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CP4 vs CP2 motor stalls?


Tom Blahovici
 

Hi
I frequently image during cold temperatures with my AP600.  A few months ago I updated to a CP4 from a CP2. Two days ago, the temperature was -12C and I received two motor stalls during slewing. In the past I could work at -25C and never got motor stalls. I have low temperature grease in the mount as per APs recommendations.
Is there away I can minimize this occurance?
Thanks.


michaeljhanson@...
 

Hi Tom,

There are several things you can look at:
- Do you know what version of CP4 software you have?  There have been a few changes related to stall over the years.
- Are you using the same power source as you did with the CP2?  And, is that power source adjustable? It is possible that a little higher input voltage will help the system to maintain the slew speed.
- Is the CP4 slewing at the same rate as the CP2?  The slew rate can be reduced to reduce stall occurrences at a given input voltage.
- Gear mesh can have a dramatic affect on the motor loading, make sure it's not too tight. See  600EGTO - Adjustments to Remove Worm Gear Backlash,
 at https://astro-physics.info/index.htm?tech_support/tech_support_legacy.  It also discussed mesh.

Regards,
Mike Hanson


Christopher Erickson
 

There are some safety limits in the CP4 that could have a bug in some firmware revs that look like a motor stall but aren't. Make sure to be using the latest firmware rev.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Thu, Dec 17, 2020, 5:52 AM <michaeljhanson@...> wrote:
Hi Tom,

There are several things you can look at:
- Do you know what version of CP4 software you have?  There have been a few changes related to stall over the years.
- Are you using the same power source as you did with the CP2?  And, is that power source adjustable? It is possible that a little higher input voltage will help the system to maintain the slew speed.
- Is the CP4 slewing at the same rate as the CP2?  The slew rate can be reduced to reduce stall occurrences at a given input voltage.
- Gear mesh can have a dramatic affect on the motor loading, make sure it's not too tight. See  600EGTO - Adjustments to Remove Worm Gear Backlash,
 at https://astro-physics.info/index.htm?tech_support/tech_support_legacy.  It also discussed mesh.

Regards,
Mike Hanson


Tom Blahovici
 

All firmware is up to date and all power supplies etc are the same as previously with my CP2.  I will lower the slewing speed which I think is at 600.
Thanks, Tom