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Loose wire in cavity

Discussion in 'Pickups & Electronics [BG]' started by Gnermo, Nov 14, 2012.

  1. Gnermo


    Jun 1, 2011
    Hello everyone.

    I've bought a Schack bass the other day and it played AND sounded absolutely amazing.

    But somehow I managed to screw it up by disconnecting a wire, accidentally pulled out the PCB a bit too hard.
    So now it produces no sound with the batteries in, it does when you unplug those, sans for a huge plopping sound when you use the toggle.
    I tried to figure it out by connecting the wire to the volume and balance put on the pegs or top, nothing happened.

    Here's some pics:

    Anyone have ANY idea where this wire is supposed to go? (And maybe you guys could use some more pictures)
    Schack doesn't reply to any e-mails and I think he went out of business.
  2. megafiddle


    May 25, 2011
    Possibly it was connected to the case on that control pot (upper right in photo)

    Is that a short little wire end hanging off of the pot case?
  3. ringy


    Jul 27, 2009
  4. mech

    mech Supporting Member

    Jun 20, 2008
    Meridian, MS, USA
    I'll start by saying that I don't know if the above diagram is for your bass, but if it is....

    It looks like the wire is #18 per the wiring diagram. If no other wire from the connector is soldered to the body of the blend pot, another pot or jack ground to furnish ground to the preamp, that's where it goes. According to the diagram, all the pot bodies should be grounded.

    BTW...that's some tacky looking soldering.

  5. ringy


    Jul 27, 2009
    The wiring diagram refers to the connections for the Schack BC-3-P EQ PCB rather than anything model specific so I would be confident using it as a guide.

    I ran the pdf through a translation engine, wire 18 (which the loose wire appears to be) is indeed the ground for the PCB and should be soldered onto a pot body or some other suitable grounding point. I can't see any grounding wires between the pots, it's relying on the copper shielding to provide the grounding circuit.
  6. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    And if you look how oxidized that foil is, I'd go ahead and run some ground wires between the pots.
  7. Angel LaHash

    Angel LaHash

    Aug 24, 2012
    its basicaly a filter system .. looks like a nice design.. ill have to scrable the PDF file via Google and see if it can translate it a bit more for myself

    always wanting to get teh most out of any thing i make
  8. ringy


    Jul 27, 2009
    Google translates the text but doesn't show the wiring diagram itself or rather shows it but without the lines indicating the wires!
  9. Gnermo


    Jun 1, 2011
    That could well be it. I tried connecting the wire to that pot while having it plugged in but it still gave me no sound however.

    There is however a small grey wire connected to the side of the orange wire, but it ends halfway. Could the orange one also be #1?

    Would it hurt not to do this? The bass has been operating fine for years now, it's built between 1995 and 97.
  10. iiipopes


    May 4, 2009
    If the pots have never been touched, and they use lockwashers, then the lockwashers have indented into the foil, which assuming there was no oxidation to begin with, would seal the foil and make an acceptable connection for the time being.

    However, once the pots are loosened, as may be the situation when this odd wire is chased and properly connected, then oxidation starts, and the grounds should all be soldered properly as set forth above.
  11. ringy


    Jul 27, 2009
    The problem is we're all guessing here, never going to get a clear view of what's going where in a photo. Gnermo, I think what you need to do is go through it thoroughly, wire by wire, and see where they go. #1 = neck PU hot, #2 = bridge PU hot, the rest are fairly obvious even from the German diagram. Also, I'd consider checking the continuity of all the wires from the PCB, if you managed to break one connection it is quite possible that there may be other wires damaged even if they look OK, ie a break within the insulation.

    I agree with iiipopes, if the pots have never been disturbed then grounding through the foil should be ok. Personally I would use a circuit tester just to make sure.
  12. Angel LaHash

    Angel LaHash

    Aug 24, 2012
    but it dose say what Freq each switch dose, and isnt that just a Resistor and Cap to change that frequency of each part