Stumped with HUM

SloMoTX

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I am having a problem installing new Tonerider Birmingham pickups - hum. It is not the pickups. I disconnected the PUs totally!
Just have the orange drop caps connected to the pots along with the grounding wire to all four pots. The output jack and grounding to the bridge is also soldered to the pots.

It has a hum with just this wiring. Very noticeable volume. Could I have overheated a pot and the hum is the result?

See the attached diagram.
1614725226652.png
 

Gibson Lover

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Have you tried a different guitar? If that’s not it sometimes grounding or lack of and is the wire to the bridge connected?
 

sonar1

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Ground loop.
Too many path to ground.
Cavity shielded? Then you don’t need ground wires too.
 

ErictheRed

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Ground loop is the most likely culprit, there's a reason that everything is usually grounded to one pot.
 

ARandall

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Cavity shielded? Then you don’t need ground wires too.
The ground completes the A/C circuit. Without the pickup wires that contact the pots having a sleeve jack connection there is no sound.

Doublecheck that the pot back and the bridge actually still have electrical connection. The horseshoe ground pattern is quite fine for guitars.
 

LP1865

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I gotta ask, does the hum stop if you place your hand on the bridge or the strings?
 

jonesy

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Humm and or buzz is always an indication of a partial short between hot and ground.

Find the short and you will get rid of the buzz.
 

LP1865

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Humm and or buzz is always an indication of a partial short between hot and ground.

Find the short and you will get rid of the buzz.
cant hum also be caused by a bad pot
 

SloMoTX

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Ground loop.
Too many path to ground.
Cavity shielded? Then you don’t need ground wires too.
Cavity is shielded. On Vol. pots - 4 grounds on each.
Shielding is with shield paint I think. It is black interior. Epiphone LP,
 

SloMoTX

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Ground loop is the most likely culprit, there's a reason that everything is usually grounded to one pot.
On all my guitars, there are more than 1 pot with the grounds. 1 ground wire to all 4 pots, 3 way switch to ground- pot, each PU has a ground to Vol, Tone pot has ground from a lug on each pot.
 

SloMoTX

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I will replace the 2 Vol pots. I figured how to use a single wire soldered onto the Vol pot back, then connect any other ground needed to that 1 wire. I will still have the one "U" shape ground wire to the 4 pots.
This will prevent overheating the pot (s). The one wire acts like a terminal block.

Thanks for the info. Time to get to work. ER- retirement!
 

ErictheRed

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On all my guitars, there are more than 1 pot with the grounds. 1 ground wire to all 4 pots, 3 way switch to ground- pot, each PU has a ground to Vol, Tone pot has ground from a lug on each pot.
Well, each pot needs to be grounded as well, but it's best to use the minimum number of wire loops (zero ideally). If you traced out the wiring, you might see that most components are grounded to one pot, and then from there a few "tendrils" go off to bring the ground to the other pots and the output jack. However, there shouldn't be multiple pathways from each of those farther away components to come back to the main ground.

Google "star ground" scheme or system. Here's one link with possibly more info than you need: http://www.geofex.com/article_folders/stargnd/stargnd.htm
 

LP1865

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I have the same problem honestly.
I think it's a bad pot. My neck volume doesn't go all the way to zero. Check your pots. I'm just to lazy to change mine and I keep using a noise gate instead.
BTW I'm also using tonerider and their coil split wiring diagram
 

geddy

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Is there any change if you set the volume to zero?
 

SloMoTX

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Well, each pot needs to be grounded as well, but it's best to use the minimum number of wire loops (zero ideally). If you traced out the wiring, you might see that most components are grounded to one pot, and then from there a few "tendrils" go off to bring the ground to the other pots and the output jack. However, there shouldn't be multiple pathways from each of those farther away components to come back to the main ground.

Google "star ground" scheme or system. Here's one link with possibly more info than you need: http://www.geofex.com/article_folders/stargnd/stargnd.htm
I think I finally understand grounding to one pot. Thanks.
 


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