Shielding question on MIJ Jazz

Discussion in 'Pickups & Electronics [BG]' started by ghindman, Mar 1, 2006.

  1. ghindman


    Feb 10, 2006
    So, I've got some random humming, crackling from my MIJ Jazz bass - not the usual single-coil hum, but grounding issues - touch the bridge/strings, goes away, etc..

    I was going to put on some new strings, so I thought I'd crack the control/pickup cavity and see what was going on in there, shielding wise, and I came across something very odd.


    The control cavity and each pickup cavity have a strip of copper plate across the bottom that is rudimentarily star-grounded to the neck-pickup volume pot.

    So, my questions are are these:
    1) Is this the factory configuration for MIJ fenders, or has a previous owner futzed with it?

    2) If I complete the shielding around the sided, and do a proper star-ground to a lug, am I going to see much difference in noise?

    3) If you look closely in the pic, the pickup cavity pieces of copper have a strip of foam across the top that the pickup sits on - there's no other mechanism providing tension against the pickup screws, and I'd like the pickups a bit higher than the foam will allow - am I safe in just shimming up the copper plate?

  2. momo


    Oct 22, 2005
    Huntington Beach, CA
    This is the same config used on the Geddy Jazz, and I think it is quite effective, although not ideal. I don't think you would get a WHOLE lot less noise, but it couldn't hurt. Some GL owners have noted the shileding/ star grounding benefit.

    As for the copper, I would add foam ABOVE the copper, on top of the other foam and beneath the PU. That copper plate acts as a shield, so it is best against the wall of the rout.
  3. ghindman


    Feb 10, 2006
    good call on the foam on top, thanks - my brain's obviously not firing on all cylinders, tonight.

    Yeah, I may just clean up the wiring and put in a star ground that's not soldered to the pot case and see where I'm at. I can't believe how thing the pickup leads are - maybe 22g, maybe.
  4. ghindman


    Feb 10, 2006
    So, I think my plan is to get my hands on some conductive shielding paint, and paint the cavities - the existing ground plate should contact the paint adequately - and then just redo the star ground to a ground point, rather than to the pot.