Humbucker issue/question

[Landon]

Hey all,

Thanks for checking in on my new thread. So my issue is that after replacing the humbuckers in 2 of my guitars I've picked up quite a bit of new noise. It's ground-ish sounding, but I'm skeptical of that because when I'm switched in to the middle position (of a 3 pos. switch) the noise is all but gone. When I single out one of the pickups (treble or rhythm position) the hum is very significant. My first questions is A) I replaced the stock humbuckers with PAF's (Duncan SH-55's in one guitar and Classic 57's in the other, all 2 conductor-style) so I was wondering if the lack of wax potting would add THAT much noise? And because of the lack of noise in the center position, do these pickups cancel noise when working together like some single coils will? If neither of those scenarios seem probable then I would love to hear any suggestions you may have. I've checked the grounding a few times, as well as added copper shielding, but it hasn't helped. I'm pretty close to just completely desoldering everything and starting over, but I wanted to get some input first. Any help will be very appreciated. Thanks in advance.

-Landon-

[big_teee]

I have a few questions.
Can you please tell what guitars you are referring to.
Was anything changed accept the pickups?
Is this with amp in clean mode, or under high gain conditions?
I would start real simple trying to isolate.
I would plug straight from guitar to amp no pedals, no high gain.
All the info you have, and pictures would help.
It sounds like it could be a grounding issue.
The middle posistion would have both humbuckers in parrallel.
Please share as much info as possible?
Later,
Terry

[lexluthier72]

A photo would help....as clear as possible, in focus. Sounds like something is not hooked up correctly. Humbuckers do not have the same action as single coils unless they are hooked up incorrectly. They should be fairly quiet all the time, in any position. Also, any thing else in the room that would provide 60 cycle hum?...(ie, flourescent lights, furnace, etc..) wax potting does not nessesarily take away hum, it will take away squeal/feedback. We need more info.
-E.

[Landon]

Hey Terry, thanks for the reply.

1) the first guitar is an Epi Dot, and the second is an Epi Black Beauty. (high-class guitars, I know, ha). In the Dot I put the duncan SH-55's. I did replace the pots in that guitar about three months prior, but I didn't have any issues between then and replacing the pickups. The Black Beauty got the 57's and I didn't change anything else on it.

2) The noise is present with the amp in every possible scenario, from clean and quiet to dirty as can be. I've definitely isolated the problem to the guitar by using different amps and bypassing all pedals/plugging directly to the amp. The two things that make me skeptical of it being a ground issue are A) the noise is NOT effected by touching any or all of the metal parts on the guitar, including pots, pickups, strings, tuners...etc. Obviously touching certain places on the pots introduces new noise, but it doesn't effect the old noise. And B) The noise IS effected by my relationship to an amp, i.e. the direction, distance and angle to the amp will lessen or increase the noise a bit. Because of that fact, I put copper shielding (grounded) in the cavities, but that really didn't seem to help at all.

I'm really pretty stumped. Any suggestion at all is a welcome one. I can try to take some pictures tomorrow...Thanks again.

[Landon]

Hey Lex,

Is there a particular issue that you know is a common mistake that would cause the humbucker to be hooked up incorrectly, making it act like a single coil? I may start there if you know of something...

And what, in particular, do you need to see a picture of? The pots or cavities or...???

Thanks for checking in.

[big_teee]

Hi Landon:
Well I would work on the les paul type first.
It's easier to work on.
If you want to prove the pickup and isolate things, here's some things you can try.
I've done this myself on some guitars.
To prove how quiet the pickup is the quietest would be to bypass the switch and wire one pickup to one pot.
so if you have the wire I would try wiring from the jack to the vol pot, to the pickup.
If that is quiet then connect the tone pot to the vol. pot.
If that is quiet then wire one pickup through the switch without the other pickup wired to the switch.
Keep putting it together until you get rid of or get the noise back.
I guess your wiring looks something like this but 2 wire?
Terry

[lexluthier72]

Landon...They should both be 2 wire type pickups, with a hot, and a braided shield, if I remember correctly, about the only thing you could have going on is poor solder joints, which usually cause the guitar to lose signal, it can also cause static, among other noise. Could be a loose wire...Could be part of the hot signal (ie, a pot leg) touching the side of the cavity and partially grounding...Hard to tell without seeing it. A photo of the cavities would be good.
-Erin
p.s.- If they are four conductor wire coming off the pickups, I would then assume that one coil of each pickup is shorted. (this can be caused by not taping up the end of the series link, and letting the wire just hang in the guitar)

[StarryNight]

just to add to the problem solving: when you tap on the screws and slugs of each bobbin with a screwdriver do you hear a pop sound from the amp?

[Landon]

So basically, I started the process of troubleshooting that Terry laid out, and the first thing I did was wire the bridge pickup directly to the output. I didn't even use the volume pot, just straight to the pickup and the noise was still there...Does that mean I have a bunch of defective pickups? But why is the noise gone when two of them are working together? I really don't get it.

[Landon]

Now I just did another little test. I took one of the pickups completely out of the guitar to test it. I wired it by itself to an output jack and plugged it in to an amp...same result, BUT when I press the pickup against a sheet of copper shielding tape the hum decreases quite a bit. It's not all the way gone, but it's attenuated significantly. Does that tell me that these are VERY sensitive to interference? Any thoughts out there?

[big_teee]

Now I just did another little test. I took one of the pickups completely out of the guitar to test it. I wired it by itself to an output jack and plugged it in to an amp...same result, BUT when I press the pickup against a sheet of copper shielding tape the hum decreases quite a bit. It's not all the way gone, but it's attenuated significantly. Does that tell me that these are VERY sensitive to interference? Any thoughts out there?

Just to prove a point you might try taping the whole pickup cable.
Leaving only the shield exposed enough to connect to the jack.
I prefer 4 wire insulated cable over the uninsulated.
I think the exposed shield may be picking up noise.
If the taping helped, You might get some heat shrink at radio shack that will fit over the shielded braid.
If they were mine I would desolder the nickel cover, change out the cable.
Pot the pickup with the cover off, retest it.
If all is well, put a little hot wax in the cover and solder it back on.
Please let us know how it turns out.
Good Luck,
Terry

[jason lollar]

sounds like your string ground is no longer connected

[lexluthier72]

any new news on this? On the note of copper shielding....yes your pickups may be sensitive to RF signals (60 cycle hum)....you can try shielding the actual pickup routes on the LP....on the epi dot....Id try shielding the bottom of the pickup and the braided lead off the pickup....try copper taping it and then some sort of shrink tubing....Be sure to look for things within the room that provide more RF interference....(ie, lights, improper grounded plugs on your amp, microwave ovens, etc) as those things will increase the noise ratio....let us know what you find.
-Erin
p.s.- Ive never had potting a pickup solve 60 cycle hum.

Edit: Jason....I think you are on the right track..... =)