Gibson HB-L PCB Pickup

[Axl]

I have one of these that has hum. Upon popping the cover, I notice that the PCB has a copper foil coating on the inside.

This copper isn't grounded. The only thing touching this copper is the magnet that lies on it. That means the magnet isn't grounded either. Why would that be part of the design?

Aren't the backplates of most humbuckers grounded?

 

[super rad stuff]

Re: Gibson HB-L PCB Pickup

i'm not totally sure but i think the copper foil should be grounded. the magnet is never soldered to be grounded. is your pickup 4 conductor? and is there a braid from the conductor soldered to the plate? what kind of hum are you getting from the pickup, more of a buzz or a ringing hum?

 

[Axl]

Re: Gibson HB-L PCB Pickup

It's 4 conductor. It has a buzz. The buzz gets quieter when I touch the copper foil or ground. Ohm meter shows no connection between foil and ground though. It's strange.

The shielded wire is soldered to the ground pad and pickup cover.

I have these pickups wired up in a Washburn WI-64. It has that VCC wire scheme, so who knows.

 

[super rad stuff]

Re: Gibson HB-L PCB Pickup

sounds like you've got a grounding issue. make sure your bare wire is securely soldered to the baseplate of the pickup and to the bridge ground, and carefully ground the foil to the baseplate. as long as all of your pots are grounded together, there shouldn't be any more buzz.

 

[DonP]

Re: Gibson HB-L PCB Pickup

That foil should probably not be there.

Post some pictures...

 

[Axl]

Re: Gibson HB-L PCB Pickup

sounds like you've got a grounding issue. make sure your bare wire is securely soldered to the baseplate of the pickup and to the bridge ground, and carefully ground the foil to the baseplate. as long as all of your pots are grounded together, there shouldn't be any more buzz.

The baseplate IS the foil.

Well, the baseplate is a thick circuit board with thin copper on one side.

I soldered a solid strand jumper wire from the ground pad to the foil.

It killed 90% of the buzz in the bridge pickup.

I just noticed that the magnet poles of the neck PU's are different on the stock PU's from the Gibson PU's

The adjustable pole pieces of both, the stock and Gibson neck PU's attract each other when putting them face to face with each other. That means one PU has a south pole orientation on the adjustable side and the other has a north pole orientation on the adjustable side.

I thought most all PU's had south pole on the adjustible pole piece side.

http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=color_codes

On the stock and Gibson bridge PU's, the adjustible poles repel each other when placed face to face. I am thinking they are both south pole oriented on the pole pieces, which would be correct.

I don't know if the stock neck PU is a mistake from the factory, or if that's the way it was designed for this VCC wire scheme, or what.

Would any of this be making the Gibson neck PU buzz?