Duotone Custom Wiring assistance requested

[DavidE]

I tried to find diagnose the hum issue with my duotone custom today. No luck after probing everything. But one of the two ground wires from the EMG preamp board came undone, or was not connected, while I was working on the guitar. If I touch this ground wire, the hum problem disappears. But touching the wire anywhere in the guitar does not get rid of the hum.

Anyway, does anyone have a wiring diagram or a photo of the duotone wiring guts? OR, if you can tell me where the top ground wire (2 away from the green wire) goes, I'd appreciate it.

As for the ground issue, here's what I found:

The humbuckers were changed to a PRS McCarty neck and a DiMarzio DP155 in the bridge. While it's not the focus of my issue, the pickups sound fine alone, but when both are on it sounds a bit thin, like perhaps they're wired out of phase. Anyone know whether these pickups are wired the opposite of each other?

Anyway, onto the issue. There is quite a bit of hum coming from the under saddle piezo pickup whether using the stereo out or the piezo only out. I can make the hum stop by touching one of the pickup covers. Since the saddle isn't metal, touching the strings doesn't stop the hum.

I've opened it up, tried to figure out if there's someplace I could run a ground wire that would take care of the issue, but I could not figure out a way to cure the issue.

I also found that then I put the three way switch (for humbuckers/piezo/both in the humbucker only setting, there was no hum unless I touched the metal part of the switch. Could this all be caused if the Dimarzio is wired differently from the PRS pickup?

[DavidE]

I received wiring diagrams from Kim Keller for the DuoTone Custom dated 5/2002 and 5/2007, but neither shows the ground wires coming from the preamp board.

Is anyone willing to take a look inside theirs and tell me if they have two black ground wires coming off their preamp board?

Thanks

[sonic1974]

I received wiring diagrams from Kim Keller for the DuoTone Custom dated 5/2002 and 5/2007, but neither shows the ground wires coming from the preamp board.

Is anyone willing to take a look inside theirs and tell me if they have two black ground wires coming off their preamp board?

Thanks

Is the Duotone Custom wiring different from the 3 holer versions? I have a three holer, I could check it out when I get home from work.

[DavidE]

Is the Duotone Custom wiring different from the 3 holer versions? I have a three holer, I could check it out when I get home from work.

Yeah, it's different. I have 3 two holers but they don't have a stereo jack etc...

Nobody else is willing to open up their guitar and let me know where the one wire goes? It doesn't show up on the wiring diagrams from Kim Keller.

Thanks.

[veatch]

Here's a couple of pics from a 3-holer:

Let me know if you need another shot.

[DavidE]

Thanks. It's amazing how much cleaner the control cavity is in a three holer! Much less wirig. I spent about an hour and a half on it tonight (maybe a little more) and I finally discovered that little hole in the side by the battery compartment that a ground wire must have gone to at some point and that some moron must have removed. It must be attached to one of the string through grommets on the back, but with the wire gone on mine, I'm not sure how to hook up a new wire. I figure that's got to be it.

I started by desoldering the magnetic pickups to get them out of the circuit and made sure they weren't part of the problem. Of course as I poked and prodded trying to figure things out, a couple of the wires came loose so I had to redo those.

But ultimately, there must be a way to run a new ground wire through that hole in the side but I can't figure out where it goes and what it attaches to. I try putting a solid copper wire in there and couldn't get it to work. Argh. I'm guessing that I need to remove the grommet for at least the high string on the back of the guitar, but not sure how you do that or even if it can be done.

Very frustrating, but I feel I'm closer.

[tomteriffic]

Dave, sorry I missed this until now. I checked my preamp board and there's only a red power wire coming from the battery and a single fat black one with two conductors coming off of there. One conductor goes to the back of the piezo volume pot, the other to an outside lug of that pot. I also checked behind the battery and there is, in fact, a green (therefore ground) wire running into that tiny hole. If this were an Artist, I'd be guessing that it would be going to the bridge as a string ground. As it is, I don't know.

There's so much stuff going on in there, Id make sure that there aren't any loose ends, etc., that are fine when the cavity is cracked open, but that press together or, say, touch the back of a pot when you screw the cover back on.

Dang, I hope I didn't get my hum back when I did that just now.

[DavidE]

Dave, sorry I missed this until now. I checked my preamp board and there's only a red power wire coming from the battery and a single fat black one with two conductors coming off of there. One conductor goes to the back of the piezo volume pot, the other to an outside lug of that pot. I also checked behind the battery and there is, in fact, a green (therefore ground) wire running into that tiny hole. If this were an Artist, I'd be guessing that it would be going to the bridge as a string ground. As it is, I don't know.

There's so much stuff going on in there, Id make sure that there aren't any loose ends, etc., that are fine when the cavity is cracked open, but that press together or, say, touch the back of a pot when you screw the cover back on.

Dang, I hope I didn't get my hum back when I did that just now.

Thanks Tom, you're a peach. I wonder why there are so many incarnations of the electronics???

Anyway, I'm sure it's that green wire going into the side that's the issue. I need to figure out how to replace that.....

[tomteriffic]

Just a suggestion: Try using a jumper wire from wherever that ground wire connects inside the cavity to various likely spots for the other end to go (string ferrule?), and see if the hum goes away. At least you'll have a clue as to where to look for the other end of the tunnel.

[kriszguitar]

The strings are grounded by a drain wire that goes through all six grommet holes on the back. You can use a guitar string or a solid hook up wire to do this if it has been removed.

Kris

[DavidE]

The strings are grounded by a drain wire that goes through all six grommet holes on the back. You can use a guitar string or a solid hook up wire to do this if it has been removed.

Kris

Kim Keller talked about "major surgery" to replace that wire. Not sure how to remove the grommets or can I just run a really long solid wire into the hole?

[anotherfreak]

Hey,

I don't have a custom, but Maybe if you posted a pic of yours, something might jump out that one of us could spot.

just tryin' to help

[Jackass]

The two black wires off of the EMG Preamp are grounds. The acoustic pot doesn't look grounded. Bend green ground wire over and solder to the side of the small pot. That wire that goes through all the grommets isn't a big deal. Rule of thumb. If it takes more than 5-10 minutes to isolate a wiring problem, just replace everything.

Bm

Did they really fucking kill off Brian Griffin? Fuck.

[kanegon]

The ground wire from the preamp board to the piezo-acoustic pot is actually the shielding for the wire to the pot, you should be able to trace it back to the board. Looks like the red wire from the preamp goes to the pot and the clear wire to the piezo, both shielded and grounded to the board. Don't see any other ground wires.

OOPS, mine is a 3 hole, didn't realize the Customs had a single stereo jack. Could you post those Kim Keller diagrams?

[marcnorth]

It's a 25K

[Studio Custom]

Get rid of the stereo jack, make the piezo one jack and the magnetics another.