LP Standard Bridge Post Ground Issue

[Timmsie95]

Alright, so ever since I got my Gibson Les Paul Standard, back in 2009, I've noticed the pickups aren't all that quiet. Now that I know a bit more about electronics, I pulled 'er out and checked it out.
So I checked the continuity between the switch and pickups and all that.

Bridge pickup and switch are grounded

Neck pickup is grounded

Wait a minute...

So the bridge isn't grounded correctly. great, but why?
There's a wire coming from the bridge post to the control cavity...
(by the way, I hate this solderless system...)

Then I noticed something...

So, my thinking, is that the wire going into the bridge post hole, is most likely along the bottom of the cavity, but since for some reason the post isn't threaded all the way in, it isn't making contact with the bridge post.
Why the hell are the posts not in al the way? I don't know... This guitar has multiple little things that make me think I should have gotten it at B stock prices, but didn't. For instance, There are a few areas with red felt tip pen marks, like around the pickguard mounting hole, and on some binding on the neck. One of the tuners was installed slightly cockeyed, which you don't notice at first, but when you see it, it's there forever. one of the volume knobs as cracked right down the middle from day one, the control avity cover was way too tight of a fit, and I had to sand it back about a half mil to get it to fit right... and there are a few inconsistencies in the goldtop paint. Not to mention how thin the clear coat was applied, and it will chip if you hit it with a towel...

ANYWAYS
So if I'm correct, tightening down those bridge posts should get rid of my hum issues, right?
One day I'm going to remove the solderless system and have it properly wired with vintage shielded cable, and take the locking neutrick jack off and put a normal one in.
For my most expensive guitar, it has the most issues!

 

[Timmsie95]

So I tested my theory, and screwed down the bridge posts, but the hum is still there. it goes away when i touch the switch or pickups, but not when I touch the bridge... This doesn't really make sense to me and I don't know what to do next... the tailpiece looks better now, though  :laughing7:

 

[mayfly]

I'm guessing that the studs are not grounded.  I'm afraid that the only way forward here is to pull them and attach the wire properly.

 

[Timmsie95]

I had a feeling...
Dammit.
There is no fun way to do this...

 

[Verne Bunsen]

Before conducting surgery, I'd use your meter to test continuity between the ground wire and the tailpiece bushing. If you have continuity there but not to ground then the problem is in the control cavity. That string ground is just a wire stuffed in the bushing hole with the bushing pressed in on top of it, not a whole lot to go wrong on that end unless the wire is physically broken. Does it pull out of the hole or is it solid?

 

[Ace Flibble]

These problems are not rare and they're almost always solved at the control PCB.

The studs, and the ground wire directly beneath them, should be fine. Gibson don't muck about with the ground wire to the stopbar, because they spray the clear coat over the bushings; they know they can't simply pull them up and reposition the ground wire if they get it wrong the first time. A few years ago they started soldering the wire to the bushing, in fact, though I don't remember if that had started by 2009.

In the very rare instances that you do need to pull the stopbar's bushings, prepare to crack the clear coat. You can minimise damage by running a good scalpel around the perimeter of the bushing a few times, then use a soldering iron to very, very lightly heat the paint which is directly on top of the bushing. That should cut the bushing and the clear coat on top of it free from the rest of the paint, so it can be lifted out without chipping the surrounding finish.

However, I've only heard of the ground wire not making proper contact with the stopbar once, and never encountered such an issue myself. On the other hand, problems with the PCB board and grounding are something I've had to fix more times in the last year alone than I can keep count of. So, chances are the problem is not underneath the bushing.

Because Gibson run that ground wire before they've sprayed the clear, the length of wire coming into the control cavity also gets coated with clear. They're meant to scrape this off before inserting it into its grounding station, but sometimes they just don't take enough off, or they forget entirely. I've also encountered guitars where they simply haven't shoved the ground wire far enough in to the socket.

So, first task is to lift the ground wire out of the PCB, give it a good rub down with some medium grit sandpaper, and shove it back in. Make sure you get it in all the way and fasten it down firmly. Then test again. Nine times out of ten, that will sort it out.

If that fails, my instinct is a fault with the PCB. Gibson's PCB set ups are typically really well made—as long as you don't want to mod the guitar, of course—but, just like with any control pots or switches, every now and then you're going to get a piece with a manufacturing defect. The 2008-2011 boards aren't used anymore and you can't get a replacement other than as part of repairs carried out by Gibson under warranty. So, if you can't swing a warranty repair, you're basically left with taking the PCB out and replacing it with regular control pots. If you like the taper and feel of the existing pots, Gibson's 300k and 500k pots are a perfect match. Obviously you can switch to CTS, Bourns, or other imperial-measurement pots, as you wish. (Gibson's pots are in fact made by CTS, but with a different taper than CTS' own pots.)


I have only ever pulled the bushings out of a Gibson after I've thoroughly tested the PCB and then, where necessary,  replaced the PCB with regular controls. Given the risk to the guitar's finish, it's not worth pulling the bushings until you've exhausted the possibilities within the control cavity.

 

[Timmsie95]

okay. well, i didnt know the wire would be coated with clear, so i tested it from two points in the middle, and got nothing. that would explain it... ill go back and try to sand off some of that clear now...

 

[Timmsie95]

THANK YOU

I sanded off some of the clear on the end of the ground wire, and i now have continuity!
I still get slight hum, especially through overdrive, but i've never had a guitar that doesn't.

 

[bagman67]

And here is why I love this board.  Smart folks who share their considerable experience.  Nice work, Ace, and good for you, Timmsie, for not being afraid to suss it out on your own.


Tough break about the miscellaneous low-grade defects on your axe.  At least you're developing solid qualifications to repair 'em!

 

[Timmsie95]

And here is why I love this board.  Smart folks who share their considerable experience.  Nice work, Ace, and good for you, Timmsie, for not being afraid to suss it out on your own.


Tough break about the miscellaneous low-grade defects on your axe.  At least you're developing solid qualifications to repair 'em!

Yeah, everyone on here is so helpful! Every issue I've had, or questions, someone is able to help me out.

I've learned that when you have this many guitars, it's well worth it to learn everything you can about them, and do your own repairs if necessary. saves money, and you gain useful knowledge.

As annoying as some of the defects are, I enjoy it when i set it up well, and it still plays great. Plus, you can only see the defects if you're looking for them!

 

[Ace Flibble]

Good to hear you got it sorted. I'm not surprised that you still get a little hum, as I think the 2009 Standards have BurstBuckers, yes? BurstBuckers have fairly mismatched coils, which helps open up the tone but means they're less efficient at cancelling 50/60-cycle hum. Same as the Seymour Duncan Seth Lover and the EMG 58.

As annoying as it is when an expensive guitar like a Gibson or American Fender has problems, I've always felt they're worth sticking with 'cause they always end up playing and sounding so good.

 

[Timmsie95]

Good to hear you got it sorted. I'm not surprised that you still get a little hum, as I think the 2009 Standards have BurstBuckers, yes? BurstBuckers have fairly mismatched coils, which helps open up the tone but means they're less efficient at cancelling 50/60-cycle hum. Same as the Seymour Duncan Seth Lover and the EMG 58.

As annoying as it is when an expensive guitar like a Gibson or American Fender has problems, I've always felt they're worth sticking with 'cause they always end up playing and sounding so good.

Yeah, they're Burstbucker Pro's.
I've been thinking about getting different pickups for it, but I'd either have to get gibson pickups with the quick connects, or gut the entire thing, which i'm not opposed to doing. I love the look of a nice clean cavity with cloth covered wire and good quality pots!

 

[Ace Flibble]

You can attach the quick connect plugs to other pickups. The plugs are a standard Molex connector—the exact type has varied a lot over the last few years, but can be identified with clear pictures—and you can either attach them to the pickup yourself (cheap but very fiddly), or there's a chap on eBay who sells connector sets with colour-coded wires for various brands' pickups.

 

[Timmsie95]

I've seen those. I also thought about using the ones on my burstbuckers, and essentially doing what I would do if I had those connectors from ebay, and I'd be left with two normal burstbuckers.

 

[Timmsie95]

Since I naturally like doing things myself, I found the correct molex connectors and pins at Digikey.
Connector part number: 0436450200
Pin part number: 0430300009
Those are both the manufacturer part numbers.
So I'm just going ot order some of these, and some wire and heat shrink tubing, and away we go!