Peavy Xr-400 Mixer Amp / Need help for repairing

[l4rtt-1]

Hi!

I have Peavy xr-400 mixer amp. The power amp schematics (which is peavy 200h) can be found here:

Peavy 200H module

When i got it to myself, it seemed completly dead, power(indicator) led in didn't light up. But when i unplug the upper(upper in the 200h schematic) connector of the transformer secondary and plug the the lower which gives power to the preamp/mixer section and put on a new 2A fuse, the power led lights up when powered up and the DC voltages(about +15,5V and -15,5V) for preamp section are correct(as they are in the schematics). But every time i plug the upper transformer secondary connector to the power amp section, the fuse burns out and so the preamp and power led won't get power either.

So the problem is somewhere in the power amp? When i measure the AC voltage in the upper transformer connector(when it's unloaded) the voltage across Red(R in the schematics) and Red(R) wire is about 69Volts. Is this correct or is there something wrong with the transformer? If transformer is ok, which components should I start checking? Do i need to take the components away from the PCB to test them?

Any help would be great, it would be nice to get this old amp working!

Thanks,

l4rtt-1

[52 Bill]

Start by testing the 4 output transistors for shorts. Next would be the diodes in the rectifier bridge.

Most times, it will be a shorted output transistor. If you do find a bad one, check all of its related parts like the ballast resistor, driver transistor, etc.

[ron vera]

Peavey XR400

do you still have an active link for the schematic diagram for the Peavey XR400 mixer Amp? The one posted on this thread is no longer active. Thanks

[DrGonz78]

Well here are series A and B not sure which one you might have.