Norlin era groundwire (TP bushing to pots)?

[1981 LPC]

My LP Custom has developed a buzzing sound that only goes away when I touch the jack plate. I think it's a grounding issue. Checking continuity with a multimeter, there is no continuity between: strings / bridge / tailpiece <> jack plate / switch / pickups / pots

In a related post in the Luthier section members pointed out to check the wire that should connect the TP bushing to the pots (photo). But... my Custom doesn't have that wire. Or that hole...

Is this a Norlin era thing?

 

[dubster82]

Yeah, you should have your pots attached to a metal plate then an "ashtray" sort of lid over it enclosing them. That was their method of shielding they went with.

 

[mudface]

My LP Custom has developed a buzzing sound that only goes away when I touch the jack plate. I think it's a grounding issue. Checking continuity with a multimeter, there is no continuity between: strings / bridge / tailpiece <> jack plate / switch / pickups / pots

In a related post in the Luthier section members pointed out to check the wire that should connect the TP bushing to the pots (photo). But... my Custom doesn't have that wire. Or that hole...

Is this a Norlin era thing?

View attachment 668392

Yup,... once the can ('75 - '82) was in use they dropped the ground wire from the TP post anchor. Though you could always pull the threaded TP post anchor and drill a small hole to the cavity and install your own ground wire. I haven't done it with mine as mine seem fine without it, but it's an easy job for a qualified luthier or you could look up a DIY vid.

 

[geezbill]

do yourself a favor and pull the lower tailpiece stud and drill a hole to the control cavity, run a ground wire to it. Been down this road .

 

[Juan Tumani]

Agree with all above.

I'll say though that instead of pulling the bushing for the stop tail, pull the bushing for the bridge even though it's a farther distance to have to drill.

The reason for this suggestion is that the stop tail bushings can be incredibly tight which sometimes makes them very hard to get out. On the flip side they need to be very tight so they don't pull out and if it doesn't go back in super tight you may have issues with it moving later on.

The bushing for the bridge is typically easy to remove and there is very little force put on that bushing by comparison. If you don't want to drill a long distance straight into the control cavity, you can just drill a short hole into the bridge pickup cavity and run a slightly longer grounding lead alongside the pickup lead.

 

[1981 LPC]

Thanks everyone. It was supposed to have been installed over 20 years ago, when the original pots crapped out and the tech mentioned it didn't have one.

 

[gball]

Agree with all above.

I'll say though that instead of pulling the bushing for the stop tail, pull the bushing for the bridge even though it's a farther distance to have to drill.

The reason for this suggestion is that the stop tail bushings can be incredibly tight which sometimes makes them very hard to get out. On the flip side they need to be very tight so they don't pull out and if it doesn't go back in super tight you may have issues with it moving later on.

The bushing for the bridge is typically easy to remove and there is very little force put on that bushing by comparison. If you don't want to drill a long distance straight into the control cavity, you can just drill a short hole into the bridge pickup cavity and run a slightly longer grounding lead alongside the pickup lead.

This is how I did it. The pots in my '79 finally gave it up a few months ago, and when I rewired it it had hum even though I used the original faraday shields, so I ran the ground wire from the treble side bridge stud into the bridge pickup cavity just as you mention. It was an easy fix and the guitar is dead-quiet again.

 

[HardCore Troubadour]

I bought a 76 Custom once with a red ground wire running from the bridge-post to the vol pot across the top.

I removed it and the guitar lost all of it’s tone and it could never be recovered and I had to sell it.

True story and there’s a thread here with pics somewhere.

 

[dubster82]

It's odd you say its just developed a problem if you haven't changed anything. Has anything changed?

I kinda feel if you run a ground wire, you may have the same buzzing that will actually stop when you touch the strings instead of the jack plate.

If you want to check, wrap a wire tightly round the tailpiece, then run that round into your control cavity. That means you get to check your theory without drilling holes or removing hardware.

 

[1981 LPC]

It's odd you say its just developed a problem if you haven't changed anything. Has anything changed?

I kinda feel if you run a ground wire, you may have the same buzzing that will actually stop when you touch the strings instead of the jack plate.

If you want to check, wrap a wire tightly round the tailpiece, then run that round into your control cavity. That means you get to check your theory without drilling holes or removing hardware.

I noticed it recently when I bought a modelling amp (Mustang GTX50). Never had problem with a Marshall solid state amp and a Fender Blues Junior valve amp.

 

[1981 LPC]

There, I fixed it! Pulled out the bridge bushing (treble side), drilled a hole to the bridge pickup cavity and installed a ground wire.

I MacGuyvered this together. Worked fine.

 

[dubster82]

I noticed it recently when I bought a modelling amp (Mustang GTX50). Never had problem with a Marshall solid state amp and a Fender Blues Junior valve amp.

Don't you think it could be the amp then?

I'll also say, I had a weird buzzing, had no idea what it was. Changed cable, guitar to one with active pickups, amp, nothing cured it. Turned out it was living room dimmer switch, switched the lights off, all quiet.

 

[dubster82]

There, I fixed it! Pulled out the bridge bushing (treble side), drilled a hole to the bridge pickup cavity and installed a ground wire.

I MacGuyvered this together. Worked fine.

I don't get what you've done here. The wire is just supposed to be sandwiched between the bushing and the wood inside the hole

 

[1981 LPC]

Don't you think it could be the amp then?

I'll also say, I had a weird buzzing, had no idea what it was. Changed cable, guitar to one with active pickups, amp, nothing cured it. Turned out it was living room dimmer switch, switched the lights off, all quiet.

Well I returned another digital modeling amp before I got this one, having the same problem and thinking it was the amp.

 

[1981 LPC]

I don't get what you've done here. The wire is just supposed to be sandwiched between the bushing and the wood inside the hole

Yeah, that's what I did. But I had to first pull out the Faber iNsert that replaced the Nashville bushing. It rather sturdy compared to the Nashville bushing.

 

[mudface]

There, I fixed it! Pulled out the bridge bushing (treble side), drilled a hole to the bridge pickup cavity and installed a ground wire.

I MacGuyvered this together. Worked fine.

Excellent work,... now you got extra tonez