LP Replaced Pickup issues

[M3mPh1z]

Hi Guys

 

I am having an issue with my Gibson LP (1981 Deluxe)

 

The previous owner replaced the bridge pickup with a dimarzio super distortion, the problem is when I have that pickup selected, I get very bad buzz from the guitar.

 

It seems to be a grounding problem but I am no electrician and have very basic understanding of electrical faults.

 

I have notice if I touch any of the metal contacts on the guitar (other pickup, toggle switch, jack port) [Not the bridge or strings] the noise goes away

 

 

Also if I have only the neck pickup selected there is no noise.

 

Any one have an idea as to how I can get rid of this noise?

 

Thanks

[badbluesplayer]

It might have something to do with how the pickup wiring was hooked up. Can you take a pic of the wiring inside the control cavity cover on the back? Then maybe somebody can tell what's wrong.

[nikininja]

Cold solder joint maybe?

 

Have a look at the back of that pickups volume pot. Check the colour of the solder. You need those solder joints to be shiny and clean. A dull, grey or powdered look to the solder joints signifies solder that hasn't cooled properly and may have hairline fractures in the join. This can cause momentary shorts to the circuit or impaired signal passage. Which can manifest as the symptoms you describe.

 

Also look at where the braided ground wire is soldered to the back of the pot. Check if the solder looks to have been applied in lumps. One lump on top of the other. To reach the top of the braided wire. That can have problems where the two joining bits of solder have cooled at different intervals.

[M3mPh1z]

I believe this is the correct pot?

 

 

wiring does look a little dodgy

[nikininja]

The center of the ground wires solder joint looks a little matte. Like it was added on top of the existing solder.

 

Just run a hot soldering iron over it to melt all the solder together. So it all cools at the same speed. Or alternatively get the old solder off the pot and re-wire it. That's one possible culprit out the way. For a couple of minutes work.

 

Though re-reading your initial post it could be a pot problem. Do you have any spares knocking about? The good news is that the problem is definitely on the bridge pickup. So you can narrow it down to that side of the circuit. I wouldn't suspect the switch. When they go bad it usually manifests on both sides of the switch on a guitar thirty years old.

 

Also there is no ground bus wiring from pot to pot. E.g

 

 

Is that negated by the metal plate that the pots are mounted onto? (Sorry not experienced enough with Gibson to know).

[Bender 4 Life]

you're sure both halves of the bridge p'up are working?

i've seen cases where the bridge p'up was wired to only function as a single coil.....and being a "Super Distortion"....it would likely buzz like a f'ing beehive if that's the case.

[badbluesplayer]

Different pickup brands have different wiring color schemes. If it was me, I would figure out whether the pickup wires are going to the right places before trying to resolder anything. I could help you figure out whether the wires were hooked up to the right places if you took a pic of the wiring from that pickup. Preferably a pic of the whole control cavity. I'm wondering if the guy hooked them up to the right contacts.

[kaicho8888]

It appears the bridge has the hot and ground reversed...similar to when you touch the hot lead of the cable that's plug in the amp. As BadBlues mentioned check the manufacturer's wiring colors.

[Angellus]

 

 

Also there is no ground bus wiring from pot to pot. E.g

 

 

Is that negated by the metal plate that the pots are mounted onto? (Sorry not experienced enough with Gibson to know).

 

yes the metal plate is the common ground on these les pauls

[MattUK]

The fundamental problem I see there is that the braid screening of the pickup cable is not soldered to the earth. It looks like the internal wires are connected but the screening is not!

[Angellus]

The fundamental problem I see there is that the braid screening of the pickup cable is not soldered to the earth. It looks like the internal wires are connected but the screening is not!

 

oh no its that guy again.

 

as a Brit I would like to totally apologise for this guy

 

the braided wire is a historic design still used by Gibson (even though they did vary during some years) and perhaps some other guitar manufacturers. Yes it is used to earth the pickup.

 

However.....aftermarket (unless traditional gibson is what your looking for) pickups and all modern designs are shielded with foil lined plastic coat. the earth unbraided wire(s) are then twisted together and soldered to the back of the pot. Sometimes it is its own plastic coated wire the same as the live wire.

 

So in this case the green wire could very well be the earth from the pickup. Difficult to tell without inspecting the guitar personally ESPECIALLY if the previous owner worked on the wiring himself.