Advanced Search

If Step/Dir resistor networks or driver chips are being damaged
it means a voltage considerably outside the 0 to 5V range is being
applied to the Step/Dir pins.

First thing I would check is drive grounding and Step/Dir wiring
Routing step/dir lines parallel to servo motor wiring might also
cause enough EMI to damage the drivers.

An intermittent short to 24V wiring is another possibility.