> First try James' method and let us know.  It'd be interesting to see
> how easy it is to feel a shorted winding.  If that doesn't work, you
> can identify windings with an ohmmeter.  Getting the phase and
> polarity right is more tricky.  If you've got few enough you can use
> trial and error.  The most direct method is to drive the stepper by
> hand and look at the phase relationship between the windings on a
> scope.

I have quite a collection of steppers and in most cases the difference in 
detent torque with a coil shorted or not, is quite noticeable. However, in 
one case, it wasn't. That was with an old 5" floppy drive motor. Probably 
the one most likely to be found surplus.
Needless to say, the ones with a gearhead are a problem.

Once the centre taps have been determined, the phasing is quite easy 
to determine for all but an 8 wire motor, as they are relative to each 
other. Call the coil end wires A, B, C & D. Try to run the motor at a very 
low step rate (eg.1 step/sec). If the motor steps back and forth, swap B 
& C. If it runs backwards, swap A & B.

Steve.


==========================================
Steve Baldwin                          Electronic Product Design
TLA Microsystems Ltd             Microcontroller Specialists
PO Box 15-680, New Lynn                http://www.tla.co.nz
Auckland, New Zealand                     ph  +64 9 820-2221
email: steve@tla.co.nz                      fax +64 9 820-1929
=========================================



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