Checking pot values

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by Aardvark, Dec 24, 2009.

  1. Aardvark

    Aardvark Silver Supporting Member

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    Is there an easy way to check pot values if they are currently installed in a guitar and are not labeled? In this case, they are both push-pull pots. Thanks.
     
  2. GASattack

    GASattack Member

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    You have to disconnect the pickups to check the resistance on the volume pot otherwise you will get the resistance of the pickup as well.

    For the tone pot, I have heard you can use the middle lug and one outside lug, but you will get an incorrect (so incorrect its easy to id) turning the pot to one direction, and get the actual value turning the opposite.

    But, if anyone knows any different, please correct me.

    Ive always done them disconnected from the guitar.

    Kevin
     
  3. mistercoffee1

    mistercoffee1 Member

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    I got this from JohnH at the Les Paul Forum:

    "Set the meter to the 200k resistance range, and connect it across the barrel and tip of a cord plugged normally into the guitar.

    Select the pickup you want to test

    Measure the resistance at full volume, it will be about 6k to 15k, depending on the pickup
    Measure at zero volume - should read zero if you have modern or 50's wiring
    If those check out, adjust the volume to find the maximum reading. It will be 1/4 of the sum of volume pot plus pickup resistance.

    So for a perfect 500k pot, you would expect 125k to 130k. For a 300k pot, youd get 75k to 80k. Actual pots may vary by 20%. These max readings will occur at about 5 with a linear pot and 7 with an audio pot. The tone pots makes no difference."
     
  4. Aardvark

    Aardvark Silver Supporting Member

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    This is interesting. I will have to give it a shot. Thanks!
     

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