Burned Z axis pin on board.



  • As the title says, a pin on my z motor connector on the board burned a bit today and let some delish smoke out right by my face.
    The board has been working. Just after i jogged the z axis up the motor powered off. Kinda hard not to notice 8 inches away. Good thing i have thermal camera for my phone.

    So this is what it looks like warmed up doing some print moves for 8 or so hours
    https://photos.app.goo.gl/1mjBFFsXkmjFQDHp2

    This is just less than 3 minutes of being on, as you can see the board is cold except where the z axis drive is, no other drivers were warm yet.
    https://photos.app.goo.gl/BGosGwlOksYik6t43

    and a cooked connector which was welded to the boards pin
    https://photos.app.goo.gl/dLoE5G1RwA5Wqh7H2
    https://photos.app.goo.gl/MlVUNjRYHnxJPjBs2

    So all in all not sure if the board is safe to use anymore.


  • administrators

    With the Z motor disconnected, does the Z driver chip get hot?



  • The motor was always plugged in, the thermal image shows its much warmer than the cold board that was maybe on for a few minutes max.


  • administrators

    I suspect one of the following:

    1. A bad crimp connection to the pin that got burned. This would account for why only one pin shows signs of overheating. It may also have led to failure of the Z driver.

    2. A short in either the motor or the wiring to it, either between the phases, or a short to ground from the wire that of burned. A short to ground would explain why only one of the pins burned.

    3. It's possible that root cause was a faulty Z driver; but that doesn't explain why only one of the pins burned.



  • I don't see an issue with the crimped wire shown in the picture, but you can see there is some burning from a arc. The driver does'nt have a blow hole like the others did.

    I'm still in the testing and setup phase on the printer so that could be it, but its been working for a few weeks with no problem.
    I'll have a look at the wires from the board to the motor, The motor is a nema23 running on 1050Ma any lower it loses steps.

    Would a thermal video of the board powering on help? ill try to get the motor wires and board in the shot


  • administrators

    I don't think a thermal video would help. I think the most important things for you to do now are:

    1. Check for a short to ground or to the stepper motor casing from the wire that got burned.

    2. Check whether the Z driver gets hot, when Z movement is commanded but no Z motor is connected. If so then the Z driver has failed. Assuming you are running either current stable firmware (1.19.2) or a 1.20 beta, you should also get error messages if the driver is overheating or has a shorted mosfet



  • Which M code gets the error codes again?


  • administrators

    M122 produces a diagnostic report. However, if you are running firmware 1.19.2 or later, you don't need to run M122 because error messages will be generated if overheating or a short to ground is detected.



  • alright sounds good im running 1.20Beta11 so it should be good


  • administrators

    So if the Z driver remains cool when you command Z movement (to enable the driver and set the current) with no Z motor connected, then the driver chip may still be OK. Check the Z motor and wiring for shorts, re-make that connection, and try again.



  • Everything thing checks out, no grounding of any coils, the driver stays cool.
    No shorts found I had a electrical engineer look over it he came up the same thing.

    Thermal made it obvious that it's not warming up at all.

    So I'll re-pin the wires and test some more



  • Ok after all that. It turns out the driver doesn't drive the Z properly skips steps and has no tourqe . Swapping in the x axis driver it works great at a lower current.
    Also hooked up a scope she's a noisy one.



  • I dont think the fault was my doing, but ive been wrong before. So what to do?



  • David what can we do about this?


  • administrators

    If your Duet is still under warranty, email your supplier.



  • It's probably not as this will be the second time a driver has failed and the third board to shit it self.

    Overall this is giving me a bad taste, what are my options if my warranty is over? I haven't even done a single print with the thing.



  • I received my replacement in September so does that mean its under warranty ?


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