Help grounding issue

Discussion in 'Epiphone SG' started by Lunacy the Faded, Sep 18, 2018.

  1. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    My 1990 Epiphone SG has weird wiring I don't know why theres a buzz sound from it on high gain

    Unless I touch the jack, humbucker height screws or the three way switch...

    It then has almost no hum/signal buzz touching one of those and touching any of the three with the strings makes for no buzz at all

    Other SGs I touch the strings and it's totally buzz free..
     
    Last edited: Sep 19, 2018
  2. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
  3. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    My other SGs don't have wiring like this, the capacitors go across the pots on my Gibson's and there is no buzz sound on the same high gain channel when I touch the strings
     
  4. cerebral gasket

    cerebral gasket Well-Known Member

    Joined:
    Jan 13, 2017
    Messages:
    1,686
    Likes Received:
    1,855
    The tone pot for the bridge pickup appears to have a short between the middle and outer lug where the cap is connected. Looks like either a solder bridge or the lead from the cap is bridging the two lugs together. Maybe bend the leads of that cap over to the other side of the pot so that it is not crossing over the center lug.

    If touching the strings has no effect, then make certain the ground wire from the bridge is properly connected by checking continuity between the bridge and one of the pot casings. Make certain everything is properly grounded at the pups, pots, switch, output jack, bridge.

    I bought a used 2003 SG Special Faded a while back, gutted the entire cavity and replaced everything inside it to tidy things up a bit.

    [​IMG]


    The PCI Bus hydroplaned while trying to cross the solder bridge.
     
    Last edited: Sep 18, 2018
  5. Six Stringed Demon

    Six Stringed Demon Active Member

    Joined:
    Aug 25, 2018
    Messages:
    114
    Likes Received:
    110
    Location:
    Valley of the Sun
    Holy crap @cerebral gasket thats one of the cleanest cavities I’ve ever seen! I’m tempted to redo my robot to be on your level then get a clear (rather than smoked) cover for it!
     
  6. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92

    Yeah I see that will move the bridge tone cap to hang off the other side thank you

    So the black wire going into the hole of the body must be wired to my bridge but it might not be making contact?

    I'll see after moving that cap if the issue persists

    I really need to do a full rewire on my 2002 it's much messier than your before pic of the 2003... :facepalm:
     
    Last edited: Sep 20, 2018
    cerebral gasket likes this.
  7. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    @cerebral gasket would you happen to have any info on the bridge ground wiring process, and should I use a thicker guage wire like the gibson SG?
     
  8. donepearce

    donepearce Well-Known Member

    Joined:
    Dec 12, 2012
    Messages:
    3,306
    Likes Received:
    2,830
    Location:
    London, helping a friend design a knitting machine
    This is a very common problem that guitar manufacturers should have dealt with long ago. The hum is coming from your body. That is why it disappears when you ground yourself to a pickup. You need to shield the control cavity with copper foil, and particularly the back cover plate which is the part closest to you. Ground the foil to a pot body once you have installed it. You don't need to be anal about covering every square inch - a reasonable covering will do the job.
     
    Lunacy the Faded likes this.
  9. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    I think I fixed it!!

    Yes that cap was close I stood it upright then I looked at my toggle switch under the tape was okay but I made some more adjustments but the real issue was the ground wires' solder not sticking on the three way switch, I got it globbed up and hot then pulled it in and it's got full contact now

    Really good info here now though.. thanks a bunch ESG!
     
    Last edited: Sep 20, 2018
    cerebral gasket likes this.
  10. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    :h5:
     
  11. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    After actual comparison it was still not grounded properly so I put a little shield on a suspected ground short at the switch
     

    Attached Files:

    Last edited: Sep 20, 2018
  12. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    Nope, maybe it's that short red wire I used to reach the ground signals to the switch..

    Before I replace that I used my dremel to scuff the back of the tab and primed it with solder
     
    Last edited: Sep 20, 2018
  13. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    Trying a new wire to bring those grounds to the switch
     
    Last edited: Sep 20, 2018
  14. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    Well everything's in check and it seems to be the bridge is not grounded so now I'm scratching my head
     
  15. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    When I first got the SG this was overhanging and I cut it flush ... is that the black bridge ground?
    Screenshot_20180919-141609.png
    (That's the pickguard side tailpiece post)

    I don't know if I need to pull this out to correct the issue because I just soldered what's left of that wire to the post hole and it didn't fix the issue with the ground buzzing sound in my signal..

    Only thing to quiet it is touching the jack, toggle switch, pointers or the humbucker height screws
     
    Last edited: Sep 20, 2018
  16. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
  17. donepearce

    donepearce Well-Known Member

    Joined:
    Dec 12, 2012
    Messages:
    3,306
    Likes Received:
    2,830
    Location:
    London, helping a friend design a knitting machine
    That shouldn't have been left hanging out! It's the end of the wire that grounds the strings via the stop bar. It goes into the control cavity and the other end gets soldered to a pot body.
     
    Lunacy the Faded likes this.
  18. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    I think that it's connected to the pot body but what if it's not connected to the stop bar anymore?

    I soldered the little squished ends that were left to it but it didn't fix it...
     

    Attached Files:

  19. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    Okay so I tried this to strengthen the ground circuit..

    Ran another white copper wire from the jacks ground connection to the back of the neck tone pot which has that black ground wire to the stopbar/bridge/strings
     
    Last edited: Sep 20, 2018
  20. Lunacy the Faded

    Lunacy the Faded Active Member

    Joined:
    May 25, 2018
    Messages:
    148
    Likes Received:
    92
    Everything stays put with the cover on like this

    All the switch connections are stronger and cleaner

    Still buzzes when I hold the strings unlike other SGs

    20180919_154551.jpg
     
    Last edited: Sep 20, 2018

Share This Page


Recommended Links: PAF Pickups, Luthier Forum