Re: Need Advice on Repair of Peavey Standard 130 Watt Power Amplifier


"Dr RaTsTaR" <DrRaTsTar@xxxxxxxxxxx> wrote in message
news:j2a7h3llc7sq7ff3r4n1vim1h1ed6t8b5h@xxxxxxxxxx
Hello,

I am attempting to repair a Peavey Standard 130 watt power module and
would appreciate some advice. I am not experienced in amplifier or
electronics repair but I have taken all the electronics courses that
the local Jr College (Mesa Jr. College, San Diego) had to offer. I
have a lot of theory but not any practical experience.

The amplifier will pass a music signal to the speaker when I patch an
audio signal directly into it, but the music is cracked and fuzzy,
very distorted. Here we have bypassed the pre-amp front end
completely. This unit is in a Standard Power Pak, which is a guitar
setup.

I have the schematics and have been poking around with a computer
sound card oscilloscope (Daqarta). I have also constructed a simple
tone generator so that I can use a stable signal to trace.

What problems might allow a simple amplifier like this to still work
even though it is distorting the signal? I have checked the main power
transistors in circuit using a diode checker on my Beckman DMM.

I recently successfully repaired a Peavey XR600E using this same diode
checker to identify the 3 blown transistors in the left side. I also
had the right channel to compare readings to, so that was a great
help.

Any help you can provide would be greatly appreciated.

Thank you.

d0ct0r RaTsTaR

Scope the output where the speaker would connect while feeding a tone into
the amp and see what the distortion looks like. That can give you valuable
clues.


.

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