I was happily machining away today when for no obvious reason the 5 amp
breaker inside the cabinet tripped and the spindle and axes stopped (this
breaker is located underneath the V Bus Pre-Regulator board).

So, twice I reset everything, restarted the program, and about 4 minutes into
the program trips.

I think the V Bus Pre-Regulator is part of the spindle motor control
electronics, but couldn't explain it's function. I checked the spindle
(free turning) and confirmed the motor spins free with the belt off. And that's where my unguided diagnosing skills end.

Any ideas?

mp-