No Green LED, I have disconnected everything on the board

  • when I plug in the the USB i get 2 red lights and no green.
    what next?

  • administrators

    Is any of the chips or the WiFi module getting hot?

  • It is an ethernet board, but not that I have noticed. Are there any points you want me to hand feel. Basically, we have hardly had the board on.

  • administrators

    Some possibilities:

    1. You may have connected endstop switches to the wrong pins on an endstop connectors, so that they are shorting out the 3.3V rail. Remove all power (including USB), disconnect the endstop switches from the Duet, then reapply power and see if the green LED lights up.

    2. It could be just the green LED that has failed (or is badly soldered to the PCB). If you have a multimeter, please check whether you have 3.3V between the 3V3 and GND pins of any endstop connector, with no endstop switches connected.

  • I had already removed ALL connections of any kind, including the end stops, it is a bare board with only the thermocouple board installed. When I plug in the USB, i get no green light.

    We also already checked voltage on the end stop, no voltage - .6 only. Panel Due pins 4.7v.

    It seems that 24v is some how getting onto the 3.3 and the 5v. It blew out one of the USB ports on my computer. I suspect because it sent 24 v. But how would this be possible? What can we test?

    All wires are insulated and terminated in a plastic connector of some kind. The board is mounted on nylon spacers. The plastic washers were used on the top of the board. We confirmed that the output voltage was below 25v prior to powering on. The frame and most of the motors are grounded to a commercial ground bus bar. One motor is grounded to the ground wire of the 24v fan wire ground.

  • administrators

    Can you tell us a little about how you wired the Duet to other components in your printer? In particular:

    • What sort of endstop switches did you connect?
    • What sort of Z probe did you connect?
    • Did you connect anything to the expansion connector?

  • "One motor is grounded to the ground wire of the 24v fan wire ground."

    This could be the problem.

    With the fan off, that "ground" you've made will see 24v, since the FETs on the board are low side fets (they switch on the negative side).

    So you created a path for 24v to get to the motor, presumably the chassis, and from there it likely found a path into a lower voltage bus.

  • IR probe for Z, mechanical end stops for x & y. Heater is via SSR.
    Only expansion board is thermocouple, which had 2 type k thermocouples attached.

    We checked the IR probe in detail, it is not touching the hot end and is mounted in a plastic

  • administrators

    Please check whether the main processor (the big square chip) or U2 or U11 is getting hot when power is applied.

  • No extra heat

  • administrators

    Thanks. I understand that arrangements have been made to replace your Duet under warranty.

  • Yes, we have received the new board and all the LED's are now working. Thank you.

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