Stepper driver dead (caused by multimeter ?)

  • Hi,

    i have/had a brand new Duet Wifi and managed to kill the D4 stepper driver.

    I was connecting the steppers to the crimp connectors and to the Duet wifi and when testing, i forgot that one of the 4 cables to the stepper was still connected to a multimeter. The multimeter was operating in "beep" mode, that means if the probes of the multimeter touch each other (or there are connected) it makes "beep".
    One probe was connected to one of the 4 stepper cables and the other was connected to air - so no connection to what ever.

    Anyhow, this was the only cause i could find why D4 stopped working, M122 D4 shows now a temperature shut down due to overheating/short to ground.
    The D4 TMC stepper driver has now a very small surface hole/mark, about 0.5 mm in diameter (which the others don´t have, i think it wasn´t there before) - i guess this was created when D4 died.

    I have a Duex5, so i can live with one driver less, but the D4 is going ******* hot….. even with no stepper connected.

    So i have some questions:

    1. Can this driver failure really be caused by the multimeter - or do i have another problem? BTW Duet Wifi was working for about 2 weeks and i was finishing the cabling to its final state - so it worked before.

    2. Because D4 is ******* hot now, can i just desolder the TMC2660?

    3. Which TMC2660 do i have to order as a replacement - are there any special issues?

    Thanks in advance!

  • administrators

    If you are certain that the other multimeter probe couldn't have touched anything, then ask your supplier for a warranty replacement.

    Otherwise, if you are in the US then PM forum user W3DRK, he operates a repair service and can replace the driver chip for you.

    If you decide to replace it yourself, then you will need a hotplate to preheat the Duet, and hot air rework equipment. You need to protect the white Molex connectors from the hot air. Or you can usually pull the plastic parts off with pliers, then put them back when you have replaced the driver chip.

    AFAIK the TMC2660 is only available in a single variant. The distributor is Digikey.

  • Thanks dc42.

    D4 gets increadibly hot now, that is the reason why i want to get rid of it. Maybe it desolders itself if i wait.

    In principle i am used to soldering and a hot air gun is no problem - but why do i need a hot plate - is there a special reason ?

    I have time and no hot plate;) I would just desolder pin by pin…. the TMC is already dead and i can cut the pins.... if necessary.

    I can not be totally sure about the probe not touching anything, but at least at the time when i checked it it was not. If the probe was shortening it to ground, could this be the reason ?

    BTW until this mistake i had a lot of fun with the Duet! Good job!

  • administrators

    The PCB acts as a heatsink for the TMC2660, so it's easier to desolder it if you heat the PCB to about 120C and then use the hot air.

    If the multimeter was on the continuity test setting then I think it's unlikely that a short to the other probe would cause the driver to fail. Does the multimeter still work on that setting?

  • I cannot find any malfunction of the multimeter so far.

    I also don´t understand how this could happen. According to other threads, the TMC in combination with the Duet Wifi is quite dummy proof and a short should not harm too much.

    The multimeter was the only mistake i could find. For 2 weeks before it worked with the "preliminarily" cabling without problems.
    The probe was lying not far away from the steel frame of the printer. The steel frame is yet not grounded. Could it be that an "inductive" spark between the steel frame and the probe did it ?

    Thanks for your explanations and hints. I will start to desolder the TMC the old way, without a heat gun, because removing the plastic parts and so on takes longer….

  • administrators

    A short across a stepper motor coil or between an output and ground may or may not damage a TMC driver. But I don't think the multimeter was to blame. I suggest you ask your supplier for a warranty replacement or repair instead of trying to remove the driver yourself.

  • Thanks again dc42. Which supplier should i ask ?

    I desoldered it already.

    For all who wants to see a dead TMC, there is an image below. The right TMC has a tiny hole - this is the sign of ultimate death!

  • administrators

    If you've desoldered it already then a warranty replacement is no longer an option. However, if you didn't damage the PCB traces in the process, then you should find it easy enough to solder a new driver in.

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