Burnt Stepper Driver???

As you've no doubt realized from my many posts I'm the proud owner of a new duet wifi thats powering my custom delta. Yesterday I realized I had some skipped steps so I checked the recommended motor current for my motors and was surprised to find I was only running them at 50% recommended current. So I changed my config to reflect that, as well as some other tweaks, like setting microstepping (my config had no M350, so I added what I assume it defaults to anyway, 16 16 16 I1). When I powered up my towers ran great, but my extruder wouldn't turn. (same motor as towers!) I unplugged the duet, swapped the wires for my Y tower with my motor, powered up, now the tower won't move and the extruder does. Thinking I must have screwed something up regarding the extruder in the config, I reverted to backup, still nothing. Then I switched the tool definition to the 5th driver (leaving the heater and thermistor, steps/mm, current, etc settings the same) and everything works fine. The only possible explanation is the 4th stepper driver is shot right??? The unit is fairly brand new, I've taken extreme caution not to short anything, never unplug motors without cutting power, etc. What could have caused this??

Worse yet, I don't think I can send it back. I purchased it from Filastruder after being shipped a defective .85 board. On that board there was a missing/faulty solder joint on the ethernet port, and for the cost of these boards, I didn't feel it was worth the risk to solder it myself. They indeed processed the return and were nice about it, but we needed to get authorization from the maker of the board etc. Now for me to turn around and send back the duet wifi it starts to look like a pattern although it should be visibly clear on the first board that there was a faulty solder joint, I don't know how'd they differentiate a defective board from an abused board in this blown stepper case.

For the time being its no big deal because my delta is only single extruder. I did have plans in the future for a motorized flying extruder though (raised and lowered by a motor based on layer number, or a dual extruder setup, neither of which I can do without another stepper driver.

1) Am I correct that my driver is shot
2) Any way to fix it?
3) Any idea if I can prove this isn't my doing and get a replacement
4) Alternative solutions if I can't? External stepper driver? Duex2/5?

Thanks in advance.

Edited 1 time(s). Last edit at 12/11/2016 05:15PM by clearlynotstefan.

If I can't get it swapped out, how about replacing the stepper driver chip itself? It looks like I could snip the old chip out and potentially solder the remaining feet onto the new chip, or desolder the chip entirely and through-hole solder in a replacement. The chips themselves look pretty cheap! (edit: I'm not home with my board, I can't recall if the chips are even through-hole soldered or not)

Edited 1 time(s). Last edit at 12/11/2016 03:54PM by clearlynotstefan.

I really don't think Filastruder will blame you for returning the board with the Ethernet fault, so I suggest you ask them if they will either swap the board or get the driver replaced without charging you. The worst is that they will say no.

The driver is an SMD chip and you would need a hotplate and a hot air desoldering tool to replace it. There is a user on this forum, W3DRK, who can replace chips on Duets and is based in the US.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].