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Lesson How to remove the end stop in a potentiometer

Discussion in 'Electronic and hardware generally' started by Alexey, Aug 6, 2015.

  1. Alexey

    Alexey Well-Known Member

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    Hello all,

    For those of us that have accidentally destroyed potentiometers due to levers going out of range I have a solution! I accidentally came across this neat little fix when one of my motors went ballistic during testing and absolutely borked (so bad that even the spelling is broken) a potentiometer. So before I threw it away I had a quick look at the internals of the pot and fount that the mechanism for stopping the pot could be easily circumvented without any drawbacks.


    Totally inconspicuouss potentiometer:
    [​IMG]

    Pry out the backshell clamps so that they release the little devil:
    [​IMG]

    The two pieces:
    [​IMG]

    The large tab on the top of the plastic is what stops the pot from turning all the way around:
    [​IMG]

    Cut that right the hell off:
    CAUTION: Do not apply pressure the the plastic in any way possible as it can deform the wiper arm!
    If you nibble small sections at a time it will be fine.
    [​IMG]

    After cutting off the tab visually inspect the potentiometer to make sure that it operates correctly and that the wiper arm stays in contact though the whole turning range and that no other part of the wiper arm touches the pad. The only part of the wiper arm that should touch the pad is the bent tab (very technical name).

    Reattach the backshell, have a beer and contemplate how awesome your newly unbreakable pots are.




    Too bad they are still cheap and nasty.
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  2. Ads Master

    Ads Master

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  3. bsft

    bsft

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    Or just buy a 360 deg turn pot.
    But @Alexey thanks for the info
  4. Alexey

    Alexey Well-Known Member

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    You can still have 360 degree pots with end stops. And then with a 360 degree pot you have to limit the axis travel. Removing the end stop simply ensures that you don't smash the pot by any accidental travel either powered or un-powered.
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  5. bsft

    bsft

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    as said man, I appreciate your tutorial on how to fix a $4 pot from breaking.
  6. mariano68

    mariano68 Active Member

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    Good info, perfect for not having to drive 30 minutes to get a new pot or testing sat and Sundays when I can't get any electronic stuff :cheers
  7. speedy

    speedy Well-Known Member

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    Or ... avoid working with plastic and flatten this metal corner back with a flat screw driver [ for weak metal thickness only ] .

    IMG_0567_zpsob6iciwo.jpg
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  8. Alexey

    Alexey Well-Known Member

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    Yes that is also a good way of doing it, you just have to be careful not to warp the case and make sure that the metal tab ends up being completely flat. It's a bit more difficult than it looks to bend that tab back as it is surprisingly rigid and you also need a way to hold the case down as you hammer the tab back down.
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  9. choclo

    choclo Member

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    Works like a charm!
  10. ferslash

    ferslash Active Member

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    man i have broke like 5 pots and it is super frustating having to re-wire a broken pot... thanks :D:D:D:D:D
  11. choclo

    choclo Member

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    By the way... Such Nail Cutters are like made for it! ;)
    DSC_0496.JPG DSC_0497.JPG
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  12. Tags..(VR)

    Tags..(VR) Member

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    this is fantastic. i wondered why i had to keep recalibrating the pot on the SMC3. thanks for the info. done an done.