Re: Servo amp connections needed. Where should I go from here?

Hey Thanks Chris,
There is no tach on the motor I am using.This is a mishmash of
parts.I was trying to simulate the tach input at the same time as the
signal hoping it would null out somewhere near zero volts on each
input. It may be a case where I need a slight negative to null it.
You are correct in stating there is a + and - 10 voltDC terminals.
I was considering putting a 2k pot as a variable voltage divider
across these +/- terminals to get a 20volt spread with 0 volts at
center.Then using the pot wiper as the output to the signal and tac
inputs respectively. Without the book it will be difficult to
determine what the polarity should be other than a common is nearest
the tac input. The only problem I see here is the 20volts seems a bit
high for the input signal. Not out of line for the tach if 7v=1000
rpm so 20volts would be 3000RPM.
There are also some pots on the board. The obvious ones are for
current limit and servo response. The other 3 have something to do
with the inputs of the signal and tach sensativity. They are only 1/2
turn pots. Not like the 10 turn pots on other amps I have tuned in
the past.


That is about all I have to go on.

DC

--- In CAD_CAM_EDM_DRO@y..., ccs@m... wrote:


>
> You need to hook up the tach to a tach on the motor, getting the
> polarity right (ie, if it takes off swap the tach or motor wires)
and
> then try putting an analog command voltage into the input. There
may
> a pot you can tune for a slight offset, but you will really need to
> find positive and negative supplies if you want to run it with a
> pot... you ight be able to find the voltages in the drive somewhere
> to borrow for testing purposes.
>
> Chris
>
> > I have a servo controller that I can't seem to find any
information
> > on.
> >
> > It is manufactured by Control Systems Research, Inc. Pittsburgh,
PA.
> >
> > The model is NC121F.
> >
> > My question is in trying to get control of a servo motor with a
> > single or stacked potentiometer.
> > The controller has signal and tac inputs. I do not know what it
is
> > expecting at these inputs. My first guess was 0 to +10v at both
> > terminals in relation to the common. I don't really have 0 to -
10v so
> > I am unaware if a null point could be reached this way.
> > My mode of thought here is that the tac may output 6-7vdc/1000
rpm.
> > If the inputs were tied together then they would track each
other.
> > Not so, or at least it did not prove out.
> > When I touch either the tac input or the signal input with one
wire
> > or my fingers. The shaft slows and stutters . Possibly the stray
ac
> > signal I presume from my overhead lights. Using another power
source,
> > it was found to reverse the motor direction by connecting the
signal
> > lead to ground.
> > Am I way off base in my mode of thought for bench testing this
> > setup?
> >
> > DC
> >
> >
> > Addresses:
> > FAQ: http://www.ktmarketing.com/faq.html
> > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> >
> > Post messages: CAD_CAM_EDM_DRO@y...
> > Subscribe: CAD_CAM_EDM_DRO-subscribe@y...
> > Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@y...
> > List owner: CAD_CAM_EDM_DRO-owner@y..., wanliker@a...
> > Moderator: jmelson@a... timg@k... [Moderator]
> > URL to this page: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> > bill,
> > List Manager
> >
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
>
> -------------------------------------------------
> Christopher C. Stratton
> Engineer, Instrument Maker, and Horn Player
> ccs@m... 617 628 1062
> http://web.mit.edu/~stratton/www/brassbuild.html