Duet 2 Maestro dead - power LED flashes, then nothing.

dooloo12

I've upgraded my Ender 3 Pro to use the Duet 2 Maestro board (which I love, btw), and everything has been chugging along fine, I've printed roughly a Kg of PETG, and was switching to PLA. I switched off the power, leveled the bed by hand, switched power back on, loaded some bed level checking gcode, and walked away while the bed was heating. I came back to find the web interface telling me it's lost contact with the board, and no lights on the board.

Things I've checked so far: Power supply is fine, outputs 24 volts as expected. I haven't tried it under load, so maybe there's something that only shows up when drawing current, but that seems unlikely. Power supply fuse is good. Turning on the power makes the Vin LED flash briefly, but that's all. It seems to have died completely. The only thing I can think of is that in moving the hot end around by hand during the leveling process I generated power through the steppers that fried the board, but I've done this at least 20 times, and it was OK at first when I turned it back on - only after I started the process of heating the bed did it die.

I have a good multimeter but before I go poking around I wanted to see if there's anyone whose run into this or any suggestions about what might be going on and how to fix it. I really like the board so far, so I'd very much like to revive it.

dc42

@dooloo12 said in Duet 2 Maestro dead - power LED flashes, then nothing.:

Turning on the power makes the Vin LED flash briefly, but that's all.

Most likely your PSU is cutting out when the Duet starts up, or you have a bad connection between the PSU and the Duet. So measure the voltage at the PSU output terminals with the Duet connected, after the VIN LED has flashed and gone out. If it's still 24V then measure the voltage at the Duet VIN terminals.

dooloo12

@dc42

Bingo! 2.7 volts out from PSU when connected to the board. Thanks! I'll replace the
PSU ASAP.

dc42

@dooloo12 it may be the PSU that is faulty, but the other possibility is that a component on the Duet (e.g. a stepper driver) has failed and is drawing a lot of current, causing the PSU to go into short-circuit protection mode.

You might want to try connecting the bed heater (and not the Duet) to the PSU, to test whether the PSU can still power the bed heater.

dooloo12

@dc42
Seems like this is it. I have another supply, 24 V, 14.6 Amps, so I hooked that up. Same result, except the power supply keeps resetting so the LED flashes every few seconds.

I tried unplugging all steppers, same result. I fear I may have fried something important.

dc42

@dooloo12 said in Duet 2 Maestro dead - power LED flashes, then nothing.:

@dc42
Seems like this is it. I have another supply, 24 V, 14.6 Amps, so I hooked that up. Same result, except the power supply keeps resetting so the LED flashes every few seconds.

I tried unplugging all steppers, same result. I fear I may have fried something important.

Assuming that the underside of board isn't touching something conductive that is shorting the pins out, and you have disconnected everything except power, then I think most likely that either one of the stepper drivers or the A4403 voltage regulator has failed short circuit. When using that second PSU, you may find that the failed component is getting warm. Also check that none of the electrolytic capacitors has exploded.