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Yeah, I tried swapping the RA and DEC motors over. Same thing happened. The DEC motor on the RA axis slewed perfectly, but the RA motor on the DEC axis stalled. So I guess it cant be the motor.
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Ok, so a cable swap did nothing. Tried a few other things also. So:
The DEC motor stalls in the DEC port under no load.
The DEC motor stalls in the RA port under no load.
The RA motor works fine in either port under full load.
To me it sounds like a motor issue??
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Erik,
I certainly know NIL about the Gemini system but I know a little about steppers.
Brendan sounds on the money...it may be the bridge driver circuit on the
DEC axis has a component fault or simple connectivity problem.
It's also a little difficult to understand your two posts above...
Don't they sorta contradict each other?
One other thing, the tiniest piece of metal inside a stepper when
fouled against the spinning rotor permanent magnets and stationary
outer metal cage with the windings will cause these stalls.
Can you spin the motor freely? You will feel a smooth 'lumpiness' or
friction as it settles on it's 'steps'.
If there is metal or grit inside it will grab randomly.
Moisture/rust in the bearings (motor)will do this too.
Edit: Ahhh I followed Brendan's links....Hmm it has brushes
and an outer permanent magnet!....Hmm, what sort of stepper is
that?!!! Is it simply a DC servo/motor with encoder feedback for speed control???
FWIW.
Steve