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pot testing /pots and caps for fender precision

Discussion in 'Pickups & Electronics [BG]' started by the eskimo, Feb 17, 2005.

  1. the eskimo

    the eskimo

    Feb 17, 2005
    hello all.

    have had a look around and can't find an answer to my questions but sorry if this is going over the same ground again..first posting and all that.

    I think there's a problem with the volume pot on my fender precison - getting some pretty abrupt changes in volume as I tweak it and I want to test it (and the tone pot too) before getting replacements in case it's something else.

    to get a genuine accurate reading from a pot do i need to completely detach it from the other circuitry in the guitar?

    i know how to test the pots but have been getting odd readings and think this might be because it's all still hooked up.

    on a simillar topic, what are your suggestions for pot values/types and cap sizes for a 1989 Japanese Precision. I'm after a fairly low/dark tone so guessing I should stick with the 250k size..currently type A. anyone got strong feelings/arguments for using type B on either volume or tone?

    thanks very much. :smug:
  2. Metal Mitch

    Metal Mitch

    Jul 14, 2003
    Well... if the pot sounds like it's broken, who cares what the resistance value is? ;) Squirt some contact cleaner in there, and if that doesn't fix it just replace it. One of the most frequently recommended upgrades for any MIJ instrument is to replace the pots.

    These days, I go for a traditional tone on my P-bass so I use the traditional 250k pots with a .022 cap. They sound great to me. I used to have a .047 cap with a standard "A" tone pot, but I get a lot more use out of the tone control since switching to the "B" linear taper pot with a .022 cap. YMMV.
  3. the eskimo

    the eskimo

    Feb 17, 2005
    cheers for that mitch..you're right that I should just replace it anyway. the more important part was the recommendations re pot types and cap values so thanks for your suggestions.

  4. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    I'm with Metal Mitch on this one, just replace the darn pot and be done with it. It's not even worth "testing". If contact cleaner doesn't work, just get rid of it. :)

    And "yes", the only way to get an accurate reading on a pot is to remove it from the circuit. Generally speaking.

    As far as the various types of pots, I'd stick with the "A" style if I were you. The "taper" of a pot is very important in its behavior. 250k "A" pots are very common, you can find them just about anywhere, at your local GC or at any one of dozens of online supply places.

    That's where I'd start, and it's just a suggestion, but I'd try to make my bass work "correctly" first, before I'd think about possible modifications.

    As far as the caps go, it depends how much you're willing to invest. My take is, even a "cheap" cap will make a P bass sound good. But, there are many options in that regard. Some people swear by the "poly" caps (polystyrene, polypropylene, and so on). Personally, some of the sweetest sounding caps I've ever heard are the NPO ceramics. But they're pretty expensive, and relatively hard to find. Is it worth the effort? Maybe, if you're really needing the extra increment in tonal quality. But if you're just plugging your bass into a live amp for stage work or at a club or something, my take is, "probably not". Any old cap you can get at Radio Sh*ck will probably do the trick.

    Just IMO of course. My 2c. :)
  5. Thanks, gang. Answered my question.
    5-1/2 years later and this little thread is still helping people (me!).
  6. Growly Lytes

    Growly Lytes

    Dec 4, 2009
    Downunder Oz
    Bass player
    So what would happen if you change the pots from one value to another ? Does it change the sound or output of the bass ??