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Grounding Problem!

Discussion in 'Pickups & Electronics [BG]' started by Hevy T, Oct 9, 2013.


  1. Hevy T

    Hevy T Supporting Member

    Jan 11, 2011
    Lethbridge, AB Canada
    I bought an Ibanez SR 375 last week. It has a bad hum that goes away when you touch the strings, however when you let off on the strings it is right back there. Here is the message I got from the tech who is working on it. I am confused!

    "I looked at the bass. Hum goes away when touching strings. This means that circuit, bridge, & strings are grounded properly. The cavity is shielded and all the wiring look fine. All the frets are level but I adjusted the truss rod to get rid of fret board buzz. I also smoothed the fret ends, they were pretty sharp. You can pick up the guitar tomorrow if you like."

    Any help would be appreciated.
     
  2. JasonLamb

    JasonLamb

    Aug 17, 2007
    It needs to be shielded with copper tape or a good shielding paint...factory shielding is usually not enough.
     
  3. uOpt

    uOpt

    Jul 21, 2008
    Boston, MA, USA
    If it gets better when touching the strings the internal (electronics cavity) shielding isn't good. But that is normal.
     
  4. Sometimes it is easy to sheild the cavity, but forget to ground the sheilding. Make sure that the foil (or concuctive paint) has a solid electrical connection to the outer ring of the output jack. Same for the foil on the back of the pickguard. I had this same problem with conductive paint before. A woodscrew, a ring crimp lug, and a wire to the jack fixed the paint sheilding. Foil type sheilding should have a ground wire soldered to it, or be mechanically clamped down when a switch,or pot, or output jack, tightened down.
     
  5. OP,
    If the hum is a B, it is a 60 Hz hum. Unless you want to go the shielding route, I'd recommend buying an ElectroHarmonix HumDebugger. Works great for myself.
     
  6. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism Supporting Member

    As others have said, you have a shielding issue, not a grounding issue. The shielding is either not grounded or loses continuity somewhere. Most techs think that 60hz hum is not an issue, heck even some major manufacturers don't (See: Fender), it is definitely an issue that needs to be corrected. Give the bass a shielding job and the issue will be resolved. I do not recommend an external fix for an internal problem.

    Do not pay a tech for a shielding job, it will cost you considerably less to buy a soldering iron and the parts required than it would for the hour of tech time.
     

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