First-timer diagnosing wiring issue

Gdecernay

TDPRI Member
Joined
Jul 2, 2020
Posts
57
Location
West Coast
Hi all,
I’m doing a rewire on a Korean Epiphone Sheraton II. It’s been neglected for a while, so finally switching out the pickups and wiring to make it more of a daily player. I’m running into some issues, and with this being my first time on a project like this, some of the troubleshooting tips online haven’t gotten me in the right direction. I’ll try to outline where I’m at as best I can.

Both pickups appear to be working. They’re older Phat Cats, and touching the hot tip of my multimeter to the inner wire and the ground to the braided sleeve shows readings of 8k ohms and 7.5k ohms. So, that is leading me to believe the pickups are working. I’m following a Sheraton II wiring chart (attached), which has the input also connected to the cap. The second lug is the output going to the switch.

I’m not getting any signal when the wiring is complete. Each pot is grounded in a horseshoe pattern (attached) and I’m running the ground from the switch to the wiring coming from the pickups, soldering them together and running the output to the Jack and the ground to the inner ring on the Jack. The ground from the bridge thimbles is grounded to the back of the neck tone pot.

When I measure the connection on the pot that is the input taking the pickup lead, I get the correct ohm reading. I get this reading on the wire to the cap too. However, at that point all signal stops. It looks like with the pots turned down I get the correct 0 reading showing it all going to ground, but when the pots are open, it looks like there is a short, as I get no numerical value at all.

So it looks like signal is getting out of the pickups, to the cap, and then just stopping or shorting out somehow.

Again, first time with a project like this, so happy to clarify anything that doesn’t make sense above. Any thoughts would be greatly appreciated!

Thanks!
 

Attachments

  • D924D6EB-9D7D-49FC-88E7-FC4AA6BA1E3F.jpeg
    D924D6EB-9D7D-49FC-88E7-FC4AA6BA1E3F.jpeg
    74.9 KB · Views: 21
  • 6F18F041-CFAA-4E61-9480-0CF54AAF409E.jpeg
    6F18F041-CFAA-4E61-9480-0CF54AAF409E.jpeg
    103.3 KB · Views: 21

Peegoo

Doctor of Teleocity
Joined
Oct 11, 2019
Posts
13,399
Location
Beast of Bourbon
Your signal is shorting to ground somewhere.

Working inside a hollowbody can make a person crazy. Do you have the entire circuit outside the guitar body? If so, snap a pic of it (several pics with close-ups will be hugely helpful) and post 'em here.

Even when we work from a layout or schematic, we sometimes goof up. And because we've looked at the wiring so many times, the mistake is right in front of us and we miss it.

When I have this problem, I get a 2nd pair of eyeballs on it to compare what I have with the drawing. Those eyeballs don't have to belong to anyone that knows anything about electronics...and they will usually see my goof-up.
 

Peegoo

Doctor of Teleocity
Joined
Oct 11, 2019
Posts
13,399
Location
Beast of Bourbon
And this is unrelated to your issue but considered standard practice: you want the hotter pickup (8K) in the bridge position and the weaker pickup (7.5K) in the neck position. This makes for more balanced output. But you probably already know that.
 

Gdecernay

TDPRI Member
Joined
Jul 2, 2020
Posts
57
Location
West Coast
Hi thanks for the replies! Yes on the outputs; was just showing that the pickups were working.

I think I got it figured out. I scrapped the wiring I’d been using according to the Sheraton diagram and went with one from Seymour Duncan on the Phat Cats specifically with a three-way switch. It was lot of smaller ground points than I had been using, but getting signal through the output now.

I might still have a grounding issue on the neck…
 

Gdecernay

TDPRI Member
Joined
Jul 2, 2020
Posts
57
Location
West Coast
Ok so still definitely a grounding issue. I’m getting signal out of the output into an amp. I think it may have to do with the ground to the thimble under the bridge, or at least that type of grounding. When I touch the metal switch to a string, I get normal output without any ground noise. With nothing touching the string, I get the ground noise.
 

Peegoo

Doctor of Teleocity
Joined
Oct 11, 2019
Posts
13,399
Location
Beast of Bourbon
Ok so still definitely a grounding issue. I’m getting signal out of the output into an amp. I think it may have to do with the ground to the thimble under the bridge, or at least that type of grounding. When I touch the metal switch to a string, I get normal output without any ground noise. With nothing touching the string, I get the ground noise.

That means everything is working and your string ground is connected. The reason for grounding the strings is to use the capacitance of the human body (your fingers on the strings) to serve as a noise filter. The strings act like an antenna and they will add noise to the signal.
 

Gdecernay

TDPRI Member
Joined
Jul 2, 2020
Posts
57
Location
West Coast
Right, that makes sense. I think I’m still confused as to why touching the metal switch tip to the string eliminates all buzz and normal output. My hands will act the same way as the metal tip when everything is reinstalled and I’m touching the strings?
 

Gdecernay

TDPRI Member
Joined
Jul 2, 2020
Posts
57
Location
West Coast
Thanks again for the tips! Now that it looks like everything is actually connected properly, I’m going to redo the wiring. The troubleshooting left the pots and soldering joints looking pretty junky. I’ll post some pics of the redo for some clearer shots if trouble persists.
 

Gdecernay

TDPRI Member
Joined
Jul 2, 2020
Posts
57
Location
West Coast
Hi all, thanks again for the replies. Been working on this from scratch according to the diagram from SD for Phat Cats. I’m convinced the grounding issue stems from the multiple points on the bridge tone pot. I’m getting signal from the neck, but the bridge is shorting everything out. I’ve attached the diagram I’m working from and pics of things on my end. Forgive the soldering massacres. The troubleshooting has left things less than clean. 514B8BA3-4081-486B-9CEE-D31E0A4E42B6.jpeg
 

Attachments

  • 993C5874-A1A3-47AB-8C60-0BAAD0ADACEF.jpeg
    993C5874-A1A3-47AB-8C60-0BAAD0ADACEF.jpeg
    158.6 KB · Views: 13
  • D553F6C0-A168-4FF6-89F8-5393922322E7.jpeg
    D553F6C0-A168-4FF6-89F8-5393922322E7.jpeg
    159.6 KB · Views: 15
  • DAA8DC91-F0C9-4368-B987-998EE8DF983D.jpeg
    DAA8DC91-F0C9-4368-B987-998EE8DF983D.jpeg
    199.1 KB · Views: 16
  • 220CEBB9-F657-42F0-AC50-4AC4542C5D5F.jpeg
    220CEBB9-F657-42F0-AC50-4AC4542C5D5F.jpeg
    158.6 KB · Views: 12
  • FB632D96-AA90-4938-A781-A6BC44F522D7.jpeg
    FB632D96-AA90-4938-A781-A6BC44F522D7.jpeg
    109.5 KB · Views: 14

nathan5782

Tele-Meister
Joined
Jan 31, 2020
Posts
455
Age
45
Location
Sacramento, California
It looks like some of the braided wiring might be touching the pot lug, you can trim that part back a little and the other picture looks like the end of a wire might be touching both lugs but maybe it's just the angle from the picture.

Sheraton_pots2.jpeg


Sheraton_pots1.jpeg
 
  • Like
Reactions: SbS

schmee

Telefied
Silver Supporter
Joined
Jun 2, 2003
Posts
20,694
Location
northwest
Some wiring schemes ground the switch case. But quite often, these issues are the metal braided pickup wire used. I keep the braid away from pots and switches as best as possible. Often I solder both braids together and run a single small covered wire to the ground collection point.
 

Gdecernay

TDPRI Member
Joined
Jul 2, 2020
Posts
57
Location
West Coast
I think I understand what you’re saying. Are you saying that you don’t solder the braid to the back of the pot and that you solder the two braided leads together? And is there a best practice on a good ground collection point? The Seymour Duncan diagram looks like it uses the bridge tone for that, but other diagrams show other options. Does the type of pickups used play a role in the ground collection point?
 

Gdecernay

TDPRI Member
Joined
Jul 2, 2020
Posts
57
Location
West Coast
Got it working! Followed the SD diagram to the letter. Also used a smaller soldering tip. I think part of the problem was that the Epiphone uses the small pots. Not a lot of real estate to make connections and keep them separate and clean. Also opted for this way of grounding the pickup lead. Firgured since the braid was ground, just make a little nib to connect and keep it away from the lugs. image.jpg
 




Top