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Author Topic: Gecko Tuning Problems  (Read 1813 times)

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Gecko Tuning Problems
« on: December 26, 2014, 09:02:53 AM »
I'm having trouble getting a Gecko 320 driver/motor to stabilize.  It worked fine before, but after doing some rewiring at the motor, I can't seem to get the vibration adjusted out of it.  I have the limit clear up as Gecko recommends and as usual for my setup.  I have 90V servo motors. 
The only position of the gain and damping pots that give me good performance with no chatter, etc, is with both of them fully counterclockwise.  BTW, the Gecko spec doesn't say which direction is full on.

I know that if you tune by ear, you turn the gain up until chatter, then turn damping up until it stops; then turn the gain up, then the damping until you're almost to the end of the damping pot.  Doesn't seem to work that way, both pots ccw seems to be the only working position.

I haven't dinked with the other two drivers since I set the system up months ago; scared to at this point.
Re: Gecko Tuning Problems
« Reply #1 on: December 26, 2014, 08:49:17 PM »
First clue... why did you rewire it if it was working ok?? Change the wiring back to the original wiring configuration. It's possible you have the motors mis-wired.
Re: Gecko Tuning Problems
« Reply #2 on: December 26, 2014, 09:51:32 PM »
Needed to clean up routing.  Just the two motor leads were impacted.  Put them through a new port in the motor housing and plugged the spades back together.  Connection is correct.  This (y) axis has always been a little on the edge, sometimes chattering on transition.  After rerouting the wire, it apparently went over the edge and I had to mess with the pots again.

My issue is that the pot adjustments don't behave as I would expect, particularly given that I seem to get good stable table movement only if the trim and gain pots are fully counterclockwise.  What the Gecko spec doesn't tell me is whether fully counterclockwise is full on or full off.  If full off, why does the table move at all?  Tried calling Gecko and they are out for the holidays.

I'm a retired EE and quite familiar with servo systems.  However, I'm looking for some experienced knowledge on the Gecko 320, so I can understand why it's behaving as it is.  So, two questions...

- Is ccw on the trim and gain pots full on or full off?  BTW, the limit pot seems to be full on clockwise.
- How sensitive is the system to the motor wire?  My wire is rather long.  The pair is tightly twisted all the way from the 320 to the motor.  There is a balun in each lead at the motor.

Grateful for any helpful feedback.

thanks, rex