False Y endstop

Discussion in 'Calibration, Help, and Troubleshooting' started by Jean VISCONTE, Oct 12, 2016.

  1. Jean VISCONTE

    Jean VISCONTE Member

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    Y endstop is sometime erratic, once a couple of day typical.

    Autohome starts, and suddenly, without any visible reason, X axis is going to the left, autohome process with an offset from center of bed...
    As a result, zero is false, then head crashes in the back full sped, even making recently one of the Y belts to be disassembled.... annoying isn't it?

    I imagine a glitch on the Y endstop cables which form a loop around the X stepper, but the X stepper is not running when this happens, only Y. Can also be another glitch source.

    I also imagine some bug in the firmware

    Does this sound familiar to anyone?

    Many thanks
     
  2. Kanedias

    Kanedias Well-Known Member

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    Sounds like a bad connector or faulty endstop or cable. Unlikely to be firmware.

    Swap the endstop and see if the problem follows it or persists.
     
  3. Alex9779

    Alex9779 Moderator
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    Yes I had this a few times. Usually not when normally homing but in the homing done after a bed leveling...
    I didn't track it don't because it was not reproducible.
    I also thought about a firmware bug but a electrical issue was also possible.
    Though I have to say that since I am using RC7 I didn't see that issue anymore...
     
  4. pSimon

    pSimon Member

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    I've seen this too, though not often.

    I'd suspect its pickup on the microswitch inputs.

    The pullup seems to be on-chip, and in the "20k-50k" range if the Arduno specs are to be believed, which feels a bit on the high side (esp if at the 50k end of the range), given the length of the wires, and proximity to stepper wiring. (Then there's RFI too).
     
  5. Dr Jeep

    Dr Jeep Well-Known Member

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    yes but....it's a pull up with a NC switch contact on the endstop. So when the endstop isn't active one end of that cable is grounded and it should then take a significant spike to get the other end of the cable to the switching point (given the cable lengths here). Because it's NC if the wiring has an open circuit then that causes the opposite problem and you'd be at home all the time.

    So overall a bit confused as to why you'd see this unless there was an intermittent short on the microswitch wiring.
     
  6. pSimon

    pSimon Member

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    Ah, assumed the switches were NO rather than NC.
     

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