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Solved error MINTEMP

Discussion in 'Troubleshooting' started by JohnAB, Nov 21, 2021.

  1. JohnAB

    JohnAB New Member

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    Stopped all control. Is this because of a open thermocouple connection or defective thermocouple?
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Yes, it could be either of those (but it is a thermistor -- not a thermocouple).

    The thermistor is NTC (negative temperature coefficient) so as temperature goes DOWN the resistance goes UP. Thus an open circuit (broken wire or connector or thermistor) which is max resistance will read zero dgrees.
     
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  3. JohnAB

    JohnAB New Member

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    Thanks for your help. I have ordered a new thermistor and wire/connector. I also order a back-up heater.
    John
     
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  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Good idea. The heater core could be getting old/weak. They do wear out and when they do they usually just stop altogether, but it is a good idea to try it. I always recommend the higher wattage ones (40w) since they heat faster and maitain better.
     
  5. JohnAB

    JohnAB New Member

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    I got the parts and the thermistor was not the same as the one I have. In the end it was a broken wire to the thermistor.
    I got this Robo 3D printer from a friend used. The wiring to the hot end was very messy, I have fixed it much better now. There it no model/ serial number that I can find so I don't know the exact model.
    How can I tell what type of robo 3d printer I have?
     
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Post a picture somewhere. The entire meachine and then a close-up of where the threaded rod goes under the bed. If you can't post it here use imagur or flickr -- any place you can upload it and post a link.

    Original beta unit and the R1 had glass bead thermistors, the R1+ (and any recent E3D conversions) all have canister style thremmistors (they are mounted in a small can that fits into the heater block rather than the glass bead)
     
  7. JohnAB

    JohnAB New Member

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    IMG_20211125_221049385~2.jpg I am trying to post a picture of the hot end of my printer. The thermistor are two very thin wires rapped with blue hi-temp insulation. The wires go under a 2mm button head Allen head screw. IMG_20211125_221049385~2.jpg IMG_20211125_221049385~2.jpg
     
  8. JohnAB

    JohnAB New Member

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    I am trying to post a picture of the hot end of my printer. The thermistor are two very thin wires rapped with blue hi-temp insulation. The wires go under a 2mm button head Allen head screw. View attachment 18725 View attachment 18725
     
  9. JohnAB

    JohnAB New Member

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    To finish. As you can see the two wires go under the screw like a thermocouple is made sometimes.
    John
     
  10. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Well, the MINTEMP error is from an open-circuit thermistor so you have the wire or a connector broken loose. That style of installation for a thermistor was used in the BETA and R1 printers. They switched to cartridge type thermistors for the R1+ (those have a metal can around them). So the thermistor is a small glass bead that is under that screw (and attached to the end of the wires).
     
  11. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Probably the easiest way to test this is to remove the screw and the thermistor from under it. Make sure the wires are not broken, but the thermistor can be creaked interally ... If you do need a new thermsitor (which is most likely) get one from PartsBuilt or amazon.

    Here is partsbuilt : https://www.partsbuilt.com/ntc3950-glass-thermistor-1meter-ab-cable-dupont/
    Here is a list at Amazon: https://www.amazon.com/s?k=NTC+3950+Thermistor&ref=nb_sb_noss_2

    You can connect the new thermistor and test it before putting it under the screw by just powering on the printer and see what temperature it reads for the hotend. room temperature is usally low-to-mid 20's C
     
  12. JohnAB

    JohnAB New Member

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    Thanks so much for your help.
    John
     

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