Re: Blown Gecko 340

Hi Andy,
It's either as Jon said, or there must be something odd in your
wiring or grounding. I've had numerous dialogs with customers in my
repair days like this, and usually it ended up being something
questionable in the construction. Post a high res picture of your
control wiring.

Things like oxidated fuse holder contacts or bad connections could
cause spikes that could damage the drive. Enough people have these
drives functioning perfectly and your voltage requirement is way in
the green on your setup. It should be darn near impossible to blow a
drive at such a low voltage. Is there anyway that the wiring to the
motors could be grounding to the frame, or is that motor( or wiring)
a drive killer( is it the same motor causing the damage?). A good
( pulling values out my mental oriface :-) )quality .1uF cap and
5ohm/10watt power resistor in series placed across the motor
terminals will act as a 'snubber' for brush noise and would be
a test. Get( or borrow) a battery powered scope ( or plugged into
isolation transformer!! ) and see what the voltage waveforms driving
the motor look like in real time. If you see huge 100volt fast
spikes, you've got brush issues or contact issues.

-Lee

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "andyolney" <andy@o...> wrote:
> Jon wrote:
>
> > Yup, clearly LOTS of head room. I'm starting to think it may be
a
> > > bad motor with an intermittent short. Just another thought, is
> this
> > > the SAME gecko drive that was repaired before? Maybe there is
an
> > > intermittent problem in the control logic that was not fully
> > repaired
> > > before?
> > >
> > > Jon
>
> Jon - I tested the motor with a 1.5vdc source with an ampmeter in
> series. Turned smoothly with no hesitation and the meter was very
> steady at .12 amp. FWIW the resistance of the motor is 2 to 6 ohms
> depending on the armature position. Resistance between motor leads
> and case was higher than the meter could read. Fluke 77.
>
> Any thoughts? Andy