Short-to-ground problem



  • Hello,

    I have Duet 2 ethernet and DuetX2.
    I had connected X and Y stepper motors and 3 Z stepper motors and everything worked perfect.
    I tried today to connect the extruder motor a 17HS10-0704S pancake model. As I had not connected yet the extruder I could not tested the motion because of low nozzle temp warning by Duet.
    So I disconnected the X axis and connected the extruder motor to x driver. When I tried to move the extruder motor a buzzing sound started and the motor started to get very hot. I tried to switch of the duet asap but smoke get out from the stepper driver.
    I re connected the X stepper motor but I got an Error: short-to-ground reported by driver(s) 0 and zero move from the motor.
    I reassigned X0 axis to E1 driver and now I can move correctly X,Y and Z axis.
    I do not know now if the extruder stepper motor works and if I have to connect it to Duet E0 and what caused the problem. I do not want to burn another stepper driver again. Shall I buy a new one ? It was a cable connection issue ?



  • To cover the basics; you powered off the board before connecting / disconnecting?


  • Moderator

    @gbiski said in Short-to-ground problem:

    17HS10-0704S

    These steppers are small, and need a low current to run. From these specs https://www.omc-stepperonline.com/nema-17-bipolar-1-8deg-13ncm-18-4oz-in-0-7a-2-9v-42x42x25mm-4-wires.html motor current max is 0.7A, so should be set to maximum 80%, or 560milliAmps. If you didn't reduce the current from the existing stepper motor (post your config.g, it will show what it is set to), most likely too much current has been put through the motor, heated it up, melted the internal coil winding, shorted the motor, then caused the stepper driver to fail.

    It's also possible if the phases were incorrectly connected that that made the process happen even faster.

    The only way to test the stepper motor is to check the resistance of the phases with a multimeter, and check the two phases aren't shorting between them. The phase resistance should be 4.2ohms. Test each wire with one other; only two pairs should show this resistance. If there are shorts across the two phases, throw the motor away and put it down to experience.

    There are some people in the community who may be able to repair your Duet for you, depending on where you are. See https://forum.duet3d.com/topic/13875/community-repairs

    Ian



  • @bearer yes always do this



  • @droftarts Thanks a lot for your reply.
    Hereby my config:
    M906 X1300 Y1300 Z1300 E1000 I30 ; set motor currents (mA) and motor idle factor in per cent
    I had an e3d pancake and with similar currents I never had an issue.....
    If I use the E1 for X do you think that will be an issue ?


  • Moderator

    @gbiski said in Short-to-ground problem:

    I had an e3d pancake and with similar currents I never had an issue.....

    All motors are not the same ... https://e3d-online.com/slimline-motor ... it has a max current per phase of 1.4A!

    It should be fine to use E1 for X. If you remap with M584, it will use all the X values you have set, including motor current.

    Ian



  • @droftarts
    So you think that most probably it was not the wiring but the current ?
    Do you think it is correct the following lines having assigned E1 to X (I assigned 600 mA to E0) ?
    M584 X4 Y1 Z2:5:6 E0
    M671 X0:165:330 Y165:330:165 S0.5
    M350 X16 Y16 Z16 E16 I1
    M92 X80.00 Y80.00 Z400.00 E830.00
    M906 X1150 Y1150 Z1150 E600:1150 I30
    M84 S30


  • Moderator

    @gbiski said in Short-to-ground problem:

    So you think that most probably it was not the wiring but the current ?

    It could have been BOTH. You need to check the motor before connecting it again, as I said above, or you may destroy another stepper driver. My guess is that it has short circuited internally and failed.

    Do you think it is correct the following lines having assigned E1 to X (I assigned 600 mA to E0) ?
    M584 X4 Y1 Z2:5:6 E0
    M671 X0:165:330 Y165:330:165 S0.5
    M350 X16 Y16 Z16 E16 I1
    M92 X80.00 Y80.00 Z400.00 E830.00
    M906 X1150 Y1150 Z1150 E600:1150 I30
    M84 S30

    You can specify them in any order in M584, so long as the physical motors are connected in the same order. The other motor settings will be applied to the stepper driver as defined. So yes, looks okay, except:

    M906 X1150 Y1150 Z1150 E600:1150 I30

    Remove one of the E numbers, you only need one, eg M906 X1150 Y1150 Z1150 E600 I30. But you'll need to set the current correctly for whatever stepper motor you connect.

    Ian


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