Non-functional tone pot.

Discussion in 'Pickups & Electronics [BG]' started by rrybicki, Dec 19, 2012.


  1. rrybicki

    rrybicki Supporting Member

    Joined:
    Sep 10, 2003
    Location:
    Cleveland OH / Guangzhou PRC
    Hi All,

    I have a very nice Kramer DMZ 4000 that I am inordinately fond of. Unfortunately, for some reason the tone control seems to be not functioning at all. I have checked the control cavity and not found anything amiss. The tone pot seems to be working, using my meter I found a smooth range from 0 to 515 K ohms.

    Any ideas where to look next? The caps, perhaps? And how could those be troubleshot (troubleshooted?)?

    If anyone has any suggestions, I would be very grateful.

    Thanks a lot,

    Russ

    (photo of control cavity...)

    [​IMG]
  2. Jazz Ad

    Jazz Ad Mi la ré sol Gold Supporting Member

    Joined:
    Mar 16, 2002
    Location:
    Reims, Champagne, France
    The link between the ground cable from the tone pot and the bridge ground seems lousy. Is it even soldered? It looks like it's just wrapped.
    The cap may also be shot, although in this case the typical effect is the tone pot acting like a volume.
  3. rrybicki

    rrybicki Supporting Member

    Joined:
    Sep 10, 2003
    Location:
    Cleveland OH / Guangzhou PRC
    Jazz Ad,

    Thanks very much for your help. Although the wires look simply wrapped, they are soldered and the connection is sound. I tried testing what I could with my meter and could not find an open connection anywhere.

    Of course, my electronic skill set is not so strong.

    Should I just try replacing the cap as the most logical next step?

    Cheers,

    Russ
  4. Stone Soup

    Stone Soup

    Joined:
    Dec 3, 2012
    There are three lugs on your tone pot. One is soldered to the body of the potentiometer, the center one is attached to a capacitor and the third one is not used. Is that one touching the body of the potentiometer? If it is, bend it back so it doesn't touch anything. I'm no real an expert, but that is what I would try, first.
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  6. rrybicki

    rrybicki Supporting Member

    Joined:
    Sep 10, 2003
    Location:
    Cleveland OH / Guangzhou PRC
    Stone Soup,

    I double checked, and the open tab is not shorted to the body of the pot. I bent it a bit farther away to be sure. Thanks for the suggestion, though!

    I tried swapping the capacitor with an identical one I found in my parts box. It had no effect.

    Removing the capacitor entirely (leaving the leads open) had no effect.

    Removing the capacitor entirely and jumpering the leads togther caused the tone pot to act as a volume pot, as correctly predicted by Jazz Ad.

    Stumped.

    Thanks for all your help guys, it is appreciated!

    Cheers,

    Russ
  7. Stone Soup

    Stone Soup

    Joined:
    Dec 3, 2012
    [DEL]What you have is basically a P-Bass setup, wiring wise. I would opt to wire it like a P-Bass.

    I don't understand the second capacitor across the two lugs on the volume pot. I could see a resistor being there to change the value of the pot, but not a capacitor. Did you put that there?[/DEL] I found out the second cap on the volume pot is a "treble bleed". It allows highs to bypass the volume control.


    Here is a Kramer diagram for a guitar, but it's the same circuit. It looks like you
    have the large capacitor attached to the wrong lug on the volume pot.
    [​IMG]
  8. rrybicki

    rrybicki Supporting Member

    Joined:
    Sep 10, 2003
    Location:
    Cleveland OH / Guangzhou PRC
    Thanks guys, for all the help.

    I rewired according to the 4-conductor P-bass wiring schematic from Rothstein and all is now good. It's designed for a four lead DiMarzio pickup and series / parallel switching.

    linky

    Thanks again and Cheers!

    Russ
  9. bassart94

    bassart94

    Joined:
    Jan 7, 2014
    Hello Russ,

    Is it possible for you to upload a picture of the finished wiring job? I'd greatly appreciate it.

    -Artur
  10. rrybicki

    rrybicki Supporting Member

    Joined:
    Sep 10, 2003
    Location:
    Cleveland OH / Guangzhou PRC
    Hi Artur,

    I'd be happy to post pics, but the bass is currently at my apartment in Asia, and I am in the US. I will be back over there in early February and can take pictures at that time, if it will still be of any help to you.

    Sorry about that.

    Cheers,

    Russ
  11. bassart94

    bassart94

    Joined:
    Jan 7, 2014
    That sounds great! Thank you so much Russ. Happy new year!

    -Artur
  12. rrybicki

    rrybicki Supporting Member

    Joined:
    Sep 10, 2003
    Location:
    Cleveland OH / Guangzhou PRC
    Artur,

    Sorry for the delay, but I am finally back at my apartment after the New Year. Here is a picture of the control cavity. If you have any questions, please do not hesitate to ask.

    Sorry about my soldering skills.

    Cheers,

    Russ

    [​IMG]

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