Motor Capacitor - Wrong Polarity ?



  • I've just received my Duet Wifi today and noticed that the X axis stepper driver's capacitor looks to be the wrong way around, according to the silkscreen and the capacitors for the other drivers. Please see picture:

    Also it's really nice to see a full set of connectors along with loads of spare crimps and the ferrules, as well as the included SD card. I noticed that the ferrules do not follow the standard colour code based on their size, but they seem to be as the black ferrules which are usually for 1.5mm^2 cable. The heat bed / power input connectors allow grey (2.5mm^2) ferrules to fit which are ideal for 14awg cable so it might be nice to include that size, given the currents involved. The smaller white ferrules are too long for the extruder heater connectors and need to be cut down. Also it would be nice if the screw-terminal connectors were the detachable type, if they can be sourced with the correct ratings - Although I've just used XT60 connectors / 14AWG pigtails on mine.

    It looks like the silkscreen for the X, Y and Z axis motors say "* Stop" rather than "* Step" - Although the text is rather small so it might just be the font.

    Finally, it would be nice if there was a little more space around the optional step / direction headers so that Molex KK connectors can be used.



  • Just looked at a Duet Wifi I have on hand, and it does seem like that cap is backwards. Which is odd as I'd have expected it to fail during testing. Tony?

    The silkscreen does say 'stop', as it is the endstop for that motor.


  • administrators

    I agree, the capacitor is the wrong way round. Ask your supplier for a replacement board, and don't apply VIN power to the board.

    The 'stop' legends refer to the LEDs they are next to.



  • Thank you both for confirming. I also would have expected it to fail (dramatically) during testing, it's a good thing I only powered it via the USB port when I got it.

    I would usually just fix it myself, but I'm not sure if the capacitor would have been damaged during whatever testing that was done during manufacturing.

    The silkscreen makes much more sense now, I didn't even notice the LEDs.


  • administrators

    Hi Andrew, I have emailed you.


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