Short circuit error on Kossel XL with duet wifi



  • @T3P3Tony:

    Can you describe how the thermistor values are jumping about. What values do you get and do they change when everything is still or only when you move/touch the hotend/bed

    0 Ohms on the heated bed indicates a short circuit. I would expect about 1Ohm for a "standard" heatbeds on a 12V system

    I'll have to record all of the readings i get from the thermistor but i made sure to be steady and accurate with it. If this heat bed is indeed shorted, what would the next step be? Replacement? Thanks for your help so far.


  • administrators

    One more question, are you taking the measurements with the heatbed/ thermistors unplugged from the Duet board? If not you need to.



  • Thermistor values on the hot end jump around from .338, .466, 1.326, and about 10 other numbers. The measurements of resistance were taken from the heat bed while it was completely removed from the printer.



  • The interesting part is that even though the heat bed has a short it heats up just fine, it's the hot end that doesn't heat up. What else can i check for to diagnose the hot end issue?


  • administrators

    Those thermistor values are so low - looks like the multimeter just picking up noise. You are looking for values in the region of 100K for a 100K thermistor.

    Do you get the same readings of for the extruder and bed thermistors?

    If not then what temperature for the bed is displayed when the bed thermistor is plugged in?



  • @T3P3Tony:

    Those thermistor values are so low - looks like the multimeter just picking up noise. You are looking for values in the region of 100K for a 100K thermistor.

    Do you get the same readings of for the extruder and bed thermistors?

    If not then what temperature for the bed is displayed when the bed thermistor is plugged in?

    I'm not sure how to test the extruder thermistor, there's only a white connector with 4 different color wires coming out of my extruder. ( E3D Titan ).

    When my bed is plugged in and reading from the duet wifi control, the temperature is 34 Degrees Celsius.

    Thinking maybe my hotend board might be burnt out?



  • There is no extruder thermistor. There is the hotend thermistor.
    The 4 color wires from Titan are the motor wires. You need to measure the two wires (either white or red/black) coming from down below, inside the heater block where the nozzle is.



  • @sigxcpu:

    There is no extruder thermistor. There is the hotend thermistor.
    The 4 color wires from Titan are the motor wires. You need to measure the two wires (either white or red/black) coming from down below, inside the heater block where the nozzle is.

    Gotchya, measuring those 2 wires from my hot end i got a range of numbers. I listed a few of the ones in an above post.


  • administrators

    So just to be clear you should have 2 thin wires and two thick wires coming from your hotend. Then another 4 wires (probably black blue green red) coming from the e3d titan motor. Ignore the 4 wires coming from the titan motor. Check the resistance across the two thin thermistor wires where they plug into the board, but with them not plugged into the board. If you get similar readings to those you already mentioned then you have a short circuit on your thermistor



  • @T3P3Tony:

    So just to be clear you should have 2 thin wires and two thick wires coming from your hotend. Then another 4 wires (probably black blue green red) coming from the e3d titan motor. Ignore the 4 wires coming from the titan motor. Check the resistance across the two thin thermistor wires where they plug into the board, but with them not plugged into the board. If you get similar readings to those you already mentioned then you have a short circuit on your thermistor

    Ok so the 2 thick wires are what i originally tested and what gave me the numbers that jump around.

    The 2 thin wires i'm not able to test because of the connector they go to, i tried sticking my multimeter sticks in the 2 holes but didn't get a reading. Should i cut the wires off from the connector to get a reading from the bare wires?

    I've attached a picture just to show what i'm talking about.

    https://postimg.org/image/dqe59walv/


  • administrators

    You could put wires in the connector holes and measure between those.



  • @dc42:

    You could put wires in the connector holes and measure between those.

    I put wires into the holes as far back as i could and measured but still get a reading of .0L. Perhaps i'm measuring it incorrectly? I used speaker wire and made sure to stick them in as far as they would go.



  • I ended up stripping the wires just to be sure. Still same error message.


  • administrators

    Sounds like you have a faulty thermistor or faulty wires between the board and the thermistor on your hotend.



  • @T3P3Tony:

    Sounds like you have a faulty thermistor or faulty wires between the board and the thermistor on your hotend.

    Ok I'll look into replacing the thermistor. Is it possible I blew that little board that sits above the hotend? The one i plug everything into.


  • administrators

    Ahh hold on. I did not realise you had a hotend PCB. That is another point where there could be an error. So measure the resistance of the the thermistor at the plug that plugs the thermistor into the hotend PCB. Also measure the reisitance of the connection from the hotend PCB back to the plug onto the Duet. The thermistor should be 100K ( the wires should be almost 0 Ohms.



  • So i measured the pictured black and green wires and got a resistance of .010 when the mm is set to 2M. Hope that's normal.

    https://postimg.org/image/qfql2u489/

    I measured the resistance of the thermistor plug (link to picture in a previous post) and got the same .0l reading.

    Thanks for all of your help so far everyone. I'm a total noob. lol



  • Does anyone know where i can find the hotend pcb? I tried looking on the E3D website and the Think3dprint3d website but did not see it.

    Was also wondering this…since my hotend pcb still powers on my 2 fans connected to it...is it safe to assume that it's ok? I'm now thinking it's just the thermistor that needs to be replaced..


  • administrators

    The Hotend PCB is on Github here:

    https://github.com/T3P3/KosselHotendBoard

    It certainly sounds like a new thermistor is the most likely.



  • @T3P3Tony:

    The Hotend PCB is on Github here:

    https://github.com/T3P3/KosselHotendBoard

    It certainly sounds like a new thermistor is the most likely.

    Awesome, I'll start there. Should i replace both wires coming out of my hotend? or just the thicker red one?


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