RE: [CAD_CAM_EDM_DRO] Re: Servo or Encoder problem?

Renco encoder? If so that may be the problem. The gecko G320/G340 can
source up to 50 MA but as I recall the renco encoders draw 75MA. However
that doesn't explain why it works at low speed and not at high speed.
Dan

-----Original Message-----
From: mmurray701 [mailto:gmurray@...]
Sent: Monday, August 18, 2003 1:16 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: Servo or Encoder problem?


Jon, Thanks for the reply. The three motors are identical. All are
Electrocraft E543 motors with Renco encoders. The cabels are all
identical in both length and type. They consist of a shielded multi
conductor 22 guage cable for the encoder and just 16 guage lamp cord
(basic 2 conductor wire) for the motors.

I did get these servos used so anything is possible. I got in touch
with the guy who sold me them and he is willing to send me another,
but I'd still like to have this one working if possible. Nice to
have a spair in case anything breaks in the future.

So does this narrow anything down? Where should I go from here? Try
the capacitor? Seems to me that if noise were to be the problem then
it would also cause a problem on the other two since everything is
the same. Any other advice?

Mark

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:
>
>
> mmurray701 wrote:
>
> >I'm in the process of upgrading from steppers to servos and have
> >come across a slight problem. I've finished my control box
> >containing the power supply, Geckos and all the cables and tried
it
> >(on the bench) and everything seemed to work fine. After some
more
> >testing to today I noticed that one servo performs erraticly at
high
> >speeds. Two of them run fine up to nearly 4000 RPM but one seems
to
> >shake and cause the drive to fault after about 2000 rpm. This
> >problem is in the servo as I tried it on another drive/input. I'm
> >just wondering if its the encoder or the motor? Everything works
> >fine at lower speeds. What could be causing this? Thanks in
advance.
> >
> >
> Well, what is different about this one? Are they identical
motor/encoder
> units? Is the cable longer on this one? Is the cable of a
different
> type on
> this one? If it works at low speed, it is somewhat unlikely the
motor or
> encoder are bad. But, it is possible that the encoder,
especially, is
> marginal.
> Some people have had problems with noise on the encoder circuit.
One
> fix was to put a small capacitor, around 10 uF, across the 5 V
power
> connection, right at the encoder. Did you use shielded cable for
the
> encoder? If not, you might try that.
>
> Jon


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