Grounding Pickups...?

Gear
1

When I first got my Schecter, it had the problem where there was an electronic buzz that went away when I touched the strings, bridge, tuners, or pots. So, I shielded it using conductive paint and made sure the shielding was grounded via this process:

  1. I scored the back of the pick guard and painted it.
  2. I painted the entire electronics cavity.
  3. I painted the body above the lip of the electronics cavity, where the pick guard would cover, to allow for a connection between the paint in the electronics cavity and the paint on the back of the pick guard.

The existing ground on one of the pots was good, and after the paint dried and the bass was put back together, it was whisper quiet. Great success.

Yesterday, I installed my Seymour Duncan SPB-1 pickups in it. I first tried to ensure the pickups were grounded by following some advice I saw on a website: I wrapped the foam spacers in conductive tape and installed them under the pickups:

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Theoretically, as I understand it, this grounds the pickups via the shielding’s connection to ground. However, once the pick guard was installed and the connection completed, the bass made no sound. If I loosened the pick guard and broke the connection, the bass made sound. It was as if the output from the pickups was being shunted to ground.

I went through everything with a fine-tooth comb looking for some short in the wiring that was making contact when the pick guard was tightened down, but I could not find one.

So, I removed the foam spacers wrapped in conductive tape, and installed plain foam spacers. This fixed the problem; when the pick guard was tightened down and the connection established between its shielding paint and the shielding paint in the electronics cavity, the bass made sound as it should.

However, while it is whisper quiet, it does start to buzz as my hand nears the pickup, rests on it, or touches a pole. If I am also touching a string, the bridge, or a pot with my other hand it does not buzz. My understanding is that this is due to the pickups not being grounded properly.

So, what am I missing here? If the pickups need to be grounded via wrapping the foam spacer in conductive tape to connect it with the shielding, but doing so shunts the output of the pickup to ground, how do I ground the pickup?

Thanks!

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2

The pickups already have a ground lead

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Two wires. Hot wire to the volume lug and the black ground wire gets soldered to the back of the volume pot where it ties into the other grounds. That’s it.

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Yeah, and that’s all good. All the grounds test out. But when my hand gets near the pickup or touches a pole, it buzzes. Which, as I understand it, is a grounding issue.

5

Are they wax potted?

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Not sure I know why that means. Does that mean that the bottom of the pickup is “sealed” with wax?

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Yeah the entire pickup between the windings and shell

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8

Oh, no, the poles are open on the bottom of the pickup.

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9

That’s fine if the poles are exposed but you can’t ground anything responsible for creating the output voltage such as the magnets or pole pieces. Is the pickup output ground also tied into the same lead for the cavity shielding?

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10

I reckon you’re the issue here @JustTim
You and your electric personality :grin:

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You are the only one that had the guts to say it @Mac, I was going to suggest @JustTim take up the drums.

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12

:joy:
I meant it in the nicest way possible though :grin:

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13

Sometime it’s just not going to be quiet. Nothing short of checking everything from
Bridge
Cavity
Pots
Pickguard
Wires
Pickups
And strings

The good news is you don’t hear them while you play because it’s a white noise . I had to deal with this quite often on some bass I modded, at one point I just bypassed the whole passive pickup and go active pickup like or exactly EMG. They are pain free and noiseless. I’m not a guitar player so I don’t automatically turn the volume down after the song.

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What happens if you remove the pick guard alltogether (if it’s possible) ? Any difference ?