Low cost Servo drives +/-10V analog....and Camsoft.

This question may have been asked hundreds of times....
Looking for a source of servo drives that accept +/-10Vdc
analog input. Low cost (of course). The Advanced and Copely's
are a bit pricy IMHO. Elmo looks interesting, but they wouldn't
sell me 2 or 3, at reasonable prices. They deal in OEM quantities
only. Need something in the 80V 10/15A cont. size range.

Thanks

Shawn: How do you like the Camsoft product so far??

dan k





--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Shawncd" <shawncd@p...>
wrote:

> Thanks to everyone that responded...
>
> Jon,
> To answer most of your questions here is what I have done so far.

When I

> first got the machine home I installed a Advantech industrial

computer with

> a Galil DMC 1040 control card. Next I installed Galils servo tuning

software

> and Camsofts cnc software. As I tuned the servos for the new system

I

> noticed that Z wasn't working, so I diagnosed and found the servo

amp to be

> the culprit. After searching all over tarnation for the best price

on a new

> / used one. I found one that was identical, except for it has the

latest

> revisions. (electrically the board looks a little different from the
> original) After installing it I noticed that with just axis Z

plugged in

> there was silence. No whining noise, as with the other drives. So

that's

> when I started questioning the older drives. Maybe the older units

just

> sound this way because of the lower frequency. And the newer revised
> versions have the fix for this nusense noise. Or maybe the other two

are

> about to fry as well. Which would make sense because there all the

same age.

> Anyway, the other two older drives seem to function and hold

tolerance. But

> it started to make me wonder if I should start looking for two more

drives

> to replace the others. With hardly any support coming from Servo

Dynamics

> this was my next best place for info.
>
> Regards
> Shawn
>
>
>
>
> ----- Original Message -----
> From: "Jon Elson" <elson@p...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Tuesday, October 07, 2003 9:37 AM
> Subject: Re: [CAD_CAM_EDM_DRO] Servo Dynamics 1525 servo drive noise
>
>
> >
> >
> > shawncd2001 wrote:
> >
> > >I recently purchased an older Milltronics Partner mill. This
> > >particular unit uses the older Servo Dynamics 1525 servo drives.
> > >I have tuned the drives to where they perform the way I want

them,

> > >but there is an ear piercing whine or whistling sonund coming

from

> > >the boards. Anybody out there have the same problem? Any ideas on

a

> > >fix? Any information would be much appreciated.
> > >
> > >
> > >
> > Yup, these older drives have very low frequency PWM cycles, and so
> > produce lots of audible tone. Looking in the book, it says it is

16 KHz.

> > Most people past their 20's can't hear much up there anymore.

This would

> > be the same pitch as the horizontal output of a TV set.
> >
> > I'm wondering if what you are getting is a subharmonic or

unrelated

> > lower frequency than the 16 KHz? Can you make the pitch or

loudness

> > of the tone change by moving the axis to a different position, or
> > manually damping the shafts (motor, encoder, tach) with your

hands?

> > Can you make a guess at the frequency of the tone? Are you sure

it

> > is coming from the servo amp, and not the motor?
> >
> > You might also disconnect or disable all but one amp at a time to

see

> > if it is one particular amp, or all of them emit this tone. If

you can

> > disconnect the velocity command signal from the CNC control to
> > the amps, you can see if this is a positioning loop oscillation,

or

> > just in the servo amp.
> >
> > The Servo Dynamics does have inductors on the output. They appear
> > to be quite small, so it doesn't seem likely they are emitting

much

> > sound. There is a large transformer (T3) on the circuit board. I

have

> > only partial schematics of this amp, but I assume this is a DC-DC
> > converter that provides isolated power to floating circuits in the
> > amp. It may be running at an abnormally low frequency. Without
> > diagrams, I can't go much further. You could try wrapping foam
> > around this transformer, but if it already runs hot, that might

not

> > be a good idea.
> >
> > Jon
> >
> >
> > Addresses:
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