extruder stepper grinding

[jimc]

back in business! rick and the crew were nice enough to ship me off a new extruder cable which i installed today. works fantastic now. thanks again makergear support!

[Dale Reed]

. there is quite a bit of current running though that wire. more than i would expect. the whole connector was flashing blue.

jimc, I don't know that there's that much current, but welcome to the wonderful world of inductors and back-emf! When you open the circuit when an inductor is carrying current (and especially when other nearby inductors are carrying current!), the magnetic field collapse generates an nice high voltage, capable of creating a lovely blue arc. Also quite capable of damaging the MOSFETs on the RAMBo. You're lucky that loose wire and those pretty blue arcs didn't kill the board. Hence the advice to NOT connect or disconnect the stepper motors when the M2 is powered.

Fortunately the bed heater is resistive, not inductive. It would be really nasty (and impressive!) if the current going through the bed heater generated an inductive arc flash when a wire at the back of the bed broke from flexing.

My point? Unplug the M2 and let it power down fully before you start unplugging any of the connectors anywhere in the unit.
Dale