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Tone Pot Lugs Question

Discussion in 'Pickups & Electronics [BG]' started by Lyle Caldwell, Dec 28, 2004.


  1. Lyle Caldwell

    Lyle Caldwell

    Sep 7, 2004
    Memphis
    I notice that Fender wires the tone pots on 62 RIs so that the center lug is jumpered to the outside lug that's not used in most tone pot wiring schemes.

    Does anyone know why? What's different in a circuit with that lug connected to center vs leaving the lug unconnected? Thanks.
     
  2. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    Don't know but I'm guessing Dharmabass or RyanHelms will and you can email/pm them. I know Fender has used a cap tieing input and output lugs on volumes so treble doesn't bleed off when volume is at low setting but it probably has something to do with the sweep.
     
  3. Lyle Caldwell

    Lyle Caldwell

    Sep 7, 2004
    Memphis
    A guy in the pit just answered. It doesn't do anything but assure a connection if the wiper doesn't make contact with the carbon track. Odd that I've only seen in in Jazzes, though I haven't looked inside a Jazzmaster or Jaguar in a while. Fender didn't do it with Strats, Teles, or P Basses, and stopped on Jazzes.
     
  4. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    That thought had crossed my mind but it doesn't flow logically cuase as a manufacturer you don't do things like that as a precaution becuase it's not cost effective. I believe there probably is a tone related reason because I recall on the old Bart TCT diagrams they showed the same thing on the bass pot cuase I wired a few up. I don't recall seeing that on any other diagram I wired from.

    By the way, that volume deal mentioned previously was on a Tele.
     
  5. RyanHelms

    RyanHelms

    Sep 20, 2003
    Cleveland, OH
    I'm staring at the '62 reissue wiring and I don't see the benefit, or what (if any) difference there would be - the signal is sent straight through the cap to ground at full counter-clockwise rotation, and "sees" the taper the correct way, same as any other tone control.

    What *is* the reason for the loop from lug 2 to lug 3? If the wiper doesn't make connection with the track you're left with the pot's full resistance in series with the cap to ground which is the same as the pot turned full clockwise. Wouldn't that be true with any other tone pot wiring variation?

    Now I'm bugged - there really doesn't appear to be any electrical difference whatsoever with respect to whether the outer lug is tied to the wiper or not. So much for my "understanding" of guitar wiring... :confused:
     
  6. Lyle Caldwell

    Lyle Caldwell

    Sep 7, 2004
    Memphis
    I feel your pain. It made no sense to me, either.
     
  7. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    Well I've taken a tone and volume pot and ran a meter going both ways and I can't tell any difference.
     
  8. Isabigload

    Isabigload

    Nov 28, 2004
    Bwad
     
  9. Tim__x

    Tim__x

    Aug 13, 2002
    Alberta, Canada
    It's doesn't do anything here, whoever designed it probably was an EE connecting the two lugs out of habit, in some circumstances it is very important that a (trim) pot doesn't open, think exploding transitors.
     
  10. RyanHelms

    RyanHelms

    Sep 20, 2003
    Cleveland, OH
    So the jury is in - there's no difference with respect to the function of the low pass filter, i.e. tone control. That was my hunch, "good EE practice", but I was unsure enough to keep quiet. Funny how someone's common sense habit can become a source of mystery and conjecture...

    Thanks for chiming in Tim_X.
     
  11. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    in thinking of the Bart diagram, I skimmed through their other diagrams and noticed that that bass pot in the TCT diagrams was the only diagram with a pot that would have no connection to a lug otherwise. Even though a bass manufacturer would not likely engage in such a practice, it would make sense that someone specializing in aftermarket preamps would.

    Being who he was, I'm guessing Leo operated on a similar plain. It's interesting that Fender (CBS or whoever they were at the time) would go into that kind of detail with the re-issues - although it seems the re-issues were made in Japan which whould explain that aspect.
     
  12. Lyle Caldwell

    Lyle Caldwell

    Sep 7, 2004
    Memphis
    This is the American Vintage bass. The MIJ/CIJ 62 RIs had three pots, not stacked. I don't have a schematic, but I owned one years ago, and its tone pot was wired "normally".