Carver PM 600 buzzing

[cihtog]

I have a Carver PM 600 that buzzes at the speaker output. If I leave a speaker hooked up to it, it blows the speaker. Before the speaker goes into meltdown, the cone is pushed out toward the listener. Disconnecting the pre-amp circuit from the power circuit within the amp has no effect. The LED meters for both channels on the front panel of the amp are pegged, when I turn off the amp the meters cascade down to zero. The pre-amp section is functional and tests fine, but none of the sound makes it through the amp. The amp is bridgeable at the beginning of the power amp section. Bridging has no effect, the DC at the output is equal in both channels. The amp appears to be amplifying whatever is wrong in the beginning of the circuit. If I disconnect the lower voltage supply from the transformer that supplies the op-amps, it goes back to idle. It has a regulated on-demand power supply with 3 voltage outputs, 22, 46 and 73 volts. The 2 higher voltages are only stable when the lower is disconnected from the amp. The amp appears to be running at full volume with no input and the controls at zero or even disconnected all together. By disconnected, I mean removing the jumpers for adding extra modules between the pre an post sections of the amp. This removes the input section from the chain. I have replaced some suspect components, but it still buzzes. Any ideas?

 

[rockdoctor54]

carver buzzzing

Try looking at this link to Carver manuals, They look like they were written by Bob Carver himself. In Them he talks about sources of buzzing and hum, its a good read but a little technical. One step at a time. At work I usually can Isolate serious problems to somthing simple like a loose or damaged wire.

http://www.carverpro.com/download.html

 

[electricdick]

Carver Buzz

Hi Rock.

Did you ever get your Carver repaired?

If not you may wish to contact the fellows at this board: http://www.carveraudio.com/phpBB2/index.php

Top notch guys and lots of technical support.

D ick

 

[cihtog]

Thanks for the tip on the caveraudio forum, I'm going there right now. I went to carverpro before posting on here and got my manual, thanks though.

I let the amp sit this whole time going over the schematic about a hundred times. I tested and replaced any suspect parts, still the same problem.

I plugged it in today, and it just started working for about 20 minutes until I ran it hard, and one of the caps from the power supply popped. The last time I turned it on before today, it was still doing the buzzing thing, with DC at the output. When I turned it on today, it was crystal clear and worked fine, until the cap popped.