc is not also a similar amount of AC. Just because your cap measures OK to a tester doesn't mean that it IS OK, nor does it mean that it is fully connected to the circuit.

It is appealing to focus laser like on a bad component being the problem, but test every part in it and you will never find a cracked solder joint or broken copper trace.