Wiring troubles (again!)

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by KaBudokan, Nov 17, 2005.

  1. KaBudokan

    KaBudokan Supporting Member

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    Well, I got the guitar wired up, and unfortunately (but predictably), I am running into problems. I wired everything up (the same as I did before, when I twisted the wires together and it worked fine!) and when I plug a cord in I get no signal at all.

    From what I understand, this means that my hot is connecting to ground somewhere.

    Here's a (very bad!) diagram of my setup:

    [​IMG]

    The DPDT should coil tap the two buckers. I also forgot to draw on the ground wire coming from the bridge.


    The only thing I can think of that's different from my mock-up (which worked) is that the cavity is shielded. Is that causing the problem?

    Also, I do have a multimeter, but I have no idea what readings I should be looking for - for example, when I touch a hot connection to a ground (on the output jack, for example), what should it read?

    Thanks for any help... I'm frustrated. (Compounded by a few issues I've had on the finish lately - mostly from my clumsiness - a chip, and a small burn from the soldering iron - D'OH!!!)
     
  2. Jim Collins

    Jim Collins Member

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    Tell me about the point of view of this drawing. Are you looking at it from the point of view of the control cavity? In other words, are we looking at the backs of the pots? If so, your pots are wired backwards.

    This is the major problem with those Duncan drawings. They show the pots upside down. Let's orient the pots correctly. Assume the shaft is pointing toward the floor, and the three lugs on the pot are pointing toward you. The lug on the left will be lug #1, and the lug on the right will be lug #3. Lug #3, on the volume pot, is the one that is supposed to be bent over, and soldered to ground. (This should be done for each volume pot, rather than running a lead from that lug to a different pot.) How are the pots oriented in this drawing?

    If your wiring is, indeed, backward, you should get no sound with the pot full on, but some sound when you back off on the volume.
     
  3. KaBudokan

    KaBudokan Supporting Member

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    You're right - this point of view is looking at the bottom of the pots, with the shafts pointing toward the floor.

    Got it now - everything seems to be working just fine!

    I did take another look at the SD diagram - their diagram makes sense, I just didn't adjust for the pots being upside down (which is not how they are shown in their picture). Not exactly user-friendly, but their diagrams are clear.
     
  4. Jim Collins

    Jim Collins Member

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    Yes, the hot wire from the pickup goes to lug #1, and lug #3 is bent over and soldered to the casing. This is only for the volume pots. The tone pot does not have a lug bent over.

    Your tone pot is wired backwards, also. The output from the switch goes to lug #1 of the tone pot, and lug #1 from the tone pot also goes to the output jack (the tip lug).

    I don't see a tone capacitor in your diagram. The tone cap should go from lug #2 to ground. The easiest way to do this is to go from lug #2 right to the tone pot's casing. The tone pot casing, like all the pot casings, must be grounded.

    If your controls are mounted to a metal plate, the grounding of the pot casings is automatic. If your controls are mounted directly to wood, or to a pickguard that does not have a foil backing, you'll have to ground the pot casings, yourself. Simply run a wire that touches all three casings. Frequently, this is a bare wire that is soldered to the side of each pot, but you can use an insulated wire between pot 1 and 2, and another between pot 2 and 3.

    Another word about wiring. Notice in your DPDT switch, where you have a wire from #3 going to ground, and another going from #6 to ground. The pros would use one wire, stripped a little long on one end, and solder that end to both #3 and #6.
     
  5. KaBudokan

    KaBudokan Supporting Member

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    Thanks Jim. I think you posted your reply right as I was editing my previous post.

    I didn't switch the wiring on the tone pot, because when I switched the wiring on the volume pots and then plugged in, everything seemed to work fine. This is all being done on a body only - the neck isn't on the guitar yet - so when I say "everything is working fine" I mean that the signal is coming from the right pickups at the right time, and that everything seems to be switching correctly.

    I'll go ahead and switch the wiring on the tone pot just to be safe. Might as well do it right... (I don't know if it is affecting the tone at all..)

    I do have shielding paint in the cavity, so all 3 pots are grounded through that. I've heard mixed feelings abotu shielding paint, but it seems to be conducting fairly well here.

    I do have a capacitor coming off lug 2 in the tone pot (just didn't add it to the diagram). Also, I do have one wire connecting the two bottom lugs of the DPDT, as per your suggestion the other day.

    Again, thanks - you've been a great help! :dude
     
  6. Jim Collins

    Jim Collins Member

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