Driver 5 "bad" phase

  • Hello Forum,

    I currently have a problem with my Duet3 6HC. When controlling the stepper motor on channel 5 the motor runs bad and one phase seems to be not controlled correctly. The driver repots "short to GND". I have swapped the motor to an other channel and tried a second motor on the bad channel. The motors and the wiring seems to be ok.

    I have made several measurements and everything seems to be ok. The PWM is clean at the gate of the FETs and also looks good at the output. The high and low side FETs inside the half bridges seem to be ok, too, since i loaded them with some resitive load against V+ and GND. During the measurement at the shunts i found that there is no current flow in one phase although both shunt resistors are ok. But I don't want to exclude that the contact was not good during the measurement.

    Has anybody ever had a similar problem or has any other ideas where the fault could be? Currently I assume that the Trinamic Chip is defective.

  • Moderator

    @Parceval You may have run into a recent issue; see this thread:

    This fault will generally show itself if you're using 24VIN, but not if you use 12VIN. Can you check with the thread above and see if you may have one of the affected boards?


  • Hello and thank you for the quick response,

    i must have overlooked this thread druing my search. I have tested the board with 12V and it seems to work.

    My board has the serial number WD31722. I can send you the output of the M122 command by e-mail, if needed.

    If i'm right i have an version 1.0 Board with no diodes, is there a possibility to fix this problem?

  • administrators

    Since you obviously know what you are doing, can you check that all eight 47R mosfet gate resistors are in place on that driver, with both ends soldered down?

    We have found the TMC5160 chips to be very reliable. If it works OK on 12V but not on 24V, and your board doesn't have the diodes, then my suspicion is that one of the mosfet gate resistors is not soldered down, or (unlikely but not impossible) has the wrong value.

    If we can't resolve it by here then we'll offer you a warranty replacement, even it if is out-of time.

  • I measured the resistors and they are all 47 Ohm with a maximum tolerance of plus 1%. After re-soldering all gate resistors the output seems to work again. I will do a longer test run to check the reliability. Thanks a lot for the quick help.

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