Guardian Audio B82M (with schematic)

[goldtop5]

I have a Guardian Audio B82M (Mott Audio) powered mixer head that's distorting on the main outputs. The monitor outputs are as clear as a bell, but can't figure out what could be causing the problem. Any ideas? (Schematic included)

[g1]

You mean the main non-powered outs, not the speaker outputs?

[goldtop5]

Speaker outputs

[g1]

So can you route the monitor outs into the power amp inputs and see if the problem is in the amps ?
And I guess you have verified that the speakers are good?

[goldtop5]

I've tested the outputs coming off the preamp section and they tested good. It's only when it passes through the amplifier section to the speaker outputs, it is distorted. We have a test bench speaker here at our shop which we know is working good.

[J M Fahey]

Well, then you'll have to scope the power amp out and post a picture of what you find.

[Jazz P Bass]

Here is the schematic in a pdf format.
that .doc was too hard to manage.