Help grounding issue

[Lunacy the Faded]

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..

 

[Lunacy the Faded]

 

[Lunacy the Faded]

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

 

[cerebral gasket]

View attachment 32926

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.

The PCI Bus hydroplaned while trying to cross the solder bridge.

 

[Six Stringed Demon]

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!

 

[Lunacy the Faded]

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.

The PCI Bus hydroplaned while trying to cross the solder bridge.

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...

 

[Lunacy the Faded]

@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?

 

[donepearce]

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]

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!

 

[Lunacy the Faded]

If touching the strings has no effect, then make certain the ground wire

Make certain everything is properly grounded at the pups, pots, Switch, output jack, bridge.

 

[Lunacy the Faded]

After actual comparison it was still not grounded properly so I put a little shield on a suspected ground short at the switch

 

[Lunacy the Faded]

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

 

[Lunacy the Faded]

Trying a new wire to bring those grounds to the switch

 

[Lunacy the Faded]

Well everything's in check and it seems to be the bridge is not grounded so now I'm scratching my head

 

[Lunacy the Faded]

When I first got the SG this was overhanging and I cut it flush ... is that the black bridge ground?

(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

 

[Lunacy the Faded]

Getting cleaner..

20180919_144953

• Lunacy the Faded
• Sep 19, 2018

 

[donepearce]

View attachment 32936

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]

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.

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...

 

[Lunacy the Faded]

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

 

[Lunacy the Faded]

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