E3D heater burn spot

  • For my new setup i take two e3d 12v 30w heaters from the last e3d lite y bougth. Both runs for at least 20hs and then the duet trow a thermal warnig, the classic "temp raise too low...". Take off, examine and see a burn spot in each heater insulation.

    Heater 1
    alt text

    Heater 2
    alt text

    E3D suggested that maybe i was not using the original thermistors 😑
    What do you think? i am looking for a chinese heater to use, never have trouble with the 0.6 cents cartridges

  • Are you powering them with 12v or 24v?

  • If the cables are not protected against movement it can render a "hinge" that can cause this too.

  • administrators

    @cata yeah as @brunofporto says it could be a point where the wires are flexing.

  • No flex point in near the burn spots, the burn spots are not in the same length of the cable. The cable is fixed for 10cm or more over the spots

    Are feeding with 12v, no problem with other 2 heaters (absurdly cheap ones)

  • In the unlikely scenario you have been getting defective heater cartridges I am sure E3D would take that very seriously and would want to know about that. Understandably they would probably have you go through a troubleshooting process first before they get to that conclusion.

    Here are some ideas.

    1. strip the heat shrink, and insulation near the burn spot. Then visually inspect for defective crimp, or broken strands in that area.

    2. Strip some fresh wire near the cartridge so the burnt wiring doesn't affect the reading. Then measure the resistance across the heater with an ohm meter to rule out bad cartridge. E3d publishes resistance specs for their heaters. The reading could be bad from damage from overheating so this might not be a conclusive indication of the cause.

    3. Check the installation of your thermistor to verify that its not shorting, intermittently failing open circuit, or decoupled from the heater block.

    4. Check that the 12v supply voltage is actually in the 12-14V range. Note that if you are using a 12V 40 watt cartridge this becomes 54 Watts at 14v!

    If you have everything secured with double strain relief, and its not catching on anything at any point in travel you should be ok. Be careful while installing stuff, wiring the printer, moving axis's around before you have the wiring secured. I have broken wires to thermistors before doing this.

    Thermistors also have different characteristics. We need to tell the firmware which one we are using, so when it reads the voltage it can translate this to the correct temperature.

    I think what they were suggesting since E3D supplied thermistors have a different value than the Generic 100k NTC that are commonly found is to make sure that

    1. you have the correct values set in firmware for the E3D Supplied thermistor.

    2. If you are using a different thermistor, that you have the correct values set for that which will almost certainly be different than the one E3D supplies.

  • Another alternative is that that part of the cables were crimped by accident during manufacturing - sometimes when I am cutting cables I got another part of it crimped from the wrong positioning of the wire cutter.

  • Ok, the fault is on the duet side maybe. I have the same problem now with a heater that have in use 1 year. I see an unnespected raise of 15 degres before the fault. I think that causes the burned spots in the thin point of the e3d cartridges. After the failure the duet becomes too lazy to respond if not reset first, 5 seconds or more to take a gcode command. Cant use the M562 command or reheat the hotend, and the m122 command never be read. Time to erase and reflash to try again