Mike Sweeney
Well-Known Member
So I replaced a very hard to find balance control on my 2285B and decide to explore the old one. It didnt work well, the right side would cut out and all kinds of noise when turned even after DeOxit, cleaner and Shield.
What I found was you could see the ohms resistance jump around when you rotated the shaft but it didn't short out or zero out so I figured that the pot was at a basic level, working. So I took apart the top cover and I found not just the wiper that I expected, but these pots only half of the resistance path is used. The other half is coated. I also found an UPPER wiper that never would get cleaned regardless of how much spray one used unless you turned the unit upside down and then soaked it. And that would be a maybe.
I took a couple of foam cleaners with some IPA and scrubbed the upper assembly after I took it apart. Then on the lower which I'm not sure how to take that apart, I went with a small scrubber and used a relay burnishing tool on the contacts. rinsed everything with an electronic cleaner and now the measured resistant is rock solid and smooth without the noise and jumping around. I need to work out how to fasten the top wiper assembly back on.. probably some 12 hour epoxy will do the trick.
But I feel pretty confident that I could reassemble this pot and have it work well again in a unit.
What I found was you could see the ohms resistance jump around when you rotated the shaft but it didn't short out or zero out so I figured that the pot was at a basic level, working. So I took apart the top cover and I found not just the wiper that I expected, but these pots only half of the resistance path is used. The other half is coated. I also found an UPPER wiper that never would get cleaned regardless of how much spray one used unless you turned the unit upside down and then soaked it. And that would be a maybe.
I took a couple of foam cleaners with some IPA and scrubbed the upper assembly after I took it apart. Then on the lower which I'm not sure how to take that apart, I went with a small scrubber and used a relay burnishing tool on the contacts. rinsed everything with an electronic cleaner and now the measured resistant is rock solid and smooth without the noise and jumping around. I need to work out how to fasten the top wiper assembly back on.. probably some 12 hour epoxy will do the trick.
But I feel pretty confident that I could reassemble this pot and have it work well again in a unit.
