Peavy Bravo Revisted

[unclej]

two or three weeks ago i posted the following thread. yesterday i got the amp back and it's doing the same thing.

"the symptom: after this little peavey, a bravo 112, warms up it begins to make a sound like feedback only it isn't. it's a low pitch sound..approximtely a low g on a guitar. it does it with all the volume knobs tuned down. it's volume can be controlled only with the reverb control knob and once it starts it increases in volume by itself until it's too loud to stand. it does not seem to start on it's own but after a few minutes of warming up it will start once i pluck a string on the guitar. i know it's not feedback because once it starts it continues even after i unplug the guitar.

troubleshooting so far: i've checked the electrolytics and replaced all of the tubes one at a time with known good ones to no avail. i've tested and cleaned all of the control pots and they seem to be functioning properley. before i started checking resistors and such i thought i'd see if one of you might have experienced the same thing and whether or not you think it could be a symptom of a bad reverb can."

when it was in the first time i replaced all the tubes, checked all of the electrolitics, checked the wires from the can (though i may replace them today just to be sure) and burnt some sage over it just to be safe.

the owner of the amp told me that this was the second can that he had put into it. the one that came with it was bad, the one he had installed broke a spring and now this one. he said it was out of a fender amp of some sort but that the guy who sold it to him said it had the same specs.

so my question again is could this problem be caused by the reverb unit going bad? one of the transformers perhaps? i don't have any spares here to trade out and i'd hate to have him pay for another one if that's not it but i've run out of ideas.

thanks again

johnny

[JoeAArthur]

I'd want some verification that the Fender reverb tank did indeed have the same specs as the original Peavey.

Sometimes, if they get bounced around enough, the inside "tray" that holds the springs can get thrown up over the locator pin that normally tries to prevent excess movement. This will cause a solid mechanical connection with the outside of the unit which shouldn't exist and can cause feedback problems because the vibrations are more easily transferred to the inside tray. Check this out by inspecting the inside of the unit. You should see the two pins and they should be centered in two round holes cut into the center of the tray.

Also make sure the springs that float the tray at both ends haven't been stretched out of shape.

[spazzyone]

just unhook the pan

if it goes away then thats your problem

[unclej]

I'd want some verification that the Fender reverb tank did indeed have the same specs as the original Peavey.

Sometimes, if they get bounced around enough, the inside "tray" that holds the springs can get thrown up over the locator pin that normally tries to prevent excess movement. This will cause a solid mechanical connection with the outside of the unit which shouldn't exist and can cause feedback problems because the vibrations are more easily transferred to the inside tray. Check this out by inspecting the inside of the unit. You should see the two pins and they should be centered in two round holes cut into the center of the tray.

Also make sure the springs that float the tray at both ends haven't been stretched out of shape.

i'll check that out monday..thanks