Peavey musician 78' mark 3 400 GH.. no output

[wheatley]

i have a 1978 musician mark 3 400 GH head that powers up but produces no sound at all. i open it up touched up some cracked solder but still the same problem. when turned on with a light bulb limiter the bulb flashes bright then dims quickly, as it should i believe.
i plugged the 400gh preamp out into another amp and a 1/4 inch into the 400gh input and the signal traveled through the preamp to the working amp.

does this mean its a power amp problem? to test output voltages and voltages on the board should i measure to ground (the case)

also the lights for both channels stay on despite what input i use ( channel 1, channel 2, and auto mix)

[olddawg]

Does this amp have a main in jack or effects in? If so have you tried imputing a signal there?

[wheatley]

it has 5 regular inputs, 2 for each channel and one auto mix in. then under the 6 band eq there is an in/out for each channel, a preamp out, line out, and power amp in. plugging into these yields nothing through a cab.

ps... i forgot to mention that there is no dc voltage at the output, which is good right?

[wheatley]

while messing around with it i found that the solder bridging the main and auxiliary outputs on the back had broken. i re soldered it and works fine now... easy fix

[Jazz P Bass]

Good find!