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Hum issue with 2010 Les Paul Traditional Pro

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by emdub123, May 20, 2011.

  1. emdub123

    emdub123 Supporting Member

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    Hi, long time lurker, first time poster here.

    I live about 100 miles from the nearest guitar tech, so I need to try and fix my geetar myself and I'm hoping someone here can help.

    Here's the problem: The guitar makes lots of noise (sounds about like 60 cycle hum, but it's getting louder), which is virtually eliminated when touching the metal ring surrounding the pickup selector. My suspicion is that this means a loose wire/bad solder in the selector, is this correct or are there other more likely culprits? I have a soldering iron and have swapped pickups before, so I've got a basic skill but don't know how to deal with this.

    Any ideas?

    Thanks!
     
  2. Dana Olsen

    Dana Olsen Gold Supporting Member

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    More info please. Is the hum present on BOTH pickups, or just one, and which one? Does it hum on all positions of the p/u selector switch?

    Any change when turning a vol or tone knob when it's humming? If so, which knobs cause a change?

    Obviously you've lost a ground somewhere, ya just gotta figure out where, right? You choices are the pickup leads where they're soldered to the pots, the pots, the switch, or the ground wire that grounds the bridge.

    Hope this starts some help, Dana O.
     
  3. Mark Kane

    Mark Kane Silver Supporting Member

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    So, the only place you can touch the guitar and make it stop is the switch ring?
     
  4. emdub123

    emdub123 Supporting Member

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    Hi guys thanks for jumping in!

    Dana: Yes the hum is present on both pickups equally, as well as the middle position. I think you're right regarding a grounding issue, so if it stops when I touch the metal ring surrounding the pickup selector, would it be safe to assume that this is the source of the grounding issue? I can't make the hum stop by touching the pickups or the volume/tone knobs.

    Mark: Yes, that's correct. I can only make it stop by touching the switch ring. Touching the pickups doesn't eliminate the noise.

    So, assuming it's a bad ground in the pickup selector switch, what do I do? On a les paul, how do you deal with a bad ground on the pickup selector?

    thx!
     
  5. Dana Olsen

    Dana Olsen Gold Supporting Member

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    Hi Emdub - It's not necessarily the switch itself. What the evidence shows is that the ground is not present on either pickup, and that means that somewhere you lost a ground that affects the grounding of both pickups (like the bridge ground wire).

    Does the hum also stop if you touch the bridge?

    Thanks, Dana O.
     
  6. Trebor Renkluaf

    Trebor Renkluaf I was hit by a parked car, what's your excuse? Silver Supporting Member

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    Does the hum stop when you touch the strings? If so, it works like 99% of the electric guitars manufactured. Look at the wiring diagrams for a typical Gibson style electric.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Notice they ALL have a "ground to bridge" or "ground to tail piece".

    What touches the bridge and tail piece? The strings. What touches the strings? Your hands? What does this mean? You are ground.
     
  7. doveman

    doveman Member

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    The reason there is a ground wire to the bridge is not to connect the circuit to the player. You are not the ground. This is sort of an interesting take on it ... but I think more correct.

    http://www.guitarnuts.com/technical/noisebucket.php
     
  8. doveman

    doveman Member

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    I ran across this link that I posted a while back while on the LP forum. I thought about a couple of ground/noise threads here recently. I think it does a great job talking about not only proper grounding but also how noise is related to proper grounding. Clears up some unintended misinformation here in this thread I think ... worth listening to.

    http://www.taylorguitars.com/see-hear/Video.aspx?file=AudioGrounding_High.wmx

    I had a Gibson LP Traditional that still had noise that I could only get rid of by doing propoer shielding in the guitar. I had already checked the ground ... I had a proper ground already. So even a humbucker guitar was picking up noise. After shielding it was quiet ... much better.
     
    Last edited: Jun 12, 2011
  9. emdub123

    emdub123 Supporting Member

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    Sorry for the late follow-up everyone, but for the benefit of folks who dig this thread out of the archives, the problem was that the ground to the bridge was disconnected somehow. Prior to this discovery, I had de-soldered and re-soldered every connection between the pickups and pots and it didn't help. I eventually took it in to a tech who discovered the disconnected ground wire.

    Thanks for the assistance, everyone.
     
  10. Crowbar

    Crowbar Member

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    Poking around with this issue myself. If the ground to bridge wire is busted, how to reconnect it? The wire just goes into a little hole in the body. I just stuffed it back in there and checked that continuity is there but it dosn't feel like a good fix. I guess I gotta pull a tailpeice stud, shove the wire in from the control cavity then screw the stud back on top of it.
     
  11. Jef Bardsley

    Jef Bardsley Member

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    Yep. With a search you can find instructions for pulling the TP studs.
     
  12. walterw

    walterw Gold Supporting Member

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    if you don't wanna risk the finish like that, here's a "cheat";

    get a long, skinny brass screw, maybe 1". (brass is important here). screw it into the hole the groundwire came out of, all the way down until it hits the bushing and is tightly against it.

    solder your groundwire to the head of the screw (that's why you need brass, so the solder will stick.)

    (edit) it occurs to me that the hole for that wire might actually run under the bushing, in which case a screw would miss it entirely. you would then need to drill a hole a little above the original so that the screw actually lands on the metal tailpiece bushing.

    when i run into '80s les pauls, where gibson had the idea that they could just shield everything under metal cans and covers and skip the groundwire, my usual fix is to drill the new path and use a screw rather than pull the bushing out.
     
    Last edited: Nov 14, 2011
  13. Trobbins3

    Trobbins3 Silver Supporting Member

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    I'm experiencing this issue with my new LP Traditional. The issue is much better when my hand is in contact with the strings or bridge, but it is very noticeable when not.

    May have to have the grounding and shielding improved on the guitar.

    Any input would be appreciated.
     
  14. walterw

    walterw Gold Supporting Member

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    if touching the strings makes the noise go away, then the grounding is fine.

    you can reduce the noise with thorough shielding, but that's more of a mod than a repair.
     

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