Please help with electrical "pop" and static sound

Discussion in 'Pickups & Electronics [BG]' started by jakelly, Aug 9, 2013.


  1. jakelly

    jakelly

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    Gibson Thunderbird.

    When I lift my left hand fingers off the strings, like to go to a higher position, and then retouch the strings, I get an audible and annoying electrical "pop" sound and maybe some static at times also.

    The strings are grounded because when I touch the bridge the 60 cycle hum or whatever it is, lessens, and the bass idles more quietly.

    Is it possible that the bridge ground wire (goes to a post for the 3-point bridge) isn't getting solid enough contact?
     
  2. VanillaThundah

    VanillaThundah VERY enthusiastic walks... Supporting Member

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    Could be a shielding issue. Might want to line the pickup and control cavity with some copper sheets to alleviate it.
     
  3. jakelly

    jakelly

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    Shielding eh? I thought shielding wasn't as necessary with humbuckers, but I'm probably wrong. There is no shielding at all in the control cavity, not even shielding paint, and I assume no shielding under the pickups.

    I checked ground continuity just now with my DVM, and that is fine. From the nut on the output jack to a string has good continuity, so I don't think its a string grounding issue. That means the bridge ground wire is OK.
     
  4. llldino

    llldino

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    sounds like the capacitor is discharging. what is your tone level at when you hear the pop? do you have a multi so you can check if the capacitor is grounded? i'm not too familiar with gibson wiring schemes. definitely sounds like a grounding issue somewhere. if it was a shielding issue you would hear static all the time, which goes away when your hands are on the strings.
     
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  6. jakelly

    jakelly

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    I have a multi but don't know how to check a capacitor.

    When the the tone control is turned down (less bright) the pop pretty much goes away. When turned all the way the other direction (brightest sounding) the pop and static is pronounced.
     
  7. llldino

    llldino

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    yeah that makes sense, essentially the capacitor is filtering out the sounds that you're hearing, meaning that it is grounded properly.

    like I said, i'm not too familiar with gibson wiring circuts, i wish i could be of more help. if you want to try and figure it out yourself, open it up and take a look at the connections. a good solder joint will be shiny silver and completely cover the wire that it is connecting. a bad solder joint will be funny looking, or have a dull grey almost white coat on it. I would go nuts with the multi and check the resistance on all connections, see if you can find one thats loose or frayed looking.
     
  8. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Gold Supporting Member

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    It is static electricity build up (at least that is what I have been told).

    If you give your bass a proper shielding job it will go away, I assure with 100% certainty as I have seen the issue before.

    If you need to know how to do a shielding job PM me if you cannot find anything, there are plenty of resources on here but I am glad to help.
     
  9. jakelly

    jakelly

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    Thank you for the info. I wondered about static electricity maybe causing this. I have shielded a few basses before, so I can do it. Although it is time consuming. Do you think I have to do the pickup cavities too, or will just doing the control cavity make a huge difference?
     
  10. llldino

    llldino

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    yes, shielding the pickup cavities is just as important as shielding the control cavities. make sure you get the underside of your pick-guard too! you basically want to create an enclosed container of copper that all connects to ground (sleeve of your jack)
     
  11. jakelly

    jakelly

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    OK, can do, but only one of the pickups is surrounded by the pickguard.

    About the pickup cavities... most factory shielding only has the brass plate at the bottom of the cavity. The only way to improve on that is doing the sides of the cavity (and underside of pickguard if appropriate), but it seems that's not gaining much with plastic covers on the pickups.
     
  12. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Gold Supporting Member

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    The brass slips in the bottom of the cavity don't do **** in my experience, I usually take them out and copper foil the pickup cavity and then put them back just so I don't throw them out, if a bass has them.

    You need to do the pickup cavities, including the sides, and you should also be doing the pickup covers themselves. I like to bring the copper foil around to the side of the pickup covers so I can solder a wire to the outer edge, it is just easier. Do the bottom of the pickguard anywhere the cavity is open underneath, do not worry about doing the whole pickguard. Also ensure the control and pickup cavity wrap comes up and over the screw holes so the screws have to pierce the shielding, it ensures optimum contact.

    If you need more help please feel free to PM me, I hate hum and try to remove it from every bass I can.
     

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