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crazy grounding idea

Discussion in 'Hardware, Setup & Repair [BG]' started by anonymous278347457, Jan 23, 2006.


  1. anonymous278347457

    anonymous278347457 Guest

    Feb 12, 2005
    I hope nobody has said this already, but i just thought of something which i think might work.


    i noticed that my bass hums a lot if i turn the volume and tone to full. but the hum goes away if i touch a string, tuning peg or the bridge.

    so could it be possible to attach a wire to the bridge/tuning peg and then strap it to your leg/arm.

    then it would get rid of some of the hum.


    is this a good idea? or will i hurt myself or my bass. (im talking passive J+P basses here)
     
  2. Tony G

    Tony G

    Jan 20, 2006
    NY
    There are many methods for noise canceling. Yours is not one of them.
     
  3. anonymous278347457

    anonymous278347457 Guest

    Feb 12, 2005
    damn, it looks like I have to do some shielding then......
     
  4. THIS IS NOT A GOOD PLAN. PLEASE DON'T DO IT.

    There is a fault somewhere that need sorting by a techie. If a ground is missing you can only harm (also = possibly kill) yourself by electrically strapping the instrument to your body.

    Have a guy check the bass by checking the resistance between the ground side of the bass's jack to the bridge and strings. The resistance should be VERY low: a few 100th's of an Ohm perhaps.

    Check the bass to amp cable's screen continuity. Check for VERY low Ohms reading from the ground side of one jack plug to the ground side of the other jack plug.

    Finally, have a techie check the ground continuity between the EARTH pin of the mains plug to the GROUND side of the amp's input jack socket. Have a techie do this cos he'll know what he's looking for.

    I can't stress enough that YOU MUST be ABSOLUTELY CERTAIN about the ground integrity of the WHOLE system. Quite literally, your life may depend on it.

    If that is all OK and you still have trouble the most likely problem is a broken ground wire uderneath the bass's pickguard.

    If that's all OK and there's still problems YOU MUST get the mains outlet checked out for earth continuity, or report the possible fault to someone. Only a qualified electrician can do these tests. Alternatively, plug the amp into a different mains into a different outlet in a different part of the room. A different building might be better if that's possible because you'll then eliminate a possible ground fault in your current building.

    Just take good care with this. Treat electricity with respect.

    John
     
  5. anonymous278347457

    anonymous278347457 Guest

    Feb 12, 2005
    is the ground meant to be going to the bridge?

    because if so i checked the control cavity and there is a white wire coming out of a pot and going to the bridge area. btw, i tried it at my bass teachers house and it still does that.


    also do you mean it will only do damage if i try my crazy grounding idea? since its just an idea i havent done it.
     
  6. Yes. The bridge is meant to be grounded. There were 2 ways of doing this. One is just a piece of wire. The other is a capacitor and resistor in parallel. They both do the same thing but in different ways. But both will behave differently in a simple resistance test: that's why you really need a techie to do the test.

    If your bass still behaves like that at your teacher's house then it's almost certainly the instrument that's at fault.

    Is it a Fender / Squier? If so go to www.MrGearhead.net. That site has all the wiring plans for Fenders (somewhere in the support section I think). It's not uncommon for a control pot to get loose and constant twisting eventually breaks a wire. I wonder whether that might be your problem?

    Yes. You may damage if you try the idea. It'll probably be OK but isn't wise to experiment with earth faults.

    Believe me, I've had 30 years in electronics / electrics / elec safety.

    Get it checked. If it's the bass a music shop should have someone capable of handling the repair.

    John
     
  7. The Rockin' one is absolutely right on...(as usual)

    Here's the reason why not - Just about any current capable of being sensed by your skin is enough to send the heart into fibrolation if it passes through the organ. In the grounding scenario John paints, you would have your left hand on the neck and the right hand in the playing position. If you come in contact with another piece of equipment that is on a different polarity and the voltage will go right through your bass to ground (your feet) choosing the path of least resistance. When the current enters your left hand, it will travel to ground and the other hand. What's between your left hand and your feet? Yep, the ol'ticker. And if that happens, you stand a good chance of injury.

    When you hear a ground buzz, that's NOT a properly functioning circuit. It might be working correctly for what it is supposed to do workwise but there's a flaw somewhere. Don't play around with this stuff unless you are knowledgeable about the dangers.