On Jan 1, 6:28*pm, wrote:
What do you mean with the term A/D as "A/D signal" and "A/D voltage"? You
sound, from context, as though the term D/A would be appropriate.
On another angle, you might look for a y in the path from the encoders;
one pathway to the displays and another to the control boards. Possibly
the pathway to the controller has it's own adjustments to accomodate
the change.

Hul

oldjag wrote:
On Dec 29, 4:11?pm, Dave B wrote:
On Mon, 29 Dec 2008 12:50:25 -0800, Dave B wrote:
Are the amps manufactured by Westamp?

Dave B

I have never worked on a Hurco, however it would seem there would be
parameters that allow you to alter the position loop gain.

Do you have parameters for backlash etc ?

Dave B
Dave;
The amps are Servomate Randtronics. They have the following Pot
adjustments: GAN = Gain, TAC = tachometer input, AUX=auxillary, (not
used), BAL=Balance, SIG=Signal and CLM=current limit. *Standard
preliminary setup is to MAX out, (20 turns CW) the CLM and the TAC,
set the BAL in the middle, adjust SIG to get the A/D out from the
servo control board to the Servo amps around 0.65V during a 20 in/min
feed, and use the BAL to get the voltage the sam in both directions.
Also the gain gets adjusted up to instability and backed off a few
turns. *The problem is with the base settings the servos are vibrating
like crazy. *Backing off the Sig kills the vibration, but with the sig
backed off to where the vibration stops, the servos are very slow to
respond, and the A/D voltage gets to only .45 volts. *Things checked
so far:
1.)Tach inputs to servo amp are okay and correct polarity.
2.)Encoder pulses look good on A, B and Z channels on scope at the
servo control board.
3.)Backlash on the ballscrews is less than 0.0002"
4.)Main cap on servo amp 80Vdc supply checks out okay.
5.) +12V and -12V Servo amp supply looks good.
6.) Position display is reading in the correct direction and is
accurate.
7.) A/D signal from servo amp looks noisy, but I don't know what
normal looks like.
At this point I'm not sure what to check next. *Vendor thinks maybe
problem is the new encoders, but I'm not convinced.

Yeah, sorry I mean D/A output from the Servo control card. The
backlash comp. is still set to the same values as before the board
upgrade when everything was working. The backlash is set on the
interface board on this machine. I also set the backlash comps to zero
with not change in the vibration issue.