Problems with switch-wiring (?) - both pickups are on in all positions

Norba

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Hello everyone,

I've been an occasional reader here but I only decided to register now because I have a problem that I couldn't find a solution for.
I've bought a guitar on eBay (it's a Gibson SG Special, but we can pretend it's a Les Paul because wiring wise they are almost the same :p) that had it's pickups changed to Burstbucker Pro's but the nut was chipped. I tidied it up, changed the nut - for the first time ever -, set the string height and all sorts of things but now that I finally could play it I noticed that both pickups are engaged in every switch positions. What is more weird is that both tone knobs are on as well.
So I messed around and this is what's going on in each positions:

Neck: both pickups are on, both tone knobs are on, only neck volume is on
Middle: everything is on as intended
Bridge: both pickups are on, both tone knobs are on, only bridge volume is on

It seems like both tone knobs act like 5-5, so if I want full tone I have to set both of them on 10, if I want 1 I have to set both of them to 1. For 5 I guess I only have to set only one of them to 1.
Checked wiring diagrams online and the wires themselves, apart from one loose grounding wire for the neck pickup - which I soldered back - I saw no real problems. Although the capacitors connected to the bottom lug of the volume pots which I changed back(?) to the middle lug.

One other weird thing is when a string touches the pickup it shorts out everything, no sound at all. I tested on other guitar, besides the loud noise prodced by this contact the other strings should be fine and heard.

If you have ideas, suggestions, questions please don't hold back. I actually kind of enjoy doing this, a little project fixing a nice guitar. :)
IMG_20200814_081611.jpgIMG_20200814_081622.jpgIMG_20200814_081627.jpg

The loose yellow wire was attached to both volume pots to ground, I changed that connection to the braided wire according to wiring diagrams - I had no better idea what could cause the problem at this point.

Thanks.

Norbi
 

ARandall

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Your braids are ground, and they seem to be close to the switch leaves. The braid should be insulated where it enters the cavity, ending close to the vol pot where it cannot touch any connections save the pot back it is soldered to.

You will need also to doublecheck the switch connections. You need to know how the switch makes the elcectrical connection from the switch volume pot middle lugs (the source of the pickup signal from each, and how the switch works to (de)select the undesired pickup signal. You will then see the switch 'leaf' (and connecting wire) that goes to the output jack.....there is one leaf for each pickup, and these tend to be squeezed together so 1 wire is used for the output signal.

Also there is the large chassis ground of the switch in this location. That obviously cannot touch any of the signal connections at all.
 

Norba

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I don't see the pickup wires touching anything except each other but thanks for pointing that out, I should put some insulating tape on that one.
I tried to make new photos. The yellow wire on the neck side goes nowhere - it was soldered to the neck vol pot but I detached it. The yellow wire on the bridge side is soldered to the braided wire's metal shielding which is soldered to every pot and ends in the output jack. The hot wire of this starts at the bottom (from this angle) of the switch with the 2 metal sheets that are pushed together.
The switch mechanically seems to be fine, when I switch it up or down the metal sheets move and they get separated. Since the volume knobs are engaged according to the switch position it indicates to me it's fine. But somewhere some connection is messed up that I can't see.
If there was a site to design guitar circuits I'd make a drawing.
IMG_20200814_103728.jpgIMG_20200814_103956.jpgIMG_20200814_104023.jpgIMG_20200814_104029.jpg
 

ARandall

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The yellow wire on the neck side goes nowhere - it was soldered to the neck vol pot but I detached it.
The yellow wire is switch chassis ground. That goes to the back of the pot.


The other connections on the back of the pots could do with being reflowed.....if not removed, the solder sucked up and completely re-done.
In fact the pickup install is very poorly done, for many reasons:
Firstly - the green wires have been burnt by the iron in multiple spots.
Secondly - The joints on both pot backs are poor (as mentioned)
Thirdly - it looks like they connections are backwards......the black cloth covers the inner hot wire (now connected to the back of the pot) which should be soldered to the pot lug. The braid (or in this case the green wire) is ground for the pickup covers and baseplate. It is attached to the pot back usually - not the hot wire/pot lug
You should move (or remove) the bridge and neck white coverings so you can see just what is attached to what.
This would explain the string hitting the pickup casing and no sound.

A the moment unless there is something else obvious, it will be a case of signal tracing......a multimeter set to say 20k ohms and see where you are getting contact (0 ohm reading)
I fear though that a lot of the wiring in the signal path might have to be either re-done, or at least touched up. Its not the best job in there.
 

Norba

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Thanks, I will reattach the yellow wires then as they were before. I just saw in some wiring diagrams that this part of the switch should be connected to the outside of the braided wire to ground it, that's why I made this change.
By the way, I found it odd that the braided wire that goes from the switch to the output jack was not connected to the neck volume pot to ground it so I did that.

I believe this guitar has been through a lot of abuse and whacky work from the previous owner(s) so I'll try to make it work like it should be. I will detach the pickup wires and check if it was switched around.
By the way, after you mentioned that I searched for Burstbucker pro wirings and it seems like it might be a 4 wire pickup and if that is the case the green is not even the hot but the one used for coil splitting.
To be honest when I plugged the guitar in it sound Tele-ish and hummy, so I might just have an SG wired in a coil tapping way maybe... :D

I hope if I was able to fix it I wouldn't be so disappointed with the real sound after.

I will do some work on it next week probably, I will update this thread if there's anything new.
Thank you for the suggestions.
 

AlanBiker

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If it were mine I would take out all the wiring and redo from scratch with new caps.

Gibson_SG_wiring_diagram.jpg

Les Paul wiring.png


Alan
Gibson_SG_wiring_diagram.jpg
Gibson_SG_wiring_diagram.jpg
Les Paul wiring.png
 

AlanBiker

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Sorry for the double images - don't know what happened there!

Alan
 

Norba

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Sorry for the double images - don't know what happened there!

Alan
Hi,

Thanks for the tip. I've actually done one for my Vintage V100 Les Paul copy. Bought some Japanese pots - metrics, so they fit in the pot holes -, some orange drop caps and wires. I went for the 50's wiring. I actually enjoyed doing that.
Since the SG has Gibson components I didn't want to change the whole thing - or start from scratch. The factory wiring was fine, only the pickup wires were messed up by some previous owner.
 

Norba

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Hello everyone,

Yesterday I managed to fix it thanks to the tips I got. What I found surprised me but considering the state of the guitar I shouldn't have been surprised that much. :D
So this is what I found after I removed the neck and bridge shrink tube from the wires of the pickups.
IMG_20200822_131354.jpgIMG_20200822_131406.jpgIMG_20200822_131411.jpg

The ground was wired as hot and the hot was ground - as you suspected.
I changed to the correct way and now it sounds like an SG should. Who knows how long it has been since this guitar sounded properly.
To be honest for a little bit I hesitated if I should repair it. It sounded kind of Telecaster-ish - or at least single coil-ish. And since I don't have a Tele, for a moment I thought leaving it as it is but I'm glad I repaired it in the end. Now that it's done it was a fun little project. :)

Sorry, I'm not going to post a photo of the finished wiring because it's messy. I'm not really good at soldering and the tip accidentally melted some wire isolation here and there but it works. :fingersx:
 

Cjsinla

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Glad you figured it out. I was gonna tell you that the green is not the hot. Those pickups were set up for PCB. I would’ve cut the end off and wired it old school, Braid soldered to the back of the pot and center wire to the lug on the pot. Is that what you ended up doing?
 

Norba

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Glad you figured it out. I was gonna tell you that the green is not the hot. Those pickups were set up for PCB. I would’ve cut the end off and wired it old school, Braid soldered to the back of the pot and center wire to the lug on the pot. Is that what you ended up doing?
I was going for that "old school" method that you mention. I've gotta admit, I was a little too enthusiastic to do that because after I removed the green wires I realized that the wire of the neck pickup is not long enough - since I cut off a little bit with the old solder.
So I had to reattach the green wire to the braid to ground it and add a little wire to the hot one to reach the lug. But it works. :)
 


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