Strat Wiring Help - pos 4 hums, not 2

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by Greg, Oct 29, 2004.


  1. Greg

    Greg Member

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    Hopefully someone can help me identify a solution. I just got a strat copy from a listmember. (I bought it primarily for the color - yes, I'm shallow.)

    The hum disappears in position 2 (b+m), which suggests that it has a RW/RP middle pickup. But position 4 (n+m) hums just as loudly as 1, 3, and 5.

    I looked under the pickguard, and everything looks to be soldered cleanly, and the solder is nice and shiny. It supposedly has early Fralins in it, and I have no reason to doubt that. (The pickups have cloth wires.)

    So, what can be the problem? Is it a phasing issue? I don't really know what that means.

    Thanks for your help,
    Greg
     
  2. Jim Collins

    Jim Collins Member

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    If the hum disappears in the bridge+middle position, it suggests that ONE of those two pickups is RWRP. If you also get hum in the neck+middle pickup, this would seem to indicate that it is the bridge pickup that is really RWRP, with respect to the other two pickups. RWRP is not an absolute; it is relative. A pickup is RWRP with respect to another pickup. If someone orders a normal bridge pickup, with two RWRP pickups for the neck and middle, then it is really the bridge pickup that is RWRP with respect to the others. Perhaps the original plan was to wire the guitar so that the positions 2 and 4 yielded the neck+bridge and middle+bridge combinations. Those would be hum cancelling, if the bridge were RWRP with respect to the other two pickups.

    Phase problems are different. If two pickups are out of phase with each other, when the two pickups are combined, as in the 2 or 4 positions, the resulting sound will be thin, very nasally, and weak. Does this sound like your 2 or 4?
     
  3. Greg

    Greg Member

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    Thanks, Jim.

    That makes perfect sense. How would one be able to determine whether 2 pickups are RWRP from each other?

    I don't think 2 and 4 sound thin or nasally. At least the volume doesn't drop from 1, 3, or 5.

    Greg
     
  4. Jim Collins

    Jim Collins Member

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    If neither position 2 nor 4 sounds thin and nasally, then you do not have a phase problem. You probably have a guitar whose bridge pickup is RWRP with respect to the others.

    If you had a compass, and point to the pole pieces of each pickup, you could tell. Failing that, loosen the strings enough so that you can remove the pickguard assembly, with the pickups still on it. You do not have to remove the strings for this, and you won't have to wield a soldering iron for what comes next. Simply unscrew the pickup mounting screws, and remove the pickup. (Don't unsolder.) Hold that pickup, face to face, with another pickup. If those two pickups attract, they have opposing magnetic polarity. Armed with this knowledge, you can easily test.

    If pickup A is attracted to pickup B, and A is attracted to C, then A is RWRP with respect to the other two.

    If pickup A is attracted to pickup B, and A is not attracted to C, then pickup B is RWRP with respect to the other two.

    If pickup A is not attracted to pickup B, and A is attracted to C, then C is RWRP with respect to the other two.

    If pickup A is not attracted to pickup B, and A is not attracted to C, then all three pickups have the same magnetic polarity, and none is RWRP.
     
  5. alderbody

    alderbody Member

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    I agree with Jim, but i would check something else, too.

    remove the pickguard and flip it so to see the back of it.

    take a close look at the hookup wires that come out of the pickups.

    Normally, you should see a black and a white(off-white) cable on each pickup.

    If one of your pickups is RW/RP, it's cables should have an opposite polarity.
    This means, if the other two have, for example, the black wire at the left and the white at the right, this one should be the opposite.

    If this happens, just put the RW/RP p/u in the middle position and of course reconnect the cables to the correct tips, and the problem should be gone!

    good luck :)
     

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