Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Esquirefreak on November 09, 2023, 08:53:32 pm
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Since new stuff is crazy expensive here in Sweden, due to currency exchange rate, I'm trying to build with what I've already got on hand.
I have a big box of old potentiometers that I bought for cheap a couple of years ago. Really nice ones from Clarostat, ESA, Colvern and others. Many of them are wire wound.
Some of them are stiff to turn, not scratchy or stuck, they just require more torque. My best guess is due to dried up grease.
My question;
Has anyone of you a good way of servicing old pots?
/Max
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I just spray the insides with contact cleaner, and then work them. Seems to work well most of the time.
When I think of it, I use Caig Deoxit Pot and Switch cleaner. But mostly I just use whatever I have around the shop (ie, cheap stuff).
Years ago I could get repair kits for some pots, but haven't seen these in a long time.
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DeOxit or CRC
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I'll give it a try. Thanks!
/Max
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If they are very stick, try using a dry spray cleaner then use WD-40, if they aren't very stick try only with WD-40
Franco
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Has anyone of you a good way of servicing old pots?
I need to ask Jeff Gehring on another forum. Or perhaps PRR or pdf64 on this forum has done this?
I know Jeff sometimes will disassemble an old pot, clean the track, re-tension the wiper, and apply some lubricating grease if needed. This is done for old amps with old pots made to a high standard of quality, where it is desired to maintain the originality of the amp (to retain collector value), and where it's okay to spend the extra time. The the pot shell is re-attached around the pot body, and installed in the amp.
According to Jeff, most older amps with scratchy pots that aren't cured by a shot of contact cleaner don't need to be replaced. However, a tech's time is $$ for the amp-owner, and it's faster to just swap out a pot. The equation changes when you're talking about a 1956 Strat, where the modern pot reduces the guitar's value by $$$$$$$$.
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Yeah, in the box I found some dual gang 100k pots, with a SPST switch at one end of the track. It has massive casted (!) casings, pretty sure its zink. Built to last, to say the least! Nothing is built like that anymore.
I'll upload some photos during the weekend. Think I'll try to figure out the date on some of the as well, as I think they might be pretty old.
Thanks, everyone who chimes in!
/Max
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Nothing is built like that anymore.
Yes nowadays things are done in a way less quality
give a look to this old italian Geloso pot
the wiper is a piece of plastic that slides on a brass arch
so there is never a rubbing between the wiper and the trace of carbon
only the brass bow is pressed (without rubbing) until it is in contact with the desired point of the trace
Franco