scratchy pots on 303

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Mussi81
 
Posts: 98
Joined: Tue Dec 01, 2009 3:22 pm

scratchy pots on 303

Post by Mussi81 »

hi people

can anyone recommend some lubricant/grease etc to use on the pots on a 303? the resonance pot is scratchy and occasionally cuts out the audio completely when turned fully anti clockwise!

thank in advance

Luap
 
Posts: 363
Joined: Wed Jul 08, 2009 7:10 pm

Re: scratchy pots on 303

Post by Luap »

Caig Deoxit is supposedly the best for this. Not tried it myself though.
I used an alternative that I got from BANNED in Germany (because I happened to have an account with them, and was placing an order for some other bits anyway) and it works just great.
http://www.BANNED.de/gb/kontakt_chemie ... tspray.htm

Its fixed all my noisy pots on loads of kit, bar 2 pots on my Deep Bass Nine. So I guess that will want some new pots fitting..

Brassteacher
 
Posts: 248
Joined: Fri Oct 08, 2010 4:49 am

Re: scratchy pots on 303

Post by Brassteacher »

Mussi81 wrote:hi people

can anyone recommend some lubricant/grease etc to use on the pots on a 303? the resonance pot is scratchy and occasionally cuts out the audio completely when turned fully anti clockwise!

thank in advance
Mussi, given the last part of your description, I would test the pot you have before trying to clean/lube it, especially if you use some type of spray. I've worked on many older pieces where the most used area of the resistive element actually gets worn through, to the point that the carbon trace is completely gone in that spot. "Scratchy" is mostly caused by dirt, but sometimes by wear in the carbon trace, but completely cutting out is usually a sign of severe wear. Hook your ohmmeter up to the wiper of the resonance pot, and the pin at the most anti-clockwise position (it's a dual pot, so you'll need to test both sides separately). Start with the knob turned the opposite direction and turn slowly. You should see the resistance gradually change, and smoothly throughout its travel. If at any point the resistance drops significantly, say more than 20% or so, then returns to "normal" a few degrees later, I wouldn't even bother to try to clean it, I'd replace it. A dual, 50K, linear-taper pot is quite common, and it shouldn't be difficult to find a drop-in replacement.

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phono
 
Posts: 1502
Joined: Wed May 02, 2007 4:01 pm

Re: scratchy pots on 303

Post by phono »

this is one the the most common repairs that get sent my way. The best thing to do is replace the resonance pot. Due to the size and depth of the pots they often get pushed downards when tweaking them, this results in the carbon pad being cut in time by the wiper, once they go they are gone and the only option is to replace them.

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