I have a marginal workshop and a lot of birds called flickers, which serve the same niche as woodpeckers elsewhere, so the flickers punch holes in the workshop walls, and then squirrels move in and eat the wiring and circuit breakers start tripping.
I’ve no idea what they managed to eat the other day, but: I have the CNC mill electronics (stepper drivers) plugged into one outlet on one circuit, the CNC controller (computer) plugged into another on the same circuit, and the mill spindle plugged into an entirely different circuit to help cope with its noise. (Different phase, even.)
I was touching the case of the PC that runs the software, and reached over and touched the heatsink that the stepper drivers are attached to because they were suddenly acting very weird and moving randomly, and got a 110V shock from hand to hand.
I recommend against this. I felt kinda crappy for the next couple of days.
Anyway, in trying to autopsy the results, it appears that the PC itself still runs, and that the eight outputs (this is a parallel port based, linuxcnc install) all still have the right waveforms, when attached to my scope: about 20khz square waves with about 2% duty cycle, at 5V peak to peak, which is consistent with the settings.
The Gecko stepper drivers, on the other hand, are holding the steppers solidly (which made me think they were working) but aren’t accepting input. If I apply a 5V PWM signal to them, they don’t do anything (nor do they react to the output of the parallel port.) So I’m afraid I’ve cooked them. (Also interesting: they have a 36V input, but if I look at their outputs into the stepper motors, there are nonsense values with a DC measurement, and if I switch to AC, it’s showing about 90VAC. They are choppers, so maybe that’s not broken, but… they don’t have inductors or very big caps, so they shouldn’t be able to boost, which makes me think this is something involving some of the FETs blown and the inductance of the steppers themselves, like only the high side of the FETs are working.)
So it looks like I need a whole new drive system.
I could get a Gecko 540, which has all four drivers I need in one big package (and I believe with optoisolation on the inputs.) I could also get some of those neat newer closed-loop feedback hybrid stepper motors. Anyone have any experience with them?
This system isn’t huge: each stepper is about 6A per phase. So any other suggestions would be welcome.