Semitec 104GT thermistor odd behavior



  • Hardware issue: Semitec 104GT thermistor
    Board: Duet2 Maestro

    Was hoping I could be pointed int the right direction. I noticed my long test print had failed and checked the log. Seems the thermister ran a fault failing to rise to temp in time 3 hours in. I ran another calibration and saved with M500. Babysitting it I found some curious behavior (see attached pic)0_1552157299162_tempswing.png

    I did some digging around here in the fourms and found numerous old posts citing issues from PT100 in terms of interferrence from steppers and such. I don't believe that's whats happening here but I thought it worth asking about. The other more obvious cause could be from bad connection. So I checked this and I show to have continuity on both legs while the gantry is in motion. Also the giggle test. Perhaps there is something else woth testing or another method I could try?

    Thank you for your help.


  • administrators

    With thermistors, positive temperature jumps are typically caused by short circuits between the thermistor wires, or between a thermistor wire and the hot end metalwork. Negative going jumps are caused by bad connections, or by a short between a thermistor wire and the hot end metalwork, or a failing thermistor.



  • @dc42
    Very good info to know thank you. Ill trace the entire wire and double check all connections to be sure. Based on your information and the image i'm assuming a bad connection that I haven't found yet.

    Thank you



  • I was just having the same type of issues after switching to a Semitec and my graphs looked just like yours.I checked the wiring and couldn't find any problems.The extruder movement was causing an issue with the connection on the thermistor.I crimped new terminals on the thermistor and made sure they were crimped correctly and the problem was corrected.



  • @siblues Just resolved the issue. Same as yours actually. Found the dupont connector I had used to the board was not seating properly. Used a new one and is working properly. Never thought to giggle test the board connections since in my mind it wasnt a moving part. As the printer vibrated just right it giggle the connector causing the fault.

    On to printing!



  • Glad to hear you sorted it out.



  • @gencab said in Semitec 104GT thermistor odd behavior:

    giggle test

    I'm sure something is lost in translation here. Giggle as in laugh? Or does it mean wiggle, as in move around?



  • @phaedrux said in Semitec 104GT thermistor odd behavior:

    I'm sure something is lost in translation here. Giggle as in laugh? Or does it mean wiggle, as in move around?

    Dunno - do a Giggle search and see what comes up ☺



  • @phaedrux best typo ever. Giggle meant to be jiggle but my brain took the wheel on that one. I can always try the giggle test. 🙂

    Giggle test: stare at your printer with intent. Proceed to giggle at it. Record your results. If your printer giggle back call the local law enforcement. or the SCP foundation and let them know SCP-1146 got away.


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