Thermistor Reading Wrong Temp

Discussion in 'E3D-v6 and Lite6' started by Ryan O'Neill, Mar 5, 2016.

  1. Ryan O'Neill

    Ryan O'Neill Member

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    I just installed the E3D V6 on a new Ultimaker 2 clone I am building. It's the 24V 1.75 universal model. I setup the included thermistor in the marlin firmware like the instructions detail (#define TEMP_SENSOR_0 5) and fire it up for the first time. When I connect the room temp is reading at 7 degrees. It's not that cold in here. So I tell it to heat to 200 degrees. It takes almost a minute before reading anything more than 7, but it does begin climbing steadily, though very slowly. When it reaches 200 I try to feed PLA through, it smokes and spits like an angry cat. It is obviously much hotter than 200. I have checked that the thermistor is seated correctly and reseated it with the same result. What have I done wrong? Any troubleshooting ideas? 2016-03-05 00.31.39.small.jpg
     
  2. Ryan O'Neill

    Ryan O'Neill Member

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    Oh, one bit of info I forgot. The thermistor reads a resistance of 109.2.
     
  3. Mike Kelly

    Mike Kelly Volunteer

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    Take it out and measure the resistance. It may be shorting against the heater block but that doesn't make sense for a resistance of 108ohms. That's like PT100 range
     
  4. Ryan O'Neill

    Ryan O'Neill Member

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    Just pulled it out of the heater block. It's reading a resistance of 103.9. Then put it back in, 100.3.
     
  5. elmoret

    elmoret Administrator

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    Thats a normal thermistor not a PT100 based on the photo. He's probably leaving off the kilo in his measurement.

    What electronics board are you using for your clone? Are you certain that the balancing resistor is a 4.7kohm? A balancing resistor of say, 1k would cause what you're seeing.
     
  6. Ryan O'Neill

    Ryan O'Neill Member

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    It's one of the Ultimaker copies from China. This one to be specific. I am not certain about the resistor at all.
     
  7. elmoret

    elmoret Administrator

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  8. Ryan O'Neill

    Ryan O'Neill Member

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    It's plugged into "Temp 1". Did I make a mistake by assuming it would just work with the new sensor?
     
  9. Ryan O'Neill

    Ryan O'Neill Member

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    Ah yes. Now that I know the words to Google I am seeing that an Ultimaker 2 requires a PT100 sensor. Some detail always gets missed when putting the parts together for a new project. Thanks guys for all the help!
     

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