PS Audio 200C Power Amplifier

[kkyee]

My power amp has noise coming out and DC volt output. Can someone circut graph for me to look?

[clm811]

Hi Kkyee,

The amp is over 20 years old, so the on-board electrolytic caps
are probably leaky and need to be replaced.

I would replace those and check the main PS cap bank as well.

The adjustment for DC offset is the trimpot nearest the input jack,
while bias trim is the one near the center of the board.

With good caps, assuming your preamp has no dc coming out, you should be able to adjust the offset with the trimpot.

If not, then I suspect the input transistors may need replacing with a carefully matched pair.

If you need additional assistance, you may wish to contact Rick at Cullen Circuits. I understand that he does service and mods for PS audio products.


Cullen Circuits
2323 Tuley Road
Paso Robles, CA 93446
Tel: 805-237-2113
http://www.cullencircuits.com/

I've attached the only schematic I have, which I believe is for the 200cx.

Good luck with your amp!

-chas

[clm811]

Kkyee!

I found a hand-drawn original schematic of the 200C, attached.

Hope this helps.

-chas

[kkyee]

I don't understand the part of the schematic. refering to the "NPD 5566" The one that is cicled, why is it going into the input from dc servo? between a 10k and the output from the servo. I've changed all the parts already, but at the speaker output, there is also a dc volt out from 0 to 56volts, advancing slowly. Why is this happening? I can't tune the off-set adjust to 0 volt. Thank You

-kkyee

[clm811]

Not sure. I believe mine doesn't have the servo board.
If you need troubleshooting assistance, you may wish to contact Rick at Cullen Circuits (see above).
Good luck with your project.
-chas