No sound when grounding bridge

yoan973

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Hi guys,

I shielded my partcaster and I have a real issue with the bridge pickup, a Fender Nocaster 51 by the way. If I touch the bridge or the bridge plate I have a hum. And when I connect the ground wire that is supposed to be flushed between the body and the bridge plate, the hum disappears but the sound too. No issue with the neck position but middle and bridge are muted then… It seems to me that the hot signal from the bridge pickup is somehow connected to the bridge and thus caused hum when I touch or short when grounded but I can’t find where to look or what to do… help please!!!
 

yoan973

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Yes. In fact when I hold the bridge in my hand there is the hum but when I touch the poles with the screwdriver I have the sound then I put it back in place in the pocket and the sound is cut off, the hum too. The grounded wire touches the bridge and it d’osés the same thing even when the bridge is in my hand…
 

yoan973

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Any possibility the switch is contacting the shielding - like at the bottom/sides of the cavity? How is your shielding grounded?
I have a ground wire from each cavity connecting them together and back to a ground spot on the pot.
 

Sparky472

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As others have mentioned, sounds like a hot wire or switch contact somewhere is making contact with the shielding. I’ve had this issue before after adding shielding in particularly tight cavities. Once I was able to find that connection point, some electricians tape on top of the shielding as an insulator does the trick.
 

yoan973

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maybe it will help the process,
When the bridge test on the body, not in the cavity. I connect the jack, I have a sound and no hum on the pickup poles but a buzz when I touch the bridge. And when I make the ground wire touch it no sound or buzz… nothing
 

yoan973

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As others have mentioned, sounds like a hot wire or switch contact somewhere is making contact with the shielding. I’ve had this issue before after adding shielding in particularly tight cavities. Once I was able to find that connection point, some electricians tape on top of the shielding as an insulator does the trick.
Tried the electrician tape all over the cavity but nothing… maybe I have to check it again but even with the tape when I make the grounded wire touch the bridge it’s over… no sound
 

yoan973

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It’s as if the pickup and the bridge is like a big hot signal so when I touch it with the ground the signal is off that is quite logical to me but I wrapped the pickup with electrical tape before I put it in the bridge and still nothing changes…
 

Boreas

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It’s as if the pickup and the bridge is like a big hot signal so when I touch it with the ground the signal is off that is quite logical to me but I wrapped the pickup with electrical tape before I put it in the bridge and still nothing changes…
Pix of the bridge, etc. may help with diagnosis.

Did you have the bridge plate hum PRIOR to shielding? That may be key.

Could you have damaged any wiring when wrapping the bridge pickup with tape?
 

yoan973

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I checked it and the yellow wire is on the switch the black is on the ground. I checked the isolation beteeen the pickup and the bridge the only contact points are the mounting screws for the pickup coils are wrapped with electrician tape. When I touch the bridge with my hands there is a hum…
 

Boreas

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I checked it and the yellow wire is on the switch the black is on the ground. I checked the isolation beteeen the pickup and the bridge the only contact points are the mounting screws for the pickup coils are wrapped with electrician tape. When I touch the bridge with my hands there is a hum…
Is the hum NEW or was it present prior to shielding?

One thing to try is to screw the bridge plate down and leave the control plate off. Then using a continuity tester, check for continuity that shouldn't be there. Obviously there is a short - the trick is finding it! Not much we can do without being there or seeing pix. :)
 
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yoan973

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In fact in the first version of the guitar there were no shielding. I stripped it off, sand and refinish it with nitro. And because I want to use it on stage I decided to shield it.
 

bottlenecker

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It seems to me that the hot signal from the bridge pickup is somehow connected to the bridge

Yes, you have a short. A continuity tester will tell you. Check between everything until you find it. If you just shielded it, it's probably related.
 

yoan973

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I had no issues like that before and the neck pickup was a hum bucket, now it’s a CC pickup. But nothing wrong with the neck for now.
 

yoan973

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Are you certain that your switch is wired correctly?
How can I check further? Because I don’t know much about it. When the bridge is just out of the cavity everything works great except for the hum when I touch the bridge itself not only the pickup
 




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