AVX - Have you seen this motor behavior?? - Need Advice

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jthommes
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AVX - Have you seen this motor behavior?? - Need Advice

#1

Post by jthommes »

OK, this has happened to me twice now - first with the DEC motor; most recent with the RA motor...

The beginning of a session; turn on the mount; go to the align process; DEC axis motor doesn't run - crickets. No sound whatsoever on that motor. Cycle the mount power - no change - RA motor runs as expected the DEC is silent. Take off the motor board housing - inspect - nothing looks awry. Re-seat internal connectors - no change. After an hour of retrying these steps -no change. Pack it in for the evening take the mount off the observatory pier to troubleshoot at home. Two days later, get the mount ready to troubleshoot, ....And... the mount motors work perfectly!!

With nothing more to do on troubleshooting, take the mount back to the observatory. It works flawlessly for several months and many sessions.

Last session out, the RA motor does the same thing - crickets - while the DEC motor runs as expected. Follow the same steps as before but no joy. I even check the motor board fuses - they all read intact. Take the mount home to trouble shoot . This time I try trouble shooting the next day (about 18 hours after the initial failure and again about 22 hours) - the failure persists - the RA motor is silent; the DEC motor runs fine. I even tried resetting to the factory defaults - no change. I get a good nights sleep. Next morning (about 40 hours after this last failure) I gather some troubleshooting tools (meter, clip leads, etc). I power up the mount prior to begin trouble shooting, ...And... the mount motors work perfectly!!!

I have mixed feelings of relief and frustration. I haven't taken it back to the observatory yet, but I expect the motors will run fine.

I have had this AVX since 2014 and it has been my secondary (small refractor) astrophotography work horse setup since then - working pretty much flawlessly. So I got to thinking about "what has changed" during this summer when these two problems occurred? I have used this mount connected to the same computer. The mount gets commands from SGP and PHD2 as well as a planetarium program (first The Sky, now Stellarium). Here is what has changed:

1. I updated the Celestron mount ASCOM driver for the mount before the first failure. This is the update that fixes the SGP centering accuracy (includes time offsets for goto from a single direction). This was a pretty mild update. I don't expect this is the cause.

2. I did start recently checking all my connections to my laptop (camera, FW, guide camera, focuser, and mount) in daylight prior to the evening session just as a pre-check. For both failures, I inadvertently left the PC connected to the HC RS232 port when I powered down the mount. The three PC apps were still connected to the mount at mount power down and stayed that way for an hour or so (while the apps were presumably pinging for a connection or issuing commands to an un-powered RS232 port on the mount's HC). I know RS232 ports are notorious for sneak path powering of internal circuitry. I can't tell if that is happening here or if the mount HC and/or MC firmware are responding in an unintended manor to this condition.

I suspect item number two above is the root cause - but it is unproven. It could be that some internal Firmware feature is setting some timeout that persists at power cycle. That timeout being somewhere between 22 and 40 hours). The problem is that I can try to repeat and confirm this mode, but it shuts me down for something between 22-40 hrs.

Questions:
1. Has anyone else experienced similar failure and then miraculous recoveries?
2. I would love to prove root cause, but I am not willing to try to re-create an undesired operational mode that is unaffected by power cycling (or anything else I tried). Does anyone know if there is an internal reset pad or jumper that sets a "pristine" condition for the next power up (so I don't have to wait 22-40 hours to run again)? Does anyone know if I pull the lithium coin battery for a sufficient period if this creates a "pristine" condition that allows me to restore motor operation at next power up?

Helpful information: HC firmware 5.21.2336; MC firmware 6.07
Jim Thommes
Jim's Astrophotography
David Levy Maksutov Newtonian, Celestron Edge 9.25, FSQ-106N Refractor (on loan), WO ZenithStar 66 APO Refractor
G11/Gemini GEM, Celestron Advanced VX GEM
ST8300M Camera, Atik 383L Camera, Canon 350D Camera, ASI1600M, ASI 294M
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Re: AVX - Have you seen this motor behavior?? - Need Advice

#2

Post by SkyHiker »

Have you swapped the DEC and RA motor cables?
... Henk. :D Telescopes: 6" Mak-Newt (Comet Hunter), ES ED127CF, ES ED80, Zhumell Z12, AT6RC, Venture RX-7, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with DIY OnStep, AVX, LXD55, Tiltall, Cameras: Fuji X-a1, Canon SX40, Xt, XSi, T6, ELPH 100HS, DIY: OnStep controller, Barndoor trackers for 10" Dob and camera, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK
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Re: AVX - Have you seen this motor behavior?? - Need Advice

#3

Post by turboscrew »

The symptoms brought dew into my mind.
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Re: AVX - Have you seen this motor behavior?? - Need Advice

#4

Post by Lady Fraktor »

Possibly a loose connection in the mount or cable. I would check the cables as well.
Have you tried using the hand controller to see if it is presenting a Error 16 or 17 message?
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Re: AVX - Have you seen this motor behavior?? - Need Advice

#5

Post by SkyHiker »

SkyHiker wrote: Thu Sep 17, 2020 2:29 am Have you swapped the DEC and RA motor cables?
Ah there is no RA cable on the AVX, sorry I forgot. Tweet the DEC cable for problems, or crimp a new one and see if that fixes it.
... Henk. :D Telescopes: 6" Mak-Newt (Comet Hunter), ES ED127CF, ES ED80, Zhumell Z12, AT6RC, Venture RX-7, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with DIY OnStep, AVX, LXD55, Tiltall, Cameras: Fuji X-a1, Canon SX40, Xt, XSi, T6, ELPH 100HS, DIY: OnStep controller, Barndoor trackers for 10" Dob and camera, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK
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Re: AVX - Have you seen this motor behavior?? - Need Advice

#6

Post by jthommes »

Hey, thanks people for the responses to my incidents. I have individual responses to each.

turboscrew wrote: Thu Sep 17, 2020 4:00 am The symptoms brought dew into my mind.
Thanks for the suggestion. So my observatory (where both of these incidents have occurred) is in the California high desert. These both happened under pretty dry conditions. I think the max humidity was about 30%; temperatures were from 22 to 27 C. See my summary below.

Lady Fraktor wrote: Thu Sep 17, 2020 5:20 am Possibly a loose connection in the mount or cable. I would check the cables as well.
Have you tried using the hand controller to see if it is presenting a Error 16 or 17 message?
So I am a bit confused. The hand controller was always used - the PC RS232 port is on the hand control. Its where the RS232 buffers/level shifters interface the PC to the AVX internal communication channel. But no, I did note see a "No Response" (error 16 or 17) indication from the hand control. What I see is the little spinner in the upper right of the HC display continues to spin after I release the slew button. Normally this only spins when the motors are slewing the mount. So the HC looks like it is trying to (or thinks that) the motor is driving. Your comment did have me research a little more info - see the summary below.

SkyHiker wrote: Thu Sep 17, 2020 2:02 pm
SkyHiker wrote: Thu Sep 17, 2020 2:29 am Have you swapped the DEC and RA motor cables?
Ah there is no RA cable on the AVX, sorry I forgot. Tweet the DEC cable for problems, or crimp a new one and see if that fixes it.
Yeah. Well I could disassemble the whole mount and physically swap the motors. By that time I think the AVX would have recovered. See the summary below

SUMMARY:

I probably should have been more emphatic about the PC connection issue. ...

Twice I have forgotten and inadvertently left the HC RS232 port on the AVX connected to the PC with active apps connected to the AVX when I powered down the AVX. I (again inadvertently) left the setup in this state for an hour or so. Each time this active connection was left on the un-powered AVX, a motor did not operate upon powering up the AVX again. Once it was the DEC motor and once the RA motor that was silent and did not run for the rest of the evening session. The only times the motor have not worked on this AVX was when I inadvertently left this connection in place. This was a 100% correlation in both directions (admittedly only a sample of two). What I don't have is a validated root cause for this correlation. Obviously I will endeavor to not make this connection again unintentionally. But I don't want to have to wait the 20+ or so hours to have the quiescent motor become active again.

When these incidents did occur, I cleaned off and re-seated cables both internal and external; checked power (17 AH battery - 12.95 volts); cycled power; performed factory reset. None of these had any impact. If I waited 20+ hours, the problem resolved.

I was looking at the NexStar Resource site and see some interesting information about HC communication to the two motor controllers (and among other things like AUX Ports, RTC, GPS, etc). These all share the same communication channel and that the Hand Control RS232 port essentially is this same channel with RS232 buffers on the front end. So my inadvertent active connection to the HC RS232 port upon AVX power up may be disrupting initial communications to the Motor Controllers. I will contact this site to see if they have any more information or insight.

So What I really want is a process that allows me to remove the long wait time to have the motor operate again. The site suggests that a non-working MC may be in "boot mode". Reloading the AVX FW in some cases is needed to solve the "boot mode" condition. This was in the "No Response" (error 16 or 17) article. While this is not my issue, I want to ask them if this seems like a potential approach to doing an immediate fix to my issue without having to wait the extended time.

If I get encouraging information or if I am able to do more testing (ether root cause or immediate recovery), I will get back to this thread to update it. (It may be awhile ;) )
Jim Thommes
Jim's Astrophotography
David Levy Maksutov Newtonian, Celestron Edge 9.25, FSQ-106N Refractor (on loan), WO ZenithStar 66 APO Refractor
G11/Gemini GEM, Celestron Advanced VX GEM
ST8300M Camera, Atik 383L Camera, Canon 350D Camera, ASI1600M, ASI 294M
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Re: AVX - Have you seen this motor behavior?? - Need Advice

#7

Post by turboscrew »

What made me wonder was that 20+ hours and "self fix". What could happen in 20+ hours, but not in, say, 5 hours.
If you find it out, please report here.
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Re: AVX - Have you seen this motor behavior?? - Need Advice

#8

Post by SkyHiker »

What happens if you shut down the computer and reboot? Shut the AVX down, factory reset. I don't think the AVX or the PC have a memory of the connected state that persists through a reboot.
... Henk. :D Telescopes: 6" Mak-Newt (Comet Hunter), ES ED127CF, ES ED80, Zhumell Z12, AT6RC, Venture RX-7, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with DIY OnStep, AVX, LXD55, Tiltall, Cameras: Fuji X-a1, Canon SX40, Xt, XSi, T6, ELPH 100HS, DIY: OnStep controller, Barndoor trackers for 10" Dob and camera, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK
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Re: AVX - Have you seen this motor behavior?? - Need Advice

#9

Post by jthommes »

turboscrew wrote: Fri Sep 18, 2020 3:45 am What made me wonder was that 20+ hours and "self fix". What could happen in 20+ hours, but not in, say, 5 hours.
If you find it out, please report here.
Will do. I have registered on teamcelestron.com. I hope to get approved so I can post this issue.

It is so strange. Although with only two data points and extreme difficulty in investigating (time duration for resolution), it could still be something physical. The behavior has been consistent for these two points. I am a retired electrical engineer (FPGA code development). My experience has been that seemingly random failures often turned out to be systemic code errors not the other way around (consistent failure signatures caused by random issues).
Jim Thommes
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David Levy Maksutov Newtonian, Celestron Edge 9.25, FSQ-106N Refractor (on loan), WO ZenithStar 66 APO Refractor
G11/Gemini GEM, Celestron Advanced VX GEM
ST8300M Camera, Atik 383L Camera, Canon 350D Camera, ASI1600M, ASI 294M
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Re: AVX - Have you seen this motor behavior?? - Need Advice

#10

Post by jthommes »

SkyHiker wrote: Fri Sep 18, 2020 11:07 am What happens if you shut down the computer and reboot? Shut the AVX down, factory reset. I don't think the AVX or the PC have a memory of the connected state that persists through a reboot.
I shut down the computer and completely disconnected it. Repeated restarts of the AVX resulted in motor behavior of not running. At least until an extended (20+ hrs) time period transpired. Same thing goes with the factory reset (for the second incident - PC still totally disconnected). Then after waiting an extended time and still under the factory reset configuration the motor runs. I re-established my original settings after the motor started operating; connected up the PC and everything continues to work at this time.
Jim Thommes
Jim's Astrophotography
David Levy Maksutov Newtonian, Celestron Edge 9.25, FSQ-106N Refractor (on loan), WO ZenithStar 66 APO Refractor
G11/Gemini GEM, Celestron Advanced VX GEM
ST8300M Camera, Atik 383L Camera, Canon 350D Camera, ASI1600M, ASI 294M
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