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Help! demon possessed mount (random slew that won't stop)

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#1 t_image

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Posted 16 June 2019 - 01:36 AM

Just looking for maybe an overlooked simple solution, like menu setting or even DIY disassembly and repair without buying a new circuit board.

So my bottom-of-the line Nexstar alt/az with HC(the one that can take alkaline batteries)-but I use AC,

I don't know the name because I don't buy the mounts with the OTA (as it seems they are named by?).

I've been resorting to its use as the simplest setup just for hand controller tracking of moving objects, so no initial alignment done, etc...

Owning a few Celestron mounts, I've ruled out the particular hand controller so it must either be a menu setting, mechanical/electronic flaw,

or something I'm overlooking like an anti-cord wrap or median flip feature that I wouldn't think of....

 

So I've experience for a few years now completely intermittent sessions where the 'demon' would possess the mount.......

(to be clear, after trying to use the search term "possessed" and found quite a lot of uses in the forum referring to the mount "possessing" a certain feature,

I feel the need to clarify I don't mean the mount possesses the demon (as I don't imagine it a positive sell).....

 

As stated in the title, said "supernatural villain"flame.gif  will unpredictably and mysterious take control of the mount as if it had a HC of its own and-would 'depress an arrow key' and not let go......

The mount will endlessly slew towards a particular AZ direction and won't cease until I turn the power button off, often deciding to spin in altitude as well.

No response to any HC use during the event. Direction is not isolated to just AZ or ALT FWIW...

I find the hard-reset a quick fix. Then it works for a while....

Sometimes I forget it even has this flaw, will have episodes where it is completely reliable and will even track....

 

So short of calling a cleric for what I imagine has a more likely explanation that blaming entities,

I wonder if anyone else has an idea.

I've seen this:

https://www.cloudyni...unt-doing-this/

but my symptom is more severe, won't respond to HC. And only using HC, no wifi or tethered to pc...

 

Being that I am often interacting with the mount via movements, I don't recall it spontaneously just initiating from a stable tracking or on its own.

It's more like I'm slewing and then it decides it never wants to stop but additionally adds another direction as well (ie slewing AZ left, will then keep going but then start changing Alt as well).

 

Thanks in advance!

 

 

 

 



#2 Dynan

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Posted 16 June 2019 - 06:15 AM

Wow. With your extended experience, I'm at a loss for a diagnosis. My only guesses would be (an you probably covered these) is:

 

Check your power supply...low amperage/voltage can cause 'demonesque' behavior.

 

Have you done a full HC reset to Factory Settings? (You mention multiple HC's, so probably not this.)

 

How about a firmware check? Reload in CFM just to eliminate that possibility.

 

Please keep us informed.


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#3 mclewis1

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Posted 16 June 2019 - 10:30 AM

You mention an AC 12v power supply ... what are it's specs?

 

You'll need a regulated 12v supply rated at something like 2000-3000ma (more is fine too) and with a 2.1mm x 5.5mm power connector.

 

A power supply that's failing or one that's rated at a lower amperage will cause similar symptoms.


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#4 t_image

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Posted 16 June 2019 - 10:51 AM

Oh bitter. No quick "I'm a dummy" moment like I was hoping....

 

Good idea about power source. I should have mentioned I've experienced this irrespective of supply (inverted battery in field or wall plug at home or 12v cig lighter Celestron cord, with several different "Celestron" brand AC adapters. This is a wimpy mount so it doesn't draw much I figure.
As I force myself to describe the sit. I realized my use case might not be the norm(slewing regularly) which does draw more power.

Also happens independent of slew speed and not much weight on it (mirrorless camera w/85mm lens).

Maybe I'll take it out and play w/ in the daylight....

 

Oh  firmware. Never done an update because haven't needed it. I finally have a rs232 to usb so can try now, but will wait for that. I have personal ideologies on updates and firmwares that make me hesitant..

Will test it out some more.

Thanks for the thoughts!


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#5 chicagorandy

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Posted 16 June 2019 - 11:57 AM

 If you have eliminated the hand controller (and its cable) from being a possible cause -assuming you tested using various HCs and their respective cables - as well as the power supply, it seems to suggest an electro-mechanical issue inside the mount itself. Corroded contacts on the plug for the HC cable, wiring to the motors or some such.

 

I don't completely disagree with the notion of "If it ain't broke, don't fix it", but if NONE of the HCs you tested with have ever had firmware updated? Since something IS broke, it might be a sound move to update to fix it.

 

Failing that? The thing IS haunted and you need to call Ghostbusters.


Edited by chicagorandy, 16 June 2019 - 03:12 PM.

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#6 skaiser

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Posted 16 June 2019 - 01:13 PM

There have been a number of incidents where the direction arrows on the hc will stick.

But I believe you said you have tried a number of controllers.

so it could be a flaky connection in the mount.

if you search you can probably find how to take the mount apart to check wire/board connections.



#7 TelescopeGreg

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Posted 17 June 2019 - 12:34 AM

Dew?

 

I've had my AVX go nuts after tracking perfectly for a while (hour or so), then when I slew to a new target, it's either aiming a bit north of Manchuria (through the planet), or slews and then keeps going.  I've narrowed it down to either power (I'm using a Celestron 7AH PowerTank), or perhaps dew collecting inside the mechanism and confusing the sensors. 

 

Power has already been suggested.  I'm tossing in Dew as a wild card, but I'm kind of grasping at straws too.  There's another brand mount that's on sale this month, and it's tempting...

 

I know it's not inherent in the mount - it worked fine when new - so something has either aged or worn.


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#8 t_image

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Posted 17 June 2019 - 02:49 AM

Thanks for the added tips!

FWIW I brought it into the house and put it through its paces and got it to have a seizure!

This time I didn't have gear onboard, and just watched to see if it went to a stopping point. One time the alt motor did stop but the AZ kept spinning.....

 

Being the only mount I haven't taken apart, I went there.

Very simple innards. I considered maybe the jumper cable groups may have a faulty wire (like how cheap headphones wear out),

but it's not like these wires are put under much mechanical stress.

No sign of any visible cause. Did notice a little drop of soldier stuck to an insulated wire that betrayed QC I wouldn't do myself...

Maybe I'll break out my multimeter in a few day and check values.

I did check the max current of my AC power supplies and I do have one 2A and one 5A. Only used the 2A today.

I didn't take time to break out other HC's and will check the firmware listed in menus just FWIW.....

In the light of day I did notice the HC alerted an error code 16 no response.

After searching this evening,that led me to this thread:

https://www.cloudyni...-17-nexstar-hc/

Not completely applicable, but I found Mike's link helpful:

https://www.nexstars.../NoResponse.htm

 

So next I'll try methodically the AUX input recommendation, different power sources, different HC's, even PC control. Maybe even wifi, but I don't like the latency of the last two when tracking fast objects....

Note the problems are intermittent so it's a bit time consuming......

Sorry Greg for your AVX trouble. My first AVX was exchanged by dealer after going bad immediately (no HC display),

but I've had no trouble with my current one. AVX just a little overkill when this mini guy can do....FWIW I think its one of the SLT mount series, but it takes 2x9v, all the manuals for mounts that look like this one on the website say 8 AA batteries...

FWIW a 2 pin jumper is empty on the motor controller board, I guess an accessory power cable (say connector as the 9V plugs that come into the power switch board)....

I figure the boards are more universal than the models so don't think this is an issue....


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#9 Dynan

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Posted 17 June 2019 - 06:48 AM

Note the problems are intermittent so it's a bit time consuming......

As a retired Electrical and Instrumentation Technician, I can tell you this is the WORST kind of problem to run across. Simply because IF IT AIN'T BROKE, YOU CAN'T FIX IT!!!

 

If there's any way you can record readings, (voltage, amperage, etc.) at certain points, you can diagnose a failure. Else you have to 'be there when it happens'.

 

Disassembly and cleaning of all possible contacts with a mild abrasive (think ScotchBrite pad) might help.

 

Thanks for the update. You never know who'll have the same problem. And please keep us posted...I HATE half of a mystery...


Edited by Dynan, 17 June 2019 - 02:49 PM.

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#10 TelescopeGreg

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Posted 17 June 2019 - 01:53 PM

Sorry Greg for your AVX trouble. My first AVX was exchanged by dealer after going bad immediately (no HC display),

but I've had no trouble with my current one. AVX just a little overkill when this mini guy can do....FWIW I think its one of the SLT mount series, but it takes 2x9v, all the manuals for mounts that look like this one on the website say 8 AA batteries...

FWIW a 2 pin jumper is empty on the motor controller board, I guess an accessory power cable (say connector as the 9V plugs that come into the power switch board)....

I figure the boards are more universal than the models so don't think this is an issue....

Since your issue reproduced indoors, that's an indication that it's not a matter of humidity.  So, a good data point.  In fact, a worthy experiment to try myself. 

 

I've added a connector to the PowerTank so that I can daisy chain in a second battery pack, as a way to prove that the battery is or isn't the problem.  As Dynan notes, it's not until you can reproduce the problem that you can start working on a fix.

 

The AVX in my case is not overkill.  Underkill, in fact, as it's got some 27 lbs of telescope, guider, and camera to swing around.


Edited by TelescopeGreg, 17 June 2019 - 01:55 PM.

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#11 t_image

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Posted 17 June 2019 - 09:38 PM

Yeah Daniel,the IF IT AIN'T BROKE, YOU CAN'T FIX IT! is the worst.

I am actually afraid of something a bit worse:

thinking it is fixed, but then it comes back at the worst time because the problem was never solved!

 

So my diagnostic course will continue towards finding the problem more than trying to treat the symptoms, I wish more medical doctors had this approach......

 

My first goal is to find predictability in the malfunction.

Second is to slowly implement fix attempts one at a time, trying to see if the problem will come back....

I could try effecting every solve immediately but that won't tell me if something fixed it and if it could return in the future.....

 

Well no demons found so far today,

but I did achieve one important data point!!!!

 

If while slewing the mount the hand controller connector is pulled out from the mount, the mount will continue to slew on its own.
This is very similar to my symptom

as I believe every demon episode involved the mount continuing in the initial slew directions commanded.

Never do I recall it starting on its own, less sure but pretty convinced that it hasn't changed directions on its own will....

However: when the HC is unplugged, the HC display shuts off. This is not similar to my symptom.

 

But at least it is a tell of the hardware/software structure that an initial command to the motor control board to slew,

means it will continue even if there isn't continual commands to continue.

 

This allows the potential for a faulty comm wire to intermittently fail and end comm signals and the demon 'takes over'.......

While the other connected wires to the HC keep the display lit.......

Obvious enough when disconnected, the HC doesn't report any errors once plugged immediately back in while the mount has been continuing to slew on its own......

 

I wouldn't recommend doing this (pulling controller/replacing while running) but I don't have much to loose with an unreliable mount at the moment.

 

The AVX in my case is not overkill.

Yep Greg, just in case to clarify, I was only stating that AVX was overkill for a particular use case for me, anticipating others just recommend I use my AVX instead of hassling with this wimpy mount......

Also, it is nice sometimes to diversify tasks of my mounts!



#12 chicagorandy

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Posted 17 June 2019 - 11:01 PM

Sure seems to be pointing in the direction of a wonky connection of a wire or two in the HC plug socket in the mount?



#13 t_image

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Posted 01 July 2019 - 02:51 AM

FWIW,

update:

demon returned tonight while out (been quiet for a while).....

Now I'm sure direction isn't an issue (acts up if going Left or Right) now that I am noticing and remembering.....

 

Also, I tried plugging HC in both the HC port and AUX ports and demon caused issues in both situations.

So ruled out is specific interface port on the mount......

 

A few times I was able to recover w/o shutoff by pressing back after HC read "error 16, press back".......

Again my use case is fast slewing, especially in diagonal (two direction keys simultaneously) while chasing planes or satellites.....

I'm down to my last function NEX HC, so I may switch out the curly wire with another HC controller next.

Also I was using the 5A AC power supply this time, so no chance power was issue (also source battery was powering other items that would have protested if current was low)......


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#14 Volrue

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Posted 01 July 2019 - 06:31 PM

I have a Celestron CG-5 that had runaway slews. I updated the firmware on the moter controls which fixed the problem for me. I had a lot of trouble updating and getting errors, but once i found a computer that had the correct plug-in and was able to remove the usb adapter, it downloaded first try.

 

good luck, and clear skies,

Clay


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#15 skaiser

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Posted 06 July 2019 - 05:24 PM

So, if you have a PC.

 Can you try using CPWI to control your scope without the Hand Control being connected.?



#16 TelescopeGreg

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Posted 14 July 2019 - 05:19 PM

I should probably update my earlier comments about my slewing issues.  As I noted elsewhere, apparently the issue was caused by a "collision" between PHD2 actively guiding the mount, with me commanding a slew via the hand controller.  If I stop the guiding first, the slew seems to complete properly. 

 

That the mount was "fine" when I first got it was therefore because I wasn't guiding at the time...




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