Peavey PV-1200 Power Amplifier

peavey pv1200 bench test

Repaired Channel

My curiosity got the better of me. I replaced all burnt resistors, opamps and transistors on the pcb. For testing purposes, I soldered in only one pair of outputs. There's no necessity to have all the power transistors installed unless I plan on having the PV-1200 back in service.

Signal Ground

In order to get the test signal to appear at the output of the amplifier, the entire module must share a common ground.

Photo on the right shows a jumper from 0V to the signal input ground.

For convenience, I used the inverting input (Bridge) of the opamp. If I had used the non-inverting input, I will have to ground the inverting input. More work.

peavey pv1200 pcb copper side

Square Wave Display

peaveypv1200 1khz square wave

1kHz Square

peavey pv1200 10khz square wave

10kHz Square

The 1kHz and 10kHz Square wave show severe overshoot. I doubt it is originally like this. It can be rectified, not an issue. What is important is an undistorted sine and square wave output.

Original Square Wave

The 10kHz display on the right is from the undamaged pcb.

There are no signs of repair on this board, so we can assume that this is what the PV-1200 actually looks like.

It's not as pretty as I like it to be but at least, the overshoot is contained.

peavey pv1200 10khz original square wave

10kHz Square

What Now

For the time being, I'm content to just mothball the two modules. I'm not in favor of re-installing them back into the chassis because the damaged module has burnt marks on the pcb. It'll be better to recycle the chassis and power transformer. I can always retrofit it with one of my amplifier kits in future.

(Feb 27, 2017)

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