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OK people...I have a grounding problem.

Discussion in 'Hardware, Setup & Repair [BG]' started by PanteraFan, May 15, 2001.

  1. OK. My strings, they pop when I touch them. But, only when my Tone pot is at full(my bass is 2 vol, 1 tone). As long as my Tone pot is at nothing there is no other popping no matter how I arrange my 2 vols(P pickup, J pickup)

    Could any of you guys tell me how to fix this problem(isolated, I believe, to my Tone pot)

    Thanx and keep headbanging.
  2. Suburban


    Jan 15, 2001
    lower mid Sweden
    Check the ground wire to your bridge, for starters.
    If that's OK, check the pot and capacitor and all the connections there.
    Third step: resolder everything!

    Oh, BTW,,,,are you sure it's the axe? Or could it be your head bangin' into something? :D
  3. I was actually hoping for a little explanation of why I was getting the popping and why it is isolated to my tone control(surely another pot could be ground to my bridge)? Not just some directions that I couldnt troubleshoot or understand what I was doing with them if they didnt work.

    Check the pot? What, look at it? Resolder it? Use a multimeter on it? Shout at it till it works?

  4. Rumblin' Man

    Rumblin' Man Banned

    Apr 27, 2000
    Route 66
    If you feel you can't handle the problem, take it to a tech.
  5. Suburban


    Jan 15, 2001
    lower mid Sweden
    I think you should consider a tech. If you're not familiar with electronics, I fear that is the way to go.
    Otherwise, checking elec's include magnifying glass to check solders, ohm meter to check what you can't see, and a lot of imagination to invent new ways to check things :)
    Most axes seem to have the ground of the pot as some kind of collecting point, where most ground wires come together, and just one gruond to the jack.

    But I think you could do very well with a one to one talk with a tech. Maybe look over his shoulder?!
  6. If you've got a multimeter set it to the Ohms range. Remove the bass from the amp and unplug the jack lead. Clip one multimeter lead onto the bridge and one onto each string in turn. On clipping to each string you should see the meter needle (or digits if it's a DMM) show zero ohms. That checks the strings to bridge continuity.

    If that's OK clip one multimeter lead onto a (any) string and plug the jack lead into the bass only. Clip the m/m lead onto the barrel of the jack plug on the other end of the guitar lead. Again you should see zero ohms. Wiggle the guitar lead around in the jack skt on the bass (gently) to see if the m/m reading changes from zero ohms. If not then OK.

    If you've got metal control knobs on the bass try thr m/m between strings or bridge to the knobs. It should read zero ohms.

    If that's all OK then it's time to remove the control plate / scratch guard and delve inside.

    That's perhaps the time to go to the Tech if you're not confident from there on.

    Hope that helps.

    Rockin John
  7. I'm determined to fix this myself, and there has been a new development - when i touch my bridge, there is a popping sound too. Ditto for my tuners. However, my control knobs do not pop. The popping is still isolated to when my tone control is at anything but zero.

    What does this mean then fellas?

  8. leftybassdog

    leftybassdog Senior Supporting Member

    your ground wire to the bridge may be open or lost its ground, open the back of your bass and you will see a wire with no insulation on it and it should run to the bridge the wire sits under the bridge, if the pot turned the wire might have a break in it, to check it look and see if you see a break, if not pull on it but not hard just to feel if it moves easy and starts to pull out, if so the wire will need to be replaced, if not remove the bridge and clean were the wire is or wrap the wire around a screw under the bridge and replace it.
  9. The ground connection to the bridge is probably fine. There is something going on at the amp or plug. When you touch the strings and it goes away, you are connecting your body to the circuit ground. The fact that the tone control does what it does is normal. The popping is coming from an external electric noise source. On old amps, there was a Polarity switch, and if you had popping, you flipped the switch and it went away. In some cases, it will still be there to some degree because the noise is being induced in your body by external fields. Fluorescent lights nearby? Power substation next door? Industrial places on the same power grid as you? Any of this and other stuff will cause there to be noise into the amp.

    Or it could be an amp problem.:)

    First round of tests: Try the amp and bass in a different location, like someone else's house, or a music store. It's even better if you can have another location with a different bass and amp. Then you can mix and match and see where the problem stays. That will isolate it.

    I suspect that in another location, all will be fine.

    As it was in this thread:

  10. So you're saying that my amp is the problem?

    Well, the problem is that I plugged my Bass direct into my stereo(using a phono to jack lead), and it still popped.

    I'll try it on another amp. I have thought it was the amp, as it is a guitar amp and not a bass one(I'm not that rich).

    I will conduct further tests!
  11. PanteraFan.

    You must approach the solving of this problem in a logical fashion.:D That's how electronic fault diagnosis is done - should be done!!! - and you appear to have an electronic fault. Without soundine overbearing about it, check-out 1 piece at a time and either eliminate it or confirm it as faulty. And please be aware that there might be more than 1 fault existing at any one time.

    So, did you follow my suggestion about checking the earth continuity of the strings / bridge / guitar cable? If so what were your conclusions: did it check out properly or not? If it was OK then it's time to move on to the next stage.

    Let me know.

    It's genuinely great that you want to try to bottom this yourself. Please, though, be aware that your personal safety could be compromised if you don't get grounding difficulties sorted properly (and you appear to have a grounding difficulty).

    The most likely reason that the control pots don't pop is that (assuming the knobs are metal) the pots are probably fitted with shafte made of an insulating material, Eg.Nylon.

    Please check this problem through in an orderly and systematic fashion. You're likely to get the result more quickly like that.


    Rockin John
  12. :DErr, sorry about the typo errors in above. Will try to be more careful / spell check in future.....:D

  13. You see, the last chance I had to use a multimeter was when I was in school. And I've, well, left school now.

    I'll take the knobs off the pots and try that.
  14. I did it. The pots pop.
  15. Just to be clear...you're saying that when you touch the metalwork of the pot body (eg. the fixing nut) you get the popping?
  16. JohnL


    Sep 20, 2000
    Grayson, GA
    One MORE thing to confuse matters more. A lot of basses have a bare ground wire running under the bridge, and even though the wire may be clean and unbroken, I have seen a case where the bridge screwed down on top of the ground wire pushed the wire deeper into the finish, where it would intermittently lose contact with the bridge, causing a ground(less) hum.
  17. That's certainly correct. That's why I was hoping PanteraFan could do a multimeter test: it'd save having to strip the bass.

    If that's what turns out to be wrong with his bass, I've cured that problem before by soldering the connection wire to a piece of brass or copper shim to vastly increase the possible area of contact, then screwing the bridge down onto it. I've also cleaned the underside of bridges with wire wool then smeared some silicon grease onto that area to attept to reduce further oxidization.

  18. Yeah, the actually variable resistors in the cavity pop.

    BUT! I tried the bass at my school on the bass amp. No popping, not matter how much I messed with the controls on the amp.

    Maybe my amp isn't grounded properly? No problem, it's not mine, it's a guitar amp, and it's gonna be replaced by a bass amp this year.
  19. Cool! Now we're getting somewhere. Sounds like your bass is not the culprit.


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