Duet 2 Maestro, something shorted?



  • Hi All,

    I have a Duet 2 maestro and its all of a sudden not working right. When it boots up, the heaters are automatically on and just keep getting hotter. I'v read through some troubleshooting posts and noticed that my 3.3V green LED isn't working either (both in USB and VIN), tried removing the endstops/probe but that didnt help the 3.3v LED.

    Any ideas what i should try next? thanks in advance. Really hope to get back to printing asap.

    PS I have a promega (m3d support is a joke, so I feel best way to get this resolved is to do it myself)


  • administrators

    It sounds like either the 3.3V regulator is blown or something is shorting 3.3v to ground. Are any of the W5500 chip, the SD card, or the main processor getting hot?



  • Hi, none of those are getting hot.


  • administrators

    I just noticed this bit in your original post:

    When it boots up, the heaters are automatically on and just keep getting hotter.

    That normally means there has been over-voltage on the +5V rail, which has blown the mosfet driver chip. That would also account for the 3.3V regulator having failed.

    Is there any sign of damage to the small square chip labelled U3, not far from the VIN barrier strip ?



  • It looks good to me.0_1561496069613_IMG_20190625_155132.jpg


  • administrators

    It's hard to know what has failed and why; but my guess is that the 74HCT02 mosfet driver chip has failed (which is why the heaters are turning on) and also the 3.3V regulator. After that, there may or may not be components powered from 3.3V that are also blown.



  • So the solution is a new board? Would this happen with duet 2 vs duet maestro?


  • administrators

    If it were my board and out of warranty, I would remove the 3.3V regulator, feed 3.3V to it through the Z probe connector, and try to communicate with it through USB. If that didn't work I would use the Erase jumper to see if the Bossa port appears, and upload the firmware if it did. If I was able to get fit working like that over USB and Ethernet, then I would replace the 3.3V regulator and the 2 chips that are powered from 5V.


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