Noisy Precision Pickup?

Discussion in 'Pickups & Electronics [BG]' started by DavePlaysBass, Jun 28, 2008.

  1. DavePlaysBass


    Mar 31, 2004
    I have a precision I dropped an NP4 and a Gotoh bridge on a month or two back. After the mods everything seemed fine. However, recently I have noticed a bit of hum when trying to record. For reference I have a Jazz and a Sadowsky that are hum free in the same setup. I can even solo a J pup and get less noise (the J is shielded).

    So I opened her up and shielded from the electronics cativty to under the pickup. I have a metal guard (gold) on top that makes contract with the copper tape all the way around the routes. I also added copper tape under the Gotoh bridge so the the bridge ground wire gets good contact.

    This did not fix the noise.

    Then I replaced the jack with a switch craft which I was supiscious of given it does not "click". Again no success.

    When I play I sometime brush against the E pole pieces with my right thumb. When I do this the noise gets really loud. I have never noticed this on any other bass (at least to this level). Given the sensitivity of the pole piece to being touched, I believe I have a bad pickup? It still measures 10.6k.

    Any suggestions? Should I contact the good people at Nordstrand?

  2. DavidRavenMoon

    DavidRavenMoon Inactive

    Oct 20, 2004
    Reverse the polarity on the pickup.... just switch the two wires that go from ground to hot at your volume pot. That magnet is either shorted to the coil wire, or is close enough to the end that connects to hot, so you hear noise when you touch it.

    Swap the two wires and now that magnet will be closer to ground, and the noise should stop.
  3. DavePlaysBass


    Mar 31, 2004
    Thanks. That makes sense. Will do.

    Also forgot to mention that the noise goes away when touching strings. But everything measures as a short that should (bridge, pots, plate, etc).

  4. DavePlaysBass


    Mar 31, 2004
    I reversed the wires. No success. I cut out the pots and wired straight to the jack. No success. I resoldered everything leaving the wires reversed and it seems the noise is gone. Not sure what happened, but hopefully it is fixed.
  5. spaz21387


    Feb 25, 2008
    Portland oregon
    I have never heard of a p bass humming so eather its a faulty pickup or possibably you should try plugging your amp in to a different outlet. Since its shielded and you checked the ground thats out.
  6. DavePlaysBass


    Mar 31, 2004
    Hum is gone. Something fixed itself this last time thru. It does not add up but I am not going to question the hum free bodacious P bass tone I had going on this morning at church. Off topic but after a lot of messing around I was getting "the tone", hum free I might add, in spades with flat wounds and a P in a 700 seat room. I used to think it was not possible.
  7. Bassamatic

    Bassamatic keepin' the beat since the 60's

    When you changed the pup something got moved, broken, etc. When you re-installed it it got fixed. There has to be SOME balance in the Universe, yes?

    I had one that made me CRAZY until I found a tiny solder blob that had rolled under one of the pots and was shorting the contact to the shield! It was invisible and only found by dumb luck.

    I recently bought a very nice used MIM P, and while changing the pups to some used USA P that I had, I noticed that there was NO shielding in it at all! (It hummed a bit). So, I did a full copper tape and star ground mod and it is now totally totally silent.