How to reduce the pots noisy.

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by renfra, Sep 17, 2006.

  1. renfra

    renfra Member

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    In my BF fender amps the volume and treble pots make scratch when. I cleaned with spry but the problem is still there.
     
  2. brad347

    brad347 Member

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    you need to have somebody check some of your caps for DC leakage.
     
  3. renfra

    renfra Member

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    Can you explain better, I know somebody but he doesn't
    know vintage amps well.
    Thanks
     
  4. brad347

    brad347 Member

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    if someone doesn't know how to check a capacitor for DC leakage, I wouldn't let them anywhere near my amp.

    Potentiometers like to have AC (like audio) going to them. DC (direct current) will make them crackle, even a brand new one. It's a somewhat different sort of crackling than a dirty pot, but similar.

    Check the capacitors immediately connected to the pot for DC leakage. This requires you to unsolder one end of the cap (the side that is nearest the pot) and check for DC voltage on it WRT ground. If there's more than a very slight amount then the cap is bad. The amp has to be running when you do this procedure and it is somewhat dangerous so don't attempt to do it yourself. 4-500 volts live DC = bad hair day.

    It's also possible that your pots are just too far gone and need to be replaced.

    A question.... when you cleaned them, did you open the amp or attempt to spray in through the front? You have to make sure you get the cleaner into the hole on the pot and turn it back and forth a few times to get the gunk out.
     
  5. renfra

    renfra Member

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    I sprayed them when I bought the amps three years ago, unfortunately the first time I used a dry spay, I used the spry without open the amp just through the front removing the konbs . The problem is what kind of spray should I use where I live I can’t find some types you use in USA, and what is the difference between crackling caused by dirty pots?:confused:
    Thanks
     
  6. brad347

    brad347 Member

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    taking the knobs off and spraying through the front will do nothing.

    You need to open that amp up and spray the pots with caig deoxit orsomething similar. Dry spray? You mean like canned air? No. You need a cleaner/lubricant. Also three years is definitely enough time to get pots dirty again.
     
  7. 52ftbuddha

    52ftbuddha Member

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    Cramolin is what you need.
    Rob
     
  8. renfra

    renfra Member

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    I used a spray cleaner which doesn't leave lubrificant, I hope I didn't ruine the pots.
     
  9. Fretts

    Fretts Member

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    I think it will not damage the pots, especially only one time. The worst problem can be if you spray a cleaning solvent into the pot shaft and it dissolves all the grease inside the bushing for the shaft, then you have grease on the carbon resistance track, but the pot does not turn anymore.
    Best to use only a small amount of lubricating cleaner, maybe 1/4 to 1/2 second each, spray into the hole of each pot on the inside of the amplifier and then immediately, operate the one control through the full range of its motion, many times, 10-15 times. Then go to the next pot and clean that one, and then next and next. The combination of cleaner and motion will loosen any dirt and also move it out of the way. I use the edge of my hand, like a saw, to operate the knob quickly all the way from minimum to maximum.
     

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