Duet 2 Maestro repair - Blown 3v

[micle546]

Was swapping out the extruder head for another, namely the Ender 3 Sprite head, and somehow blew the (i think) 3v line on the board. I've ID'd a few components on the board that need replaced, and have the new parts in my digikey cart, but am not sure what L4 is on the schematic, just labeled "L_MINI". I assume it's an inductor of some kind.

Powering via USB heats up U2, and doesn't illuminate the 3.3v LED. need to find a powersource to connect to the 3v line to test that further

Parts that seem to need replaced:
U2 - AP7361C-33E-13 - Visible burn marks
U3 - A4403 - I've heard that this can go bad with a 3v short, no visible damage
U10 - W5500 - Visible burn marks
L4 - ?? - Seems cracked, Burn marks
SDCard - Corrupted, will not connect

[micle546]

[dc42]

@micle546 remind me on Monday when I am back from formnext and I will look up L4. It's probably the same component as one of the inductors on the Ethernet module for Duet 2.

The W5500 chip is typically the first to fail when there is over voltage on the 3.3V rail. I suggest you remove the two failed ICs and then power up and check the voltage on the 5V rail. If that measures OK you could either replace the removed 3.3V regulator, or apply 3.3V externally, then see if the USB port appears. If so then run M122 to see if the stepper driver status is OK.