Re: Interesting Servo Motor Encoder Problem

Hi,

My guess is the encoder head drew way more than the 50 mA max current
from the G320. This may have pulled the +5VDC out of regulation,
causing the motor to take off. Was the LED unusually dim?

Mariss

--- In CAD_CAM_EDM_DRO@y..., "Dan Mauch" <dmauch@s...> wrote:
> I recently came across an interesting servo motor encoder problem.
I had
> installed an Us digital encoder onto a servo motor and after
centering
> the code wheel and installing the Agilent read head I tested the
servo
> motor and encoder on one of my older Gecko G320 servo amps. When I
> powered up the servo amp the motor took off running at very high
speed
> then gradually slowed down. When it stopped the motor had no torque
and
> then faulted out. I rechecked all the connections and motor/encoder
> polarity and everything was fine. I connected the motor to a
separate
> power supply and it ran fine. So I knew the problem was either in
the
> old gecko or the encoder. I changed the motor out with another motor
> with the same type of encoder. It ran perfect and the encoder worked
> perfect. Now I knew that the G320 was good. Then I took apart the
> encoder on the dective unit and reassembled it again verifying
that the
> wheel was running true was the proper height and that it was
> mechanically centered to the read head. Everything was perfect but
upon
> retest the same high speed start was noted and loss of torque. So I
> trundled out to my shop took apart the encoder for the third time
> reinspected everything and concluded that it had to be the read
head was
> bad. After verification that indeed the correct read head was
supplied I
> replaced the read head with a different one and reassembled. This
time
> it ran perfectly tracking just like it was supposed to.
> So this is probably a rare problem because I have probably installed
> several hundred of these read heads and never found a bad one. What
was
> really weird was that something internal to the encoder read head
must
> have been acting like a pulse generator to cause the motor to spin
and
> then slow down.
> Having fun
> Dan