Peavey Studio Chorus 210

[hbar223]

I have a Peavey Studio Chorus 210 that has no output. I have tested the speakers and they are fine. I pulled the chassis and did not find any burned spots on the board. I was wondering if anyone had any suggestions.

Thank You

[Enzo]

No output.

Ther is a separate power amp for each speaker, so whatever is wwrong is comon to both channels.

Does it light up? DO the speakers thump or pop at turn-on? Any evidence of life? Does the headphones jack work?

Ther are two sets of loop jacks. Plug the guitar into each Power Amp In jack and play. ANy output now? Plug the guitar into the front like always, now connect another cord from each preamp out jack to another amp's input so we can listen to the preamps throough another amp. ANything there?

Check the power suplies. The amps run on about 45 volts - positive and negative. There are four large power transistors, just measure the voltage on the case of each one. Got 45? -45?

If 45s are there, then check for +/-15VDC supplies for the preamp. A couple three leg regilators make the 15s.

No voltages? Check the main fuse, the power switch, the two thermal cutouts, the wiring, the power cord.

[hbar223]

I plugged a patch cord between the output of one and the input of the other, and got clean channel sound with low sound output.

I then plugged in at the front of the amp as normal without a patch cord between the rear pre amps and it produced the same clean channel sound,with low volume.

[hbar223]

I checked the transistors and have 36 volts on each. Any other ideas would be greatly appreciated.

[Enzo]

How about all the other stuff I suggested?

Plug the guitar into each of the power amp in jacks (the FX return jacks), what happens?
Do the speakers pop at turn on?
DO the phones work?
Is ther 15v plus and neg on the op amps?

I am not clear on your response, did you play through the front of this amp like normal and run a cord from each FX sent to a completely different amp for a listen to see what was coming out? Not just patching pre out A to power in B.

[hbar223]

Sorry for the confusing response. I will try it again-

The amp lights up.

There is a thump through the speakers upon turning it on.

I have 14.86-14.92 volts pos and neg through the op amps.

The headphone jack works, although the volume is much less than it should be.

I tried both "in" jacks and I get sound.

Thanks for taking the time to help me out. I am really hoping I can get this Peavey functional.

[Enzo]

And sending the preamp out (FX send) to another amp for a listen results in...?

If you get reasonably strong sound when you plug the guitar into the power amp in jacks, that means the power amps are working - one for each speaker.


which brings us to the preamp. SInce both power channels seem to be affected, I'd look for some stage in the signal path common to both. I don't have the drawings in front of me at the moment, but a weak op amp would do it, so would a broken control or open control. Given that the overall volume is wery weak, do all the controls still seem to do what they are suposed to do? Any that don't?

Look on the output pins of each op amp for DC offset - a few volts, ignore a few millivolts. Apply a steady signal to the input and trace it through teh stages and look for where it diminishes.