#1
I have a pretty loud hum from my guitar, when I open the control cavity and touch ground there is no change in the noise. I bought this guitar used so I have no idea how well the upgraded pickups were installed, the solder joints looked fine though. How can I figure out what is causing the noise without straight up desoldering everything and redoing it?

electronics are a 5way switch, volume, and tone knob. If I turn the tone knob all the way off the noise goes nearly entirely away.
Last edited by ninjab at Nov 20, 2009,
#2
Theres your answer, check the ground and solder joints to on the Tone pot.


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#3
I don't think it is a grounding issue, because if I touch the casing on the tone pot(grounding it) it is still just as loud.
#4
If you touch your strings, does the noise/hum go away?
next time, please take this to the ultimate wiring thread.
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#5
there is usually a grounding that goes to the bridge or a part on the trem of a guitar. check that.
#6
sorry didn't notice there was a thread for wiring issues

Hum does not go away when I touch the strings, and yes the ground that goes to the strings/bridge is soldered to ground inside the control cavity.
#7
Quote by ninjab
I don't think it is a grounding issue, because if I touch the casing on the tone pot(grounding it) it is still just as loud.



I think it is a ground issue because of what you just said. a guitar is normally wired so that when you touch your bridge, which has a wire grounding it to another ground wire, most of the unwanted noise goes to ground through you. but since when you touch anything that's supposed to be ground it doesn't make any difference than I would assume that there's a problem, but as far as your tone knob having something to do with it idk. I know that the extra noise gets quieter on my bullet as well, and it's wired properly, so it may have nothing to do with your problem.
Last edited by The4thHorsemen at Nov 20, 2009,
#8
^right I think the tone knob may be irrelevant

If it was a grounding issue though, I would think if I touched the volume control casing (ground) the noise would be reduced, right? -it doesn't change touching any ground plane.
#9
Quote by ninjab
^right I think the tone knob may be irrelevant

If it was a grounding issue though, I would think if I touched the volume control casing (ground) the noise would be reduced, right? -it doesn't change touching any ground plane.


it's supposed to reduce the noise when you touch ground, yours doesn't, therefore I think there is a grounding problem
#10
Quote by The4thHorsemen
it's supposed to reduce the noise when you touch ground, yours doesn't, therefore I think there is a grounding problem


ok, I see what you are saying. Any way to tell what part of the circuit is not grounding right?
#11
um, well I'd just look to see if the ground wires are all finding a path to ground and if I didn't see anything I'd try resoldering anything that didn't look to great. but I don't really know. if you can't figure it out post some pics and maybe someone will see something.
#12
Due to all the ground loops in a guitar, you're best off to just resolder all the ground wires. TBH, i'd also remove the ground loops because they pick up more noise.

If the pots and switch are connected through the foil on the pickguard, then leave the pup and jack grounds where they are and just get rid of those short wires between the pot casings.

just fyi, the tone pot cuts noise because noise is mostly high frequencies. tone controls shunt high freqs to ground and out of the signal.
#13
Quote by Invader Jim
Due to all the ground loops in a guitar, you're best off to just resolder all the ground wires. TBH, i'd also remove the ground loops because they pick up more noise.

If the pots and switch are connected through the foil on the pickguard, then leave the pup and jack grounds where they are and just get rid of those short wires between the pot casings.

just fyi, the tone pot cuts noise because noise is mostly high frequencies. tone controls shunt high freqs to ground and out of the signal.


thanks for the clarification on the tone pot, I was thinking its effect was something like that.

--I thought I might have a probably with the 5-way switch, took it apart and cleaned with alcohol, didn't help any.

I guess when I have a free afternoon I will need to just rewire the whole thing, might as well put better pots and shielding in while I'm at it.
Last edited by ninjab at Nov 20, 2009,
#15
Quote by Invader Jim

If the pots and switch are connected through the foil on the pickguard, then leave the pup and jack grounds where they are and just get rid of those short wires between the pot casings.


No pickguard on it, and everything going to ground goes to the volume knob casing, actually looks like it is wired correctly, I don't see any obvious ground loops.
#16
Check the wiring, I had similar problem with my NEW Epiphone, and it turn out to be a wiring mistake, some china guy wired the bridge humbucker wrong: ground wirer was wired as signal wire and signal wire was wired as ground, so I switch them and the noise was gone
post some good picture of the controls, maybe someone will find a mistake there
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#17
ok I'm trying to figure out the wiring for this
I have a 5way switch made by schaller with a liner arrangement. It has terminals numbered 1-7 and an extra terminal not connected to the switch simply attached through the screw holding the PCB board to the switch (I will call this x)
Attachments as follows:
x: grounded to Volume pot, connected to 5
1: Neck (white and red wires)
2: Volume pot
3: Bridge (white+ red wires)
4: Bridge (green wire)
5: Grounded to volume pot through x
6: Neck (black wire)
7: Bridge (black wire)

According to seymour duncan's wiring diagram http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=2hb_1vol_1tone_5way the green wires from both pickups should be grounded (The neck green wire is grounded to the vol pot). So I don't know why bridge green is connected to 4. I have no idea how this switch translates to the conventions listed on sd diagram so I can't figure out what else is wrong.

Thanks for any help
Additional info:
Shields (bare wire) are both grounded to vol pot
Last edited by ninjab at Nov 24, 2009,
#18

Seymour Duncan wiring codes (not 100% sure these are right):
HUMBUCKER WIRING COLOR CODES:
Most Seymour Duncan humbuckers with four-
conductor wires use the following color code:
Green = beginning of adjustable coil (South)
Red = finish of adjustable coil
Black = beginning of stud coil (North)
White = finish of stud coil

After finding this schematic and converting the colors according to SD's nomenclature, I've confirmed that my wiring matches the wiring in this picture. So there shouldn't be any problems with the switch wiring.

What type of wiring is this megaswitch schematic? Split, out of phase, parallel, etc?
Last edited by ninjab at Nov 24, 2009,
#19
reheating the ground solder joints did not help either.

Is it possible that this is just the background noise of my SH4/SH2 pups? I figured the noise was an issue since it is considerable louder than my junk stock schecter pups, but are these SD pups known to be noisy?