Re: Motor stall

Christopher Erickson

In my personal experience, the top ten most common sources of AP mount motor stalls (orange LED) are, in order:

1. Battery power voltage drop.
2. AC-DC power adapter failing for some reason. Usually due to internal age/humidity/corrosion.
3. Loose, fragile or corroded power connections.
4. Internal CP4/5 horizon limits safety feature hit. Sometimes the CP4/5 itself seems to lose track of the true horizon for mysterious reasons.
5. Camera/focuser/etc. cable hangup.
6. Pinched/damaged Motor Y-cable.
7. Loose motor Y-cable connections.
8. One or both axes BADLY out of balance.
9. Forgetting to put on the counterweights. (seriously yes, I have done this)
10. Electrical or mechanical failure of some kind in the motor assembly. Rather rare.

"Always take the high road. There's less traffic."

-Christopher Erickson
Observatory Engineer
Summit Kinetics
Waikoloa, Hawaii

On Sun, Jul 3, 2022 at 7:16 AM thefamily90 Phillips <thefamily90@...> wrote:
Agree. I should’ve taken my time but the seeing was so good I was more interested in viewing than isolating the problem. I will work on that in the future. 

Jim P 

From: <> on behalf of Tom Alderweireldt <tom.alderweireldt@...>
Sent: Sunday, July 3, 2022 12:50:31 PM
To: <>
Subject: Re: [ap-gto] Motor stall
Indeed check all the power cabling seems the obvious thing to do, one at a time to make sure you find the culprit.

After a recent chip upgrade on my AP1200CP3, I saw a 'motor stall' message when testing the keypad, but quickly figured out I forgot to reconnect the Y-cable to the CP3 control box, so that's not really a stall, but simply no power connection. That also seems to trigger the 'motor stall' message. Probably any slightly loose power connection or maybe low voltage could cause it.
(Although all AP cabling, wiring and connectors seem very robust) 


On 7/3/22 6:04 PM, thefamily90 Phillips wrote:
Is there a common denominator for motor stall? I was out observing Jupiter this morning and every once in a while, the RA axis would jump westward a few degrees and then there would be motor style. I changed cables, keypads, computers moved counterweights on RA axis, tightened RA when somehow, finally, I seem to have gotten it working without stalling. But I'm not certain what caused the stalls to begin with.

Any thoughts?

Jim P

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