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Stuck contrast / brightness knobs on my model 3

mrthreeplates

Experienced Member
Joined
Jul 22, 2018
Messages
77
I know there are lots of threads on this common issue, but I've only read one where it was mentioned that you can take the pots apart.

While it looks like I can find these pots new, I wanted to see if I could fix mine properly and permanently.

I took some pictures just to show it can be done.

My procedure:

Take the back off the pots by carefully prying back the locking tabs.

One of the pots (500k ohm) can come completely apart, so it was easy to clean. Fortunately, this was the really gummed up one. I cleaned the shaft with 99% alcohol and used deoxit on the contact wiper. After drying and checking the resistance, I put it back together.

The other pot (500 ohm) was pressed together so I couldn't remove the shaft. However, by slowly working alcohol into it I am fairly certain that I've gotten most of the gummed up material. This took a while as I wanted to be sure.

I then reassembled the pots and put a tiny drop of Teflon dry lube on shafts. I worked this in a bit and both pots are totally free now.

I'll see how it is in a week or so, hopefully the stickiness doesn't return. I'll report back if there are any problems.
 

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I'm not following this--I've got pots that are at least 50 years old (probably older) and have never had to take any of them apart. Just some contact cleaner squirted into the housing near the terminals, and working the control back and forth.

About the only time I've had to take one apart was in a pinch, where the resistive track arced and developed a dead spot. I could repair that one temporarily with a soft pencil.

What was it about yours that necessitated disassembling them?
 
More than likely he wanted a challenge ---- if one feels comfortable doing it ---- then why not --- I just replace the pots with new ones --- maybe I will try dis-assembly in the near future.

Hope they resolve and work well for you
 
As to why I did this, both pots were gummed up. However, one was stuck so bad I had to use a wrench to turn it.

Without really getting the dried up lube out, I figured the stickiness would return once any solvent I used dried up.

Also, without taking the back off I was concerned that the old lube would be washed up on the contact pad. Then I'd have to flush it more. Yes, I know, I'm probably over thinking it.

It just seemed better to take them apart to really clean it. It wasn't hard and was interesting to learn how the two different pots worked. I only think the metal tabs will take disassembly once before breaking. With the deep cleaning they got, I don't think they'll seize again.

Besides, if I broke them, I would be no worse off.
 
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