1978 Les Paul Custom pickup swap, and 50's style re-wire

[Greg_L]

So...I was gonna wait till I was done and just do the thread all at once, but I'll get this started and post as I go along.

The backstory...

I have this 78 Les Paul Custom. Original pots, pickups, switches, etc. Cool guitar, heavy as fuck, and it plays great. But, it buzzes a bit.

The legend of quirky 70s Gibsons is alive and well in this guitar. After much research and exploratory investigation, I know why it hums and buzzes - a grounding problem and a shielding problem. So, I'm gonna fix it. This aint no case queen. I play this bitch. The quirky part is this era of Gibsons has no bridge/tailpiece ground wire! WTF! Every guitar in the world has that ground system, except for 70s Gibsons. In their infinite wisdom, they achieved grounding and shielding through a system of metal cases and boxes surrounding all the internal electronics, and shielded wire. And here's where it's important to me - the pickup covers are part of the ground/shield circuit. My guitar has the original pickups, but the covers have been removed at some point in it's almost 40 yr history. This breaks the "faraday cage" and let's the unwanted noise in. I installed a simple jumper wire from the bridge to the internal grounding and the guitar got quieter, so I know what to do. I need to drill a hole from the tailpiece bushing hole into the control cavity - like every guitar in the world already has...except for 70s Gibsons. Am I happy about drilling a hole into a vintage guitar? No, not really, but it's mine and I wanna play it. It will be invisible and just like guitars are supposed to be. With that ground wire, and my new uncovered pickups, this makes the rest of the metal box shielding all up inside the guitar moot, so it will all be removed and re-wired like a normal Les Paul. Hopefully I will have a silent guitar up until I bang a chord.

The pickup swap part is unnecessary for this repair. All it needs is that ground wire. I just wanted new pickups. It's all a simple process, but I'm going full monty on this thing. So here's where we start....

The subject



The "ash tray" surrounding the pots



Ash tray removed, exposing pots/control cavity. Note the large metal plate that everything is mounted to instead of just being mounted to wood. This is ground zero, pun intended. Everything grounds here. I might keep this plate as it's convenient, but I'm worried it might create a ground loop with standard wiring. I'll probably remove it since I want to wire the guitar "regular".



The selector switch cavity. Note how this entire cavity is actually a metal can pressed into the wood. The shield braid of the wire grounds on the can itself. The other end grounds at the plate. I'll probably keep all of this as-is. I'm gonna look for 4-conductor shielded wire tomorrow, but if I can't find it locally, it will definitely stay as-is.



This little can with the wire coming out of it's butthole hides the input jack. It's in there. More shielding. I like this. It will stay.



And this is the north wall of the control cavity. This is the neck vol/tone control side. See that little sticker? In that general area there should be a hole with a wire coming though it. That's where the new hole will be drilled. About an inch behind that wall is the tailpiece stud.



So that's where I'm at. Just exploring and planning. Actually, I've been exploring and planning, but just haven't done anything yet. I'm going to record some "before" clips before I tear it apart. We'll A/B the before and afters when it's all done.

I guess the next update will be teardown and drilling that damn hole.

[Bubba]

Excellent, Greg- I'll follow this with interest seeing as I'll be wiring mine up in the near future. I'm using the coil split on the bridge, too.

Have you made any attempts to pull the bridge stud yet? IMO, that's the trickiest bit if you don't want to damage the finish. The way I've managed it in the past is to replace the bridge post with a tailpiece post to give you better purchase when pulling. I wrapped masking tape around it, too. I used a pair of pincers to grab the post and pulled, rocking the whole thing gently until I got it out. I must stress that this worked for me, but I didn't actually care whether the finish stayed intact on the donor guitar when I pulled it out, although no damage was done. Worst case scenario is that the bushing is mega tight in the hole. Someone like Muttley would know better what to do in that situation.

Regarding drilling the hole, you could go direct to the wiring cavity once you get the bush out, which is about a 30mm distance. That's a bit long for a standard thin drill bit, such as a 1.5mm, but you gould go to the bridge pickup rout instead and ground to the pickup wire if it has braided shielding,which is about half that distance, or take the grounding wire back to the wiring cavity via the existing channel.

Good luck with it.

Edit: just noticed you're going from the tailpiece. That's fine, then. My controls are further forward, meaning the volume pot on mine is equidistant between the bridge and tailpiece studs.

[Greg_L]

Thanks Bubba. I've pulled tailpiece studs before, and the way I do it is to use the screw and busing against itself. Remove the tailpiece screw, drop something down the hole, like a small bolt or a dowel, and put the screw back in. As you re-tighten the screw it pushes against the small bolt you dropped down the hole. Since there's nowhere for anything to go, the screwing action pulls the bushing up. The bushing will walk up the tailpiece screw. This usually works on the cheaper, younger guitars I've done it to. On something this well made and old, that bushing may be real tight. I don't know. We shall see.

As for drilling the hole, I have some very long drill bits. It shouldn't be a problem going from the tailpiece hole to the control cavity. That is how the vast majority of Les Pauls are grounded throughout history...except for the 70s. Lol. It's only like maybe 3/4 inch from the tailpiece to the cavity...or as you said roughly 20-30 mm for your part of the world. The length of the bit makes going in at an angle no big deal.

I'll be going through like this....


Hopefully my drilling hand is steadier than my MSPaint hand.

It's been literally freezing in Houston, and it's an NFL playoff weekend, so naturally I've done nothing at all so far but sit around in sweatpants and watch football. I did make this handy but mostly unnecessary template though. I'll connect everything I can to this rig and then just drop it all in.

[Bubba]

the way I do it is to use the screw and busing against itself. Remove the tailpiece screw, drop something down the hole, like a small bolt or a dowel, and put the screw back in. As you re-tighten the screw it pushes against the small bolt you dropped down the hole. Since there's nowhere for anything to go, the screwing action pulls the bushing up. The bushing will walk up the tailpiece screw. This usually works on the cheaper, younger guitars I've done it to. On something this well made and old, that bushing may be real tight. I don't know. We shall see.

Actually, that's a fucking great idea. I will be doing that myself, from now on!

I like your component mounting board, too - very good if one is a bit fumble-fingered and prone to burning oneself with the soldering iron!

[JD01]

Good luck, Greg. I would be so nervous drilling holes into anything I care about!

[Greg_L]

Actually, that's a fucking great idea. I will be doing that myself, from now on!

I think it's good because it A) pulls the bushing straight up and out. No rocking or wiggling required, which could damage/elongate the hole. And B) There are no pliers or other finish-damaging tools in use. You just turn a screw and the bushing comes out.

I like your component mounting board, too - very good if one is a bit fumble-fingered and prone to burning oneself with the soldering iron!

If I didn't have the coil split pots, I'd just do it in the guitar. Les Pauls are easy. But I need to run one tiny ground wire from each push/pull pot that would be pretty difficult to do inside the guitar, so template method it shall be. And...I'm only so-so at soldering.

[Greg_L]

Good luck, Greg. I would be so nervous drilling holes into anything I care about!

Ha, it's really not a big deal. The way I see it, the worst thing that can happen is I could nick the finish on a part of the guitar that's completely hidden by the tailpiece anyway. It doesn't have to be a very precise surgically accurate hole. Any hole drilled through the tailpiece stud bore will land inside the gigantic control cavity. It's like drilling through the side of a bathtub hoping to poke through into the bathtub. You can't miss.

[ido1957]

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[Bubba]

If I didn't have the coil split pots, I'd just do it in the guitar. Les Pauls are easy. But I need to run one tiny ground wire from each push/pull pot

Ah, you're using push/pull pots? I understand they're what Gibson use for their coil split, but I much prefer push/push pots myself. One little tap either on or off and you're back to playing - it's so quick you can do it between strums, whereas with push/pulls it's easy to fumble if you fail to grip the knob firmly. So to speak.

[Greg_L]

Ah, you're using push/pull pots? I understand they're what Gibson use for their coil split, but I much prefer push/push pots myself. One little tap either on or off and you're back to playing - it's so quick you can do it between strums, whereas with push/pulls it's easy to fumble if you fail to grip the knob firmly. So to speak.

I'm not a fan of push/push. They are more user friendly for sure but they're flimsier and more prone to fuckups IMO. Either way, I'll probably very rarely actually use the split function. Especially not mid song. I just don't play that way. I'll roll the vol, but not actually split the pickups. I'm only doing it because I can. That's also why the splits will be via the tone pots. I hardly ever mess with the tone controls, and I hardly ever wanna split a pickup, so the tone pot is perfect for that feature.

All of these pots are CTS 500k audio taper, so the quality should be good. I've measured them and they're very accurate.

[Bubba]

I'm not a fan of push/push. They are more user friendly for sure but they're flimsier and more prone to fuckups IMO. Either way, I'll probably very rarely actually use the split function. Especially not mid song. I just don't play that way. I'll roll the vol, but not actually split the pickups. I'm only doing it because I can. That's also why the splits will be via the tone pots. I hardly ever mess with the tone controls, and I hardly ever wanna split a pickup, so the tone pot is perfect for that feature.

All of these pots are CTS 500k audio taper, so the quality should be good. I've measured them and they're very accurate.

Yeah, my split is going on the tone pot. It's out of harm's way there, but still easily accessible. I use the coil split quite often mid-song. For instance, on English Civil War I like to start the rhythm playing with the single coil sound - it just sounds great and authentic with the sound thinned out and scratchy, then when the lead breaks come I can switch in the full 'bucker at the same time as stomping on the channel change. There are a few songs like that.

[Greg_L]

Yeah, my split is going on the tone pot. It's out of harm's way there, but still easily accessible. I use the coil split quite often mid-song. For instance, on English Civil War I like to start the rhythm playing with the single coil sound - it just sounds great and authentic with the sound thinned out and scratchy, then when the lead breaks come I can switch in the full 'bucker at the same time as stomping on the channel change. There are a few songs like that.

Yup, that's good use of a split.

Part of the reason I'm such a stickler for good pickup/amp interaction is that I'd rather just roll off the vol a bit to clean up. My Goldtop Traditonal has coil splits, and I literally never use them. Never. The split is just too much. It gets too thin and bright. When I split it I have to roll the tone off too, and that's two operations I don't want to do. That guitar's pickups and pots are so perfect in HB mode that just a little roll back on the vol is all I need. It cleans up and I don't lose any treble. That's what I want from the Custom.

[Greg_L]

Well fuck, my medium power soldering iron took a shit. Won't get hot. My only other iron is super mega high power and way too much for the more delicate work, so I guess I'll be buying a new soldering iron tomorrow.

[Bubba]

Well fuck, my medium power soldering iron took a shit. Won't get hot. My only other iron is super mega high power and way too much for the more delicate work, so I guess I'll be buying a new soldering iron tomorrow.

What do you call medium power and super mega high power?

Best solution - get a temperature-controlled iron.

My iron is a 40W variable - I think that'll be enough for the big joints, such as grounding the pot casings. What do you think?

[JD01]

My coil splits sound pretty good, but they're not as good as the real thing... Which is probably why I enjoy playing single coil guitars so much.

When I record it's almost always with humbuckers, when I'm just sitting in the house messing about I often play with split coils. It's probably just more dynamic and not as compressed so is just more interesting when you're messing about.

My soldering iron was the cheapest beginner kit from Maplin. It was good enough for rewiring my wah wah, so will probably be ok for most guitar related problems.

[Greg_L]

What do you call medium power and super mega high power?

Best solution - get a temperature-controlled iron.

My iron is a 40W variable - I think that'll be enough for the big joints, such as grounding the pot casings. What do you think?

40w will probably be enough to solder to the backs of pots. I think 40-60w is ideal for that job. But I'm no pro solderer or anything.

My "medium power" iron is 30w. I've used it for guitar wiring, pickups, amp mods, car wiring, everything. It struggles with large quick heat tasks like sticking blobs of solder onto the backs of pots though.

My super mega high power iron is like 80w, and it's heavy duty. It will melt through damn near anything. It's got a large tip. It will easily solder to the back of pots, but it's a bit heavy handed for finer stuff. I used to use it for wiring up RVs and Winnebagos. Lol. They have miles of heavy gauge wire running through them so you need a powerful iron to get all that done.


I took my iron apart just now and cleaned it up and tightened everything. It's working again, so yay!

[Bubba]

I took my iron apart just now and cleaned it up and tightened everything. It's working again, so yay!

Excellent - I hate retiring decent gear.

[Greg_L]

Excellent - I hate retiring decent gear.

Ha yeah, well it's far from decent gear. I was halfway excited to go buy a nice new iron, but hey, it still works so it'll be put to use.

[Greg_L]

Ok, I just recorded by "before" clips, so it's officially time to dig in!

Hopefully that will not be the last time this guitar made sound lol.

[Greg_L]

A little progress. The pot template board is wired up. Not the nicest looking solder blobs, but the fucker is stuck together and all the connections are solid and the ground circuit has perfect continuity.



I left the vol pot side cap lugs open because the pickup selector wires also go to those lugs. I'll solder them all together in the guitar.