Grounding and shielding help

Discussion in 'Pickups & Electronics [BG]' started by BunchyMutt, Aug 20, 2017.


  1. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
    Creating a new thread since this one is getting bloated with different questions.

    I just changed my bass from active to passive, replaced all the switches and pots, and made it have a parallel/single Coil/series switch for each pickup, a three-way pickup selector switch, a master tone, and a master volume. Got everything functional and shielded but noise isn't completely gone, and it's unbearable in single coil mode, which I know is normal to some extent but it's a lot. And in humbucking mode it's not dead silent like I hoped.

    Anything glaringly obvious with my grounding scheme that I should correct before going out and getting a multimeter?
    grounding-scheme-jpg.jpg
     
  2. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    I would try grounding the pickup selector switch.
    Can you touch the metal on the pickup selector switch?
    and does it make extra noise or change the noise level when you touch it?
     
  3. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
    Just tried it. Made a bunch of extra noise.
     
  4. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
    I should add that I touched every other component and no additional noise was added or reduced, fwiw...not sure what the extra noise indicates
     
  5. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    If you have some solder lugs, put one under the switch, after you solder a ground wire to it:

    solder_lug_washer_set__74260.1470693003.500.400.jpg
    unless you can extend the shielding tape under the switch...
    did you shield the cavity to where the switch is?
     
    GentProvocateur likes this.
  6. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
    yup, might not have made contact though. Will try it and report back.
     
  7. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    Ungrounded parts essentially turn into tiny antennas, sucking up RFI.
     
  8. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
    Grounded the switch, and the noise doesn't get louder when I touch it, but extreme buzz persists. I went through and more thoroughly touched the lugs instead of just the pots/switches. Two lugs got louder: terminal one on the tone pot and the jack's middle lug, both of which have nothing soldered to them.

    grounding-scheme-jpg.jpg
    Earlier in all this I experimented with the output lugs - ground to the middle, hot to the middle, etc. Hot is the shortest one, which leaves the other two for ground from the wiring and then from the (no longer installed) battery
     
    Last edited: Aug 20, 2017
  9. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    I think it's pretty standard for the treble cut pot to have one unused lug, but your output jack should only have two lugs.
    You probably have installed the jack for a bass with a preamp. The extra lug is used to activate the battery.
     
  10. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
    Yeah, It's the same jack from when there was a battery and preamp. Does that mean I should ground the third lug?
     
  11. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    I would either change the jack or run a wire over to that middle lug from the ground.
    It shouldn't really be making the noise, but at least if you did that you could then disqualify it.
     
    GentProvocateur likes this.
  12. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
    Thankyouthankyou. I have a few jacks I was hoping would work but I was lazy and didn't get jack's with a long enough barrel
     
    Killed_by_Death likes this.
  13. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
    Jumpered the two grounds together, didn't noticeably change anything. I guess I'm getting a multimeter tomorrow :thumbsup:
     
  14. Make sure your switch selects a north coil from one pickup and a south from the other.

    This will make no difference. The lug will be earthed when you insert a jack anyway. (FWIW, that's how the preamp used to switch on.)

    Are you using tapewounds or elixyrs? Coated strings will stop the string/bridge earth from doing anything.

    Perhaps a few photos may help as well...
     
  15. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
    Thanks. The switches definitely select alternate coils because the buzz is significantly reduced when both are set to single coil and the pup selector is in the middle position.

    Not using any coated strings.

    I'll take photos later today. One thing I didn't do that I'll check is the ground under the bridge.
     
    Last edited: Aug 21, 2017
  16. Third lug on output jack should make no difference.
    I could be wrong on this but depending on how stable your pocket shielding is, maybe you should try grounding straight from the bridge to the output jack. Trusting your shield to be the center point of all your grounding may be a mistake. Is your shielding a solid shield or the shielding paint?
    Are all your solder points totally solid? Solder gun nice and hot? I've seen many cold soldered points lately, mostly from stuff soldered in China.
     
  17. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
    Copper, with solder at various overlap points. I'll try soldering directly to the output jack
     
  18. Ya or just clamp a wire across temporarily. Let me know if it works. Overlapping points should work just as well if you're doing that.
     
  19. Also do you have any other basses that are totally fine? Any strange power issues?
    I have a weird thing where if I point my bass in certain directions it's background noise is louder.
     
    Killed_by_Death likes this.
  20. Do your pickup wires have shielding?
     
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