Old Twin Reverb, scratchy pots. Help needed.

Roy Ayres · Post by **Roy Ayres** » 21 Apr 2003 7:13 am

I have a “black face” tube-type Fender Twin Reverb from the 60’s. I recently had the amp repairman in a local music store go through it for purpose of “cleaning it up.” I especially asked him to clean the pots, as they were quite scratchy. The pots are just as bad as before, and I hesitate to take it back to him for a redo – as I’m not sure he really knows what he is doing.

As I recall, the pots are the type with enclosed housings. Is there a way I could clean the pots myself, or do they have to be replaced to eliminate the problem? I would be happy to pay someone locally to do it right, but I really don’t want to have to ship it off to one of the more reputable amp men.

Suggestions would be appreciated.

Gino Iorfida · Post by **Gino Iorfida** » 21 Apr 2003 7:27 am

Well, first thing you could try is with the amp off, rotating each pot through it's full travel about 50-100 times for each pot. if there is any dirt that is in there that is loose, it will knock it out.
If you were to clean it, you'd have to get something like DeOxit or other cleaner for electrical contacts (Lowes, Home Depot etc), you will need to take the chassis out of the amp, and be extremely careful, because even with the amp off, the electrolytic caps in the amp can still hold enough to zap ya good! -- in other words, knowing how to discharge them would be a good move! Use the flexible shaft that comes with the spray, and spray it in the opening inthe pot, near the solder termincals (it's a little slit that allows the terminals to come out) that will let the cleaner get inside... rotate the pot shafts a few tiems and let it all evaporate out, button it back up (DO NOT FORGET TO MAKE SURE YOU PLUG THE SPEAKERS BACK IN!) If that doesn't do it, then your pots will need replaced.
never spray the contact cleaner in around the shaft from the front of the amp, you'll drive out any lubricants there, and cause the pot to freeze up.
Personally, I'd give the guy a call who did the work, he may have totally forgotten to do the pot cleaning -- you'll get a feeling about the guy when you talk to him (in othe rwords, if he admits to his mistake, chances are he's fine to go to... if the starts giving excuses, then beware, he may be lazy or whatever)..

Ricky Littleton · Post by **Ricky Littleton** » 21 Apr 2003 8:08 am

Electro-Wash from Chem-tronics is also a good cleaner.

Ricky

------------------
Emmons LeGrande - 8x4
Session 400 Ltd
Dan-Echo, E-Bow, Ibanez Distortion, Boss Comp./Sustain, Ibanez Auto-Wah

Roy Ayres · Post by **Roy Ayres** » 21 Apr 2003 8:53 am

Gino & Ricky:

Thanks, guys. I'll try the "rotate the shaft" trick this week, and if that doesn't do it, I'll look for one of the cleaners you mentioned and may find time this weekend do the cleaning. I don't think I'll call that repairman, because when I picked the amp up I asked if he had cleaned the pots and he said, "Yes. The only problem you have is that some of the tubes are microphonic and could stand to be replaced." I just don't think he is reliable. I'll do it myself using the methods you described.

Thanks again.

Roy

Ken Fox · Post by **Ken Fox** » 21 Apr 2003 9:41 am

If the tone caps are leaking any DC you will have scratchy pots, no cleaning will get rid of that.

Roy Ayres · Post by **Roy Ayres** » 21 Apr 2003 11:57 am

Ken:

All of the pots are scratchy -- Volume, Reverb, etc. Would leaky caps cause that?

Ken Fox · Post by **Ken Fox** » 21 Apr 2003 12:32 pm

I doubt it. Easy enough to tell, just pull the chassis and make sure you have a load on the speaker jack. Apply power and read from chassis to the pot terminals. If negligable DC and a good cleaner lubricant has been already used, you need to replace the pots.

Scott Jackson · Post by **Scott Jackson** » 21 Apr 2003 7:07 pm

Contact cleaner and rotate the potsmillion times?? Usually works. Maybe some compressed air to get the biggest share out first. I could be wrong, but, in the things I've done it works.
Scott

Scott Jackson · Post by **Scott Jackson** » 21 Apr 2003 7:12 pm

If that doesn't work, I used to use Allen Bradley pots. Heavy duty.Is there something better, guys?
Scott

Roy Ayres · Post by **Roy Ayres** » 22 Apr 2003 8:42 am

Thanks to all of you. Most of your suggestions are along the same line: us a good cleaner and rotate, rotate, rotate. Thanks also to those who sent me personal emails. I plan to order s can of the DEOXIT and play around with it. If that doesn't work, it will be clear theat I need new pots -- so, thanks, Scott, for pointing me toward the Allen Bradley pots. In my day (olden times) Ohmite were the preferred pots -- but I understand they are no longer available.