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source of replacement potentiometer

Discussion in 'General Electronics Discussion' started by gothictoss, Sep 29, 2020.

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  1. gothictoss


    Sep 29, 2020
    Hey all,

    I have owned a NAD C326BEE stereo amplifier for a few years now, more recently there has been some loss of the left channel / crackling when adjusting the balance potentiometer, i assume replacing this should restore full functionality.

    Checking the online service manual below indicates the part to be a "VR ROTARY POTENTIOMETER 20KMNX2 L=20mm W/CCRV16A01F-20-20F-MN20K-3C (RoHS)", but google is bringing up no exact matches for the term, and i dont know which partial matches would be compatible.

    Would you have any suggestions where i might source this potentiometer? I mean ultimately the handle length is not important, and i really dont intend to ever use the balance adjustment, so the steepness curves wont matter either. Just a replacement to set equal balance and ignore for years to come, without the channels crackling.

    Thanks for any assistance you can provide.
  2. Bluejets


    Oct 5, 2014
    You might try giving the interior of the pot (if accessible via the terminals) a squirt with contact cleaner ( or crc...wd40) first.
    A good spin back and forth a few times after that usually clears the problem.
  3. gothictoss


    Sep 29, 2020
    Thanks bluejets. I had already taken it out of the system, but can certainly try giving the internals a clean and re-soldering.
  4. Alec_t


    Jul 7, 2015
    If you intend to have only a 'set and forget' function you could just replace the pot with fixed resistors, or even by-pass the pot altogether.
  5. shrtrnd


    Jan 15, 2010
    How's about looking at the characters written on the pot itself, maybe a manufacturer name or logo.
    Odds are, it'll help narrow-down the search for an exact replacement.
  6. gothictoss


    Sep 29, 2020
    Thanks for the response, the are a few bits of info on the pot. Alpha, M20K, ON3.

    This seems very close to the ebay model identified by Bertus, dual with centre detect, I wonder if I can now find something similar in the UK. No D handle, but I can't be too fussy.

    perhaps the below would work?



    Dec 19, 2019
    Did you try Bluejets suggestion and spray it to clean it? I recently used WD-40 to fix scratchy sound on bass amplifier - fixed. Volume on electric guitar - fixed. Tone control on friend's stereo - fixed. Of course I spray all switches and controls once I'm inside the unit.
  8. Nickelmore


    Dec 5, 2020
    Did it work out for you? I have the same model and the same problem.

    I'm thinking about by-passing the pot anyway. What kind of resistor do I need for this?
  9. poor mystic

    poor mystic

    Apr 8, 2011
    Did you try the WD-40 trick? Should be good for a month or 2
  10. Nickelmore


    Dec 5, 2020
    Yeah, tried it with potentiometer cleaner (Kontakt Chemie Tuner 600) and it seemed to just move around the dirt inside the potentiometer. The crackling/drop outs moved from the one speaker to the other.

    I've managed to bypass the balance potentiometer with 4x 10ohm resistors, and it was working fine in a first run. Going to test it in a week if everything is fine now.
  11. Phil_Fr


    Jan 9, 2021
    Hi Nickelmore,

    I am facing the same issue with my amplifier Nad C326 and I am now considering to bypass the balance potentiometer by resistors just like what you did.
    Could you please explain a bit more in details how you did that as there is 6 pins hence you would need 3 resistors instead of 4 (per your reply).
    Ps: sorry for typo...I’m French :)

    BTW, I also tried to clean with WD40 but it worked just for a couple of days.
    Last edited by a moderator: Jan 9, 2021
  12. Nickelmore


    Dec 5, 2020
    Hi Phil_Fr,

    my father did this and i tried to follow it - but I'm not an electrician. And I hope to remember it correctly: He bypassed the outter pins twice with 10ohm resistors

    1 - 2 - 3
    4 - 5 - 6

    from 4 to 1 (1) and to the connection (2)
    from 6 to 3 (3) and to the connection (4)

    I hope this is useful in any way :D
    We had to drill a hole so the potentiometer fits in a 90° degree in the case and the regulator stays in place (even though the top point is not upwards anymore ;))
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