Volume Pot Noise

[jimsz]

My Weber SuperReverb clone has been working great for some months now but seems to have developed another problem. It's got similar static noise as before but now when I remove the second tube (12AX7) that connects to the "second" volume pot (pin 7), it screeches very loudly. The screech can be turned off with the "first" volume pot and comes on right away at about 1 on the setting and gets worse as you dime it over.

Plug the tube back in and its fine except for the usual static noise. Very odd, indeed. I tried re-soldering some of the points in the circuit but it doesn't seem to change much.

[M Fowler]

Try retensioning the tube socket pin holders they may have become loose.

Mark

[jimsz]

Try retensioning the tube socket pin holders they may have become loose.

Mark

Interesting Mark, when I shine a bright light from the inside of the chassis through the tube socket, the light shines through all the holes except pin hole #2 which looks completely blocked. Does this socket need replacing? I can't seem to unblock with it anything small enough.

[M Fowler]

It must just be solder that has dripped down there, which is a common occurance. Heat the pin and remove the solder. I use a very small flat blade screw driver to tighten the socket.

But you probably already tried different tubes but in case you didn't, use a different tube to test this position since the amp was working well and now has static.

[M Fowler]

Forgot about that volume pot. Is the pot of poor quality it maybe have gone bad. Chop stick around the volume pot area.

[jimsz]

Forgot about that volume pot. Is the pot of poor quality it maybe have gone bad. Chop stick around the volume pot area.

When I push on the middle pot tab of volume 1, it makes loud popping noises. Moving it slightly produces the static noise, even after I re-soldered all the connections.

Is this pot hooped?

[bluesfendermanblues]

Forgot about that volume pot. Is the pot of poor quality it maybe have gone bad. Chop stick around the volume pot area.

When I push on the middle pot tab of volume 1, it makes loud popping noises. Moving it slightly produces the static noise, even after I re-soldered all the connections.

Is this pot hooped?

If it's an alpha pot? Then yes probably. Alpha pots sound fine, but dont like to be solderd too much.

[Kregg]

The same type of thing happened to me once. It turned out that I completely missed adding one of the ground wires, and that was after I checked and double checked the schematic.

[M Fowler]

Well pushing a pot around is probably going to result in noise even on a good pot as the carbon track is being moved.

It would be beneficial to start from the beginning as suggested and carefully go over everything especially grounding. This has happened to all of us at one time or another where we missed something even after we went throught the amp several times.

Mark

[jimsz]

If it's an alpha pot? Then yes probably. Alpha pots sound fine, but dont like to be solderd too much.

It doesn't look like they are Alpha pots. Some who purchase the Weber kits will upgrade to Alpha or CTS, but others feel the pots that come with the kits are fine. I think they are fine as they seem to turn easy, not much friction.

[jimsz]

The same type of thing happened to me once. It turned out that I completely missed adding one of the ground wires, and that was after I checked and double checked the schematic.

I'll check that again, but the amp seems to have been working fine for quite a while. I have run across a few cold solder points and have also been re-soldering some of the points around the pots, switches and grounding.

[jimsz]

Well pushing a pot around is probably going to result in noise even on a good pot as the carbon track is being moved.

It would be beneficial to start from the beginning as suggested and carefully go over everything especially grounding. This has happened to all of us at one time or another where we missed something even after we went throught the amp several times.

Mark

Will keep at it, Mark before replacing that pot. I tried pushing in the same way on the other pot tabs as well as the second volume pot but none of them made any noise at all, just the first volume pot.

I've also been working on the tube socket, removing all the solder from that pin and redoing it. Also, have been trying different tubes and moving them around. It sure is difficult to know if a tube has gone south or not when the problem persists.

If the tube had a problem, why would I get that screeching nois only when I removed the second tube? That never happened before.

[M Fowler]

Yeah it sounds as though step one should be replace the volume pot and go from there, hopefully that will be the source of the problem.

[jimsz]

Picked up a new CTS pot, installed it and let the amp burn for several hours, played it for another hour last night and it's dead quiet. No screeching when the tube was out, again, dead quiet.

I noticed the other volume pot was replaced with a CTS as well and when I thought about it, I remembered it was an out of box failure, so both volume pots were bad.

Thanks for help, Mark. Much appreciated.

[M Fowler]

Glad you got your amp back up running good job.

Mark