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Thread: Tone pot buzz

  1. #1

    Default Tone pot buzz

    I recently changed out the pots on my gibson mandolin. I'm getting a slight buzz when the tone control is wide open (treble), but if I touch the knob the buzz goes away. Also, if I turn the knob the other direction (bass), it goes away. I'm thinking ground, but not sure where to begin. Any help is appreciated. I've included a pic of wiring.
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    Last edited by Titleist77; Aug-02-2017 at 11:41am.

  2. #2
    Registered User rockies's Avatar
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    Default Re: Tone pot buzz

    By your description it sounds to me that the wiper inside the pot is riding up at the extreme end of rotation and losing contact with the resistive element. Usually the detent in the pot cover stops it from rotating that far. If you just rotate back slightly and problem disappears that may be the problem. Pot replacement or if you're experienced enough remove the pot, remove cover (little tabs) and see if you can correct the problem, loose wiper or spring tension etc. Hope that helps
    Dave
    Heiden A, '52 Martin D-18, Taylor 510, Carlson Custom A with Electronics

  3. #3

    Default Re: Tone pot buzz

    Thanks for the reply.

    I had another set of tone/volume pots and switched them out. Still same result of buzz unless you roll treble pot to bass side or I touch either volume or tone knobs....
    Last edited by Titleist77; Aug-02-2017 at 1:49pm.

  4. #4

    Default Re: Tone pot buzz

    Here's another pic:
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  5. #5
    Registered User Tom Wright's Avatar
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    Default Re: Tone pot buzz

    You could run a ground to the tailpiece if the strings are not grounded. The wiring looks good but without a shielded cavity or shielded wires it looks like it invites hum. Perhaps there was a string ground and you dislodged it? I grounded my Fender FM-52E by looping an E string around the underside of the output jack and tucking it under the tailpiece plate.
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  6. #6

    Default Re: Tone pot buzz

    I went straight from the pickup to the output jack and the hum is still there. I put everything back together and soldier a wire to back of tone pot. Try I g to find a place to ground it and see if that helps. I may look in that tailpiece area.

  7. #7

    Default Re: Tone pot buzz

    It looks like you might have a ground loop in the wiring. Ground loops cause hum and will often occur when using the chassis of the pots as grounding points.

    Best way to eliminate ground loops is to use a 'star' ground wiring technique (google is your friend). That involves taking everything that is supposed to go to ground to a single ground point.

    I solder all grounds to a washer then wrap it with electrical tape. It requires a bit more wire but provides a much cleaner signal path.
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  8. #8

    Default Re: Tone pot buzz

    Quote Originally Posted by Titleist77 View Post
    I recently changed out the pots on my gibson mandolin. I'm getting a slight buzz when the tone control is wide open (treble), but if I touch the knob the buzz goes away. Also, if I turn the knob the other direction (bass), it goes away. I'm thinking ground, but not sure where to begin. Any help is appreciated. I've included a pic of wiring.
    Is the tailpiece still grounded? The strings need to go to ground as well and that's done by a wire between the tailpiece and your ground point (if it's a normal guitar-type pickup). That wire can sometimes break loose when you're doing other work, so you might want to check that nothing came undone.
    VerneAndru.com | oKee.ComX

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