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Runaway Hotend

Discussion in 'Troubleshooting' started by ColoradoBob, Nov 8, 2017.

  1. ColoradoBob

    ColoradoBob New Member

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    Hello Everyone,

    I have some weird behavior I'm hoping someone has encountered and has a solution for.

    I recently had to replace the RAMPS board (ordered the full Arduino and RAMPS from Robo). Once I got the new board in and installed everything seemed to work fine with one exception.

    Now if I heat the Hotend on its own (to install filament, etc.), the temperature is regulated well and stops heating at the temperature I set.

    However, once I heat the Bed, the Hotend kicks on as well (without me asking it to) and does not stop until I get a temperature fault. It's heating to well over 245C until I get a temp error (I use Octoprint) and it turns off).

    Has anyone encountered this?

    Thanks a ton in advance for the help!
     
    #1 ColoradoBob, Nov 8, 2017
  2. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    I have never seen such behavior, if you just heat the bed in the OctoPrint interface does it also kick on the hotend?
     
    #2 WheresWaldo, Nov 9, 2017
  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Worst case this could be faulty electronics still.
    However that is an odd one.
     
    #3 mark tomlinson, Nov 9, 2017
  4. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Could it be thermistor related?
     
    #4 WheresWaldo, Nov 9, 2017
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Unless that is a false reading (I'd think that is unlikely given the description) I am not leaning towards a thermistor issue -- they appear to be reading correctly.

    If software really is controlling this (heating the hotend after the bed) it is still a problem since the hotend heating is uncontrolled.
    If it is NOT being done by the control software (in other words, if the software is only commanding bed heat) then it is hardware in some way... really odd. If it were mine I'd replace the Arduino as well just for a test, but not everyone keeps a pile of spare parts :)
     
    #5 mark tomlinson, Nov 9, 2017
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Worth noting again that when I bought the standalone RAMPS 1.4 cards from Amazon (ones that were just the RAMPS and not part of the complete kits) I went through three cards from three vendors to get one that worked. Those were the really cheap ones and I wrote it off as you get what you pay for. That was much earlier in the year (and because I ordered them Prime they handled the refund well).

    Not saying this is absolutely a bad RAMPS (mine were definitely card issues because they would drive the Arduino into overload and cause the CPU to overheat when installed) but just pointing this out.

    I am not certain how a faulty RAMPS would do this since it is two completely different I/O channels (and MOSFETs) one for the bed and one for the extruder, but I don't think we can rule it out.
     
    #6 mark tomlinson, Nov 9, 2017
  7. Geof

    Geof Volunteer Moderator
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    Every time I've heard of both heating at once it has been a faulty ramps. I suggest contacting robo to replace your electronics combo as yours is likely defective.
     
    #7 Geof, Nov 9, 2017
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  8. ColoradoBob

    ColoradoBob New Member

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    I agree that it is very strange. I connected Simplify3D Directly to the Printer and took a screen recording of the behavior that also shows the GCode being sent.

    The code looks okay to me, but the Hotend is heating with the Heated Bed.

    Thoughts?

     
    #8 ColoradoBob, Nov 9, 2017
  9. Geof

    Geof Volunteer Moderator
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    still think the ramps or arduino is toast
     
    #9 Geof, Nov 9, 2017
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  10. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The software does not even have the heater for the hotend enabled ... so if it is heating anyway you have a hardware problem.
     
    #10 mark tomlinson, Nov 9, 2017
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  11. ColoradoBob

    ColoradoBob New Member

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    I'm thinking hardware as well, but needed the second opinions. I'll reach out to Robo support and see where it goes.

    Thanks a ton for the thoughts!
     
    #11 ColoradoBob, Nov 9, 2017
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