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Need help identifying a potentiometer

Discussion in 'Electronic Components' started by bryanska, Dec 26, 2006.

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  1. bryanska

    bryanska Guest

    Hello, I pulled a part from my stereo that needs to be replaced. I
    figured it was the potentiometer, because the sound was crackling.

    When I pulled the assembly, it was TWO potentiometers, linked together.
    There is a shaft running through them. I don't have ANY idea where I
    can find a replacement. The JVC repair site lists the larger assembly
    at $59.

    I have posted pictures on my website, in the links below.

    Please help me identify these two pots, and any tips on where I can
    find replacements. I will be VERY grateful.

    Also, how can I tell which replacement pots to buy? I don't see a
    universal code that tells which voltage/etc., like resistors have.

    http://www.theevilwebsite.com/blog/_archives/2006/12/26/2598747.html

    http://www.theevilwebsite.com/blog/_archives/2006/12/26/2598750.html

    http://www.theevilwebsite.com/blog/_archives/2006/12/26/2598751.html

    http://www.theevilwebsite.com/blog/_archives/2006/12/26/2598756.html

    http://www.theevilwebsite.com/blog/_archives/2006/12/26/2598761.html
     
  2. bryanska

    bryanska Guest

    OK I see that these are dual-gang pots. I found that out.

    But there are two linked together? Where can I find those?

    Also, why does on pot (the forwardmost one) have only one set of three
    pegs?

    And I haven't found four-pegged pots, like the one in the rear. Why
    does it have four?

    Again, any help is welcome.
     
  3. Dave Platt

    Dave Platt Guest

    It's probably custom-fabricated for this particular product. The
    individual subsections are probably not all that unusual, but the
    combination is likely unique to this one product line.

    The two four-contact sections are probably a pair of linear-taper
    potentiometers with a fixed tap (the tap being used for the "loudness"
    circuit). The three-pegger in the front might be a switch, or might
    be a linear-taper pot which is used to read out the control's
    rotational position so that the remote control management circuitry
    can "servo" the pot to the desired location.

    You might want to try giving each of the potentiometer sections a good
    cleaning, using a low- or no-residue contact/control cleaning spray,
    or perhaps one which is designed to clean the contacts and then leave
    a very small amount of lubricant on the potentiometer surface. This
    *might* restore the control quality enough to get rid of the crackly
    sound.

    If that doesn't work, and if you decide that you do need to replace
    the control, I think you're probably going to have to just buy the
    whole replacement module from JVC for their asking price. Although it
    might be possible to cobble together a custom replacement from
    off-the-shelf parts, I think that you'd probably have a very
    frustrating time indeed trying to put together the necessary set of
    components, and would likely have to do enough adaptation and
    refitting that you'd end up with a basket of snakes.
     
  4. How hard did you pull it, exactly? That bent and broken metal looks like a
    lost cause to me. Cleaning the pots with a small flush of isopropyl alcohol
    might have been all that was needed, but now you'll need the original
    assembly complete with the mounting bracket to get things right. You might
    find a pair of dual-ganged pots on one shaft, and use half of one of them,
    but you'd have to get a A law (log) pot for audio, and if you wanted the
    remote volume control to work, you'll have to figure out a way to get the
    gear attached and connected to the motor drive, and a flat on the spindle
    appropriate to the original knob.

    Beleive me, pay what JVC want. It's far easier to raise that money than to
    make this work any other way. Pay it and don't look back.
     
  5. Looks to me as if it is a custom assembly. There may be four
    resistance elements (the brown wafers), interconnected in some special
    way.

    I expect that the only source for a direct replacement would be JVC.
    If you had a wiring diagram for the stereo, and sufficient knowledge,
    you may be able to find a usable substitute, but it likely wouldn't
    work quite the same, and probably couldn't be motor-driven.



    --
    Peter Bennett, VE7CEI
    peterbb4 (at) interchange.ubc.ca
    new newsgroup users info : http://vancouver-webpages.com/nnq
    GPS and NMEA info: http://vancouver-webpages.com/peter
    Vancouver Power Squadron: http://vancouver.powersquadron.ca
     
  6. bryanska

    bryanska Guest

    How hard did you pull it, exactly? That bent and broken metal looks like a
    Thanks for the advice all.

    I searched ALL over the Net and couldn't find any generic part close to
    this.

    I wasn't concerned about the bent metal. That was an easy "loss" which
    allowed me to gently pull the delicate pieces apart.

    So I dissected it, having given up on finding a cheap replacement. It
    was indeed very custom, as the shaft proceeded through the first pot,
    and through the second, to terminate in the gear assembly.

    I am going to try to contact a representative at the JVC parts house
    and fanagle a lowball offer on the assembly. The stereo itself is an
    older model built in 1991. My father paid an exorbitant sum and kept
    the unit in flawless shape. It's a shame that some tiny, otherwise
    cheap copper contacts will bring down what's really a glorious system.
    It was one of the first "shelf" size systems.

    Thank you everyone for your advice! What a helpful group.
     
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