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Extremely Low Volume after applying shielding paint

Discussion in 'Pickups & Electronics [BG]' started by jergato, Aug 19, 2007.


  1. jergato

    jergato

    May 21, 2007
    I recently applied shielding paint in the body cavity of my Fender Deluxe Active Jazz Bass. It is a mexican made guitar with active electronics. It has Fender noiseless pickups and obviously, a 9V battery compartment. I also desoldered the ground wire from the pot shell (mid control) and created a common ground point and soldered an extension from the star connection to a terminal connection on the cavity wall. I removed the bridge ground wire as well.

    My problem is that it is almost impossible to hear. To get any signal at all, I have to crank the volume and all tone controls to the max, including my amp. The blend pot works fine. It provides the same blend control that was present before the shielding.

    I thought I remember reading somewhere that active electronics require a different grounding scheme. Do anyone have any experience or insight to the described problem? It would be much appreciated.
     
  2. figuredbass

    figuredbass Supporting Member

    Jul 11, 2007
    NYC vicinity
    You either have a short, where the signal has accidently come into contact with the ground via the shielding paint, or your change in the grounding scheme has caused a lack of continuity in the overall signal. I suggest checking the following:

    1. Assuming you also applied the paint to the pickup cavity, make sure that the pickup leads (the hot signal one in particular) are not actually in contact with the shielding paint in the pickup cavity. Most Fender pickups are not sealed and therefore not insulated, and the pickup leads at and near the pickup's solder terminal are exposed where they could come into contact with the grounded shielding paint, creating a short. You may have to insulate these terminals from the paint using a hard, thin sheet of plastic. Don't use electrical tape as the pickup terminals can easily cut through the tape when screwed down.

    2. Make sure none of the lugs of any of the pots are touching any areas of the control cavity where shielding paint has been applied - this will also cause a short. Also check any other exposed electronic connection points to make sure they aren't touching the shielding paint either. This includes the tip connection of the output jack, preamp connections and battery terminals. You may even need to insulate the battery itself from the paint.

    3. Re-check your "new, improved" grounding scheme - maybe it isn't! There may not have been any real reason to change it, and you may have disconnected something you shouldn't have or shorted something.

    4. Check to see that ALL wiring connections are still intact, with no loose or disconnected wires, including those on the pickup. Sometimes when doing a job like this wires can become disconnected or shorted.

    Hope this helps you find the problem.
     
  3. jergato

    jergato

    May 21, 2007
    Thanks for the detailed response. After fiddling with the jack, I was able to receive normal signal strength. I discovered the hot lead from the jack was coming in contact with the shielding paint. I insulated the connection with tape to separate this connection and I was back in business.
     
  4. figuredbass

    figuredbass Supporting Member

    Jul 11, 2007
    NYC vicinity
    Great!
     
  5. T. Brookins

    T. Brookins Supporting Member

    BUT
    PUT THAT BRIDGE GROUND BACK ON!
     

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