Re: [CAD_CAM_EDM_DRO] trouble shooting steppers

In a message dated 14-Nov-01 16:26:01 Central Standard Time,
cadcamcenter@... writes:

> What are the proceedure for trouble shooting steppers which doesn't
> behave (eg. no reaction/hum but no movement/clicking sound but no
> movement) with
> a. only a multimeter
> b. frequency meter
> c. oscilloscope
>
>

Very basic! first, disconnected, there should be "continuity" in the
windings, and this would be very low resistance, between, oh, 1/2 ohm (not
counting lead-wires!), to maybe 50 or 100 ohms, depending on how high of a
voltage for which the motor is rated. If a "four wire", then there should be
a winding (continuity) between two pairs of two wires, each, but NO
connection between these two pairs of wires. (a-b, and c-d, but NOT a-c [or
b-d; same thing[). If a "six-wire", then think of the motor as having these
same two coils, but with "center-taps" on each, and higher resistance between
the "ends" of the windings than the "four-wire" of same size/torque.
Eight-wire? Now you have FOUR separate windings, and, well, typing is not MY
hobby!

Try spinning the shaft with your fingers. It should turn with no "feel" of
anything "crunchy", but it SHOULD have a very -perceptable "cogging" as the
toothed magnet rotor passes by the toothed stator, inside.

To check the driver, CONNECT it. with NO pulses sent, measure the voltage on
EACH wire to +common, and write 'em down. Now, send ONE pulse (either CW or
CCW; doesn't matter), and check these voltages, again. ONE coil should have
changed. If not, the DRIVER is kaput.

Lotsa luck. Jan Rowland, Troll


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