Re: Stepper sings, but wont walk....

Thanks all,
I'll check the voltage from the transformer, I'll check the wiring
integrity...but Mariss, what is a phase transistor? Is that the
rectifier?

Thanks
Sean

--- In CAD_CAM_EDM_DRO@y..., "mariss92705" <mariss92705@y...> wrote:
> Hi,
>
> Try running the motor at a very low speed, just a couple of steps
a
> second. If the motor takes 3 steps forward and a big step back,
you
> have a blown phase transistor. You can identify it it with an
> ohmmeter. Measure the rasistance collector to emitter. A bad one
will
> show up as a near-dead short. Replace it and it may fly.
>
> Mariss
>
> --- In CAD_CAM_EDM_DRO@y..., "audiomaker2000" <audiomaker@s...>
wrote:
> > Hey all,
> > I have been trying to repair a Bridgeport Boss that has a
stepper
> > which when told to move via the stock control "sings" and will
sort
> > of vibrate but wont actually turn. I've replaced every card in
the
> > machine with those which I pulled from my retrofit machine (and
> > which are known to work), and the result is the same. I checked
> the
> > motor itself by switching it to a different axis circuit and the
> > stepper works fine.
> > So, I'm wondering what else besides the cards (drives, and stock
> > CNC) that could cause such a condition? I'll probably just
> retrofit
> > this one too, but it is making me quite curious. All that seems
to
> > be left is cap's and wires.
> >
> > Thanks
> >
> > Sean