Need Help with my Beta Lead - No main power

[dkonopka]

I just purchased a used Beta Lead head after a lot of searching.  The head works, but only the preamp, meaning master volume control is dead and I only get the distortion side of the amp from both channels.  Main power is gone.  I took it into a repair shop and they thought everything was fine, but this guy does not understand guitar amps.  I have to take it back to him and try to explain that the amp is not repaired and that it is working at only half power using only the preamp.

The master volume knob does not work and actually makes the amp go down in volume when you turn the knob to the right.  Can anyone help me identify the problem?

[kingnimrod]

Possibly power amp output transistors? I had a somewhat similar issue and ended up replacing almost all components on the power amp board on my beta bass before I realized what was going on. Run a line from each of your preamp outs and master accessory, one at a time, into another power amp ( or effects loop return on a combo amp) to make sure the issue's not in the preamp. If it sounds fine, check with a multimeter the values of the 6 output transistors on the edge of the heat sink that holds the power amp board in place. It's common for those to go. You'll also want to check the board for leaky caps and blown fuses and diodes. But check those transistors first. If they are bad, other stuff will continue to blow until they are replaced.