The Steel Guitar Forum

I am sure this amp never saw a cover before I bought it. I have cleaned the pots a few times with Radio Shack electronic cleaner/lubricant. They clean up for a while, but the problem returns. The main offenders are the volume, treble and reverb knobs.
The reverb will prduce a background distortion that disappears when I turn it to zero.
I would please like cleaner suggestions.
Also it may be time to replace these pots. I wanted to keep it as original as possible, but if the pots cannot be cleaned up I will replace them.
Where is the best place to buy quality replacements?
Thanks ahead of time.
regards,
Lefty

Caig DeOxit D5. My local Radio Shack even has that, but it's widely available, google search will yield many suppliers. Even many guitar stores sell it, Elderly Instruments, for example.

Personally, I would never change a pot in a valuable vintage amp unless it was somehow damaged or otherwise not working and not fixable. Changing pots definitely hurts their value, and unless absolutely necessary, I would persist trying to fix it.

I've never seen a pot that couldn't be fixed unless it was physically damaged or completely frozen in-place - and sometimes even those can be fixed. If it basically works, I've never had to replace one. These aren't like the pots in a volume pedal which get turned constantly. Since this one cleans up, I suspect that you may need to be a bit more aggressive on cleaning. I've used the Radio Shack cleaner, it's generally been OK - but I think DeOxit D5 is the gold standard. Don't be skimpy - if I have an intransigent pot, I dump a lot of cleaner in it and continue turning back and forth well past the point where I don't hear problems. If there's a lot of oxidation, it may require several cleanings to get rid of it.

When normal cleaning - spray DeOxit and turn back and forth a bunch of times to clean up oxidation - doesn't work, it may be possible to take apart an old pot and restore. Probably best done by someone who's done it many times before, it requires knowledge and patience.

My take, YMMV.

PS - are you sure the reverb noise is caused by a dirty pot? Lots of things can cause that.

Dave,
Thanks for your input. I did change the reverb driver tubes thinking that was the problem but it appears to be the pot.
I will try the other cleaner.
regards,
Lefty

That's a nice amp. If it's distortion you are hearing, it's probably not the pot. You changed the driver tube, try changing the reverb recovery tube (fourth from right looking from rear of amp). It should be a 12AX7.

Raybob

Here's a trick for replacing pots but keeping the integrity of the amp. Unless it's a sealed pot, the pot should have four tabs on one side that will allow you to remove the cover. After the cover is removed, you can then swap out the original carbon wafer (black ring) with the wafer out of a new, identical pot. Close it back up and you have a new "old" pot. Here's good article that will help:
http://www.geofex.com/article_folders/p ... tscret.htm
It's effects pedal based, but the principle is the same.

As for the distortion with the Reverb: What kind of distortion is it? If it is "musical", I would check for drifting plate and cathode resistor values on the Reverb recovery tube. You can also try replacing it as previously suggested. If it is not musical, you may have a leaky bypass cap that is leaking a little DC voltage onto the pot and thus the grid of the next stage.


oh yeah, "ditto" on the DeOxit D5. You may also consider using a seperate lubricant too. Caig makes it as well.

A new set of preamp tubes seemed to have fixed this problem. The pot noise is still there until I can do a good cleaning, but I can live with that as long as it is not there when I am playing.
Thanks for all the feedback.
Lefty