Musicman RP-65 (2165-RP) distorted sound, even at low volumes

[Gerhard Grass]

Hi to all,

I have here a Musicman PR-65 witch came to me, because it sounds distorted,
even at low volumes.
Replaced the power tubes -> no change
replaced to filter caps -> no change (inspite of the fact, that the amp seems to have more punch with the new tubes and co's)
Checked the voltage over the filter caps -> seems to be o.k. Switching between Hi/Low Output seems to work too.

The sound of the amp be best described as distorted like a bad lead sound.
Seems to get a bit worse, when the amp is warm.

Really would like to bring the beast back to life.

So any help and hint is very much appreciated.

Thx in advance!

Greetings from Vienna/Austria/Europe

Gerhard

[52 Bill]

I have here a Musicman PR-65 witch came to me, because it sounds distorted, even at low volumes.

There so many causes of this type of problem that you need to try and isolate where the problem is happening.

If you insert a stereo plug into the hi level loop jack on the front panel, you can send a signal from the preamp to another amp and see if the distortion is being generated there. The ring contact is the preamp out.

If you send a signal into the power amp, you can see if the distortion is being caused by the power amp circuit. The tip contact is the input to the power amp.

Once you know where the distortion is being created, you can start to measure voltages to try and find the cause.

[Enzo]

Check the schematic, and start by checking the voltages on the pins of the power tubes.

[Gerhard Grass]

Thanks to all for help,

amp is up and running again.
After all it was a bad solder joint on one of the cathode-transistors

greetings Gerhard