How do you test a control pot?

Discussion in 'Pickups & Electronics [BG]' started by rabid_granny, Mar 25, 2004.

  1. My Jazz Bass crapped out on me again. The neck pickup works but the bridge pickup emits no sound. This happened before so I replaced the bridge control pot and it worked.

    I want to check to see if the control pots are working and perhaps there is another defective element. Are there any tests I can perform on the control pot? My bass is a Fender American Standard Jazz Bass.
  2. Mattski


    Jan 6, 2003
    Cleveland, OH
    You could do it with a multi-meter. A control pot is just a variable resistor. When it's full open, there should be no resistance. As you close it you would see the resistance increase to infinity.

  3. using a multimeter that can measure resistance:

    note: i'm assuming you have the shaft pointing up and the terminals pointed towards you

    1) turn the knob all the way to the left (counter-clockwise) and place one test lead on the left terminal and the other one the middle (this should give you no resistance)

    2) turn the knob all the way to the right (clockwise) and place one test lead on the right terminal and the other on the middle (this should give you no resistance)

    placing the leads on the outer terminals should give you the full resistance value of the pot (or close to it..i cant ever seem to get the EXACT value)
  4. I work with electronics all day and have yet to see a resistor that reads the EXACT value even straight out of the box. It's always going to be a few ohms off. It's just because they're mass produced and not perfect.
  5. Okay! I tried the test today and the results were almost exactly as described. The only thing was that when I was supposed to get zero resistance, there was a tiny little bit.

    So what does this mean? A pickup and control system is pretty simple so does this mean my bridge pickup has failed? Or is there a loose wire connected to my bridge pickup?
  6. Tim__x


    Aug 13, 2002
    Alberta, Canada
    That's just fine, as long as it's less than a few hundred ohms it's good.
  7. I'd think that a loose wire is more likely than the pickup failing. Check for loose wires and make sure everything is connected good. If your still not sure if it's the pickup, you could always put the pickup in another bass and see if it works.

  8. you could also try wiring it directly to the output jack and bypass your electronics.. this will give you a good idea about whats causing the problem
  9. Get this. I checked all of the wiring and it was solid. So I replaced the bridge pickup control pot with the original pot (which I thought was defective), resoldered the connections and it works again. If anything, my soldering job was worse than the factory job but hey, it's working again and I'm happy.

    Thanks to everyone for helping out. The voltmeter test was something new to me.