Killed my Duet 2 Maestro? Snap/pop & magic pixie dust smell.

tinker

I have the Duet 2 Maestro with the 2 driver expansion board. I took the expansion board off to measure it and when I put it back I may have misaligned by one pin. The motor connectors were definitely correct as I labeled them. Turn on the printer and immediately heard a snap/pop and smelt the magic pixie dust. Turned it off within a second and pulled the expansion board off which was already hot by X1 driver chip.

The main board no longer boots with the expansion board removed.

Can't see any visible damage to components under a magnifier.
I smell burnt electronics by the microSD card slot.
Only the Vin LED Blue and V5 LED Red are lit. Ethernet LEDs do not light.
Cannot access web control.
PanelDue screen shows basic icons but no info and nothing works.
BLtouch probe does cycle.

Can anyone suggest where I should start trying to fix the board. Any fuses?
Have multimeter and basic pocket oscilloscope.

Thanks for any help.

Phaedrux

You can start with this guide

https://docs.duet3d.com/en/User_manual/Troubleshooting/Duet_wont_respond

But it definitely doesn't sound good. You can disconnect everything and take some good photos of the board and maybe we can spot something that got damaged.

Try and note any other chips that get hot.

tinker

@phaedrux Disconnected everything except USB and got:

USB LED always on
5v LED always on
3.3v LED always off
Diag LED: With USB disconnected for > 30 sec then connected it stays on. If USB removed for 5 sec and then connected the LED never comes on.

U2 very hot. (regulator?) 5v in, 0.35v out. Guessing this is part of the problem.

Did not run any more tests since U2 was very hot after 10 seconds.

Any indications its possible or not to save?

Here's a pic of the board. Forum would not let me post a bigger one. Let me know if you want more zoomed in pics.

dc42

@tinker is either U10 or the main processor also warm?

tinker

@dc42 Yes main processor is uncomfortable hot to the touch. I'm guessing that's bad. U10 is cool.

dc42

@tinker it sounds to me that the main processor has failed, probably due to over voltage, and is drawing excessive current from the 3.3V rail.

tinker

Thank you all for the help and sorry for late reply. Ended up getting replacement boards (main and expansion) at a very good price and thankfully nothing blew up when I reconnected. I had all connections labeled with orientation, and double checked, but was still weary when flicking the power switch on!

Really kicking myself for working on it late at night, in low light levels, leading to the 1 pin misalignment mishap. Constantly live and learn!