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Celestron AVX Motor, RA

Celestron Mount
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12 replies to this topic

#1 b.bill.p

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Posted 13 September 2021 - 07:31 PM

For the curious here are two photos of the Celestron AVX RA motor gears. The DEC motor should be exactly the same.   After 5 years I expected a disaster but actually its very clean with no visible signs of wear.  I’ll make a thin copper shim to snug up the main shaft lateral play then apply a little grease and put it back together.   All I found was that the two screws holding the gear box to the motor body were very loose and the main shaft brass bearing could be replaced with a caged roller bearing in the future.

 

5B67203C-0CA5-485D-A41F-E6CCE32A65CD.jpeg 2078E4C8-FF10-41A7-B4D1-AC69439B9928.jpeg


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#2 kmholtz76

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Posted 14 September 2021 - 06:57 PM

That right there is where a good chunk of the AVX DEC backlash is....and the only one of the 3 (here, spur gears, and worm) which isn't adjustable.

I've often wondered if these gears could be replaced with higher quality ones to help reduce the play.

Kevin
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#3 Wardnb

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Posted 15 September 2021 - 08:26 PM

You can adjust it a little. Loosen the two screws and pry the plate a little to get it loose. Mine were glued down to the motor. There is enough play in the screw holes to adjust the mesh from the motor to the first gear. The rest aren't adjustable, but that adjustment did make a difference in the final backlash I was getting.

#4 kmholtz76

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Posted 15 September 2021 - 08:44 PM

Interesting....Thanks

#5 South Texas Gazer

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Posted 15 September 2021 - 11:05 PM

Has anyone run into this issue?

 

I received the AVX Sept. 2nd and at first, it worked great. 2 weeks later and this is happening.

 

latest firmware
Album: AVX Issues
4 images
0 comments

 

Obviously a defect, but interested to see if I'm the only one that it's happened to.



#6 Old Man

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Posted 16 September 2021 - 12:51 AM

I have had my AVX for 4 years and never had a problem that was not user induced. Try a factory reset and start from scratch, ditch the wifi and use only the hand control,

 maybe your wifi is picking up some interference. Worth eliminating that to see. Make sure all your time, date, and location is correct.

 

Just a guess, but maybe it will be OK. Then try with the wifi and if it goes crazy again you will have found the problem.

 

  Good Luck, and let everyone know the outcome.


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#7 South Texas Gazer

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Posted 16 September 2021 - 11:09 AM

Hi Old Man,

 

Thank you for the response. I'm actually hoping it's user error. Over the past few days I've tried everything you mentioned above especially removing the WIFI adapter. I suspected there might be something interfering with it but it proved not the case. I even turned on the mount without anything plugged into it including the hand controller and StarSense camera. It again started on it's journey without anything connected. I also did the fully HC reset and flashed the firmware multiple times. Looking at the HC versions info, they all appear to be correct as well. I read in another post about the chance of the NextStar mount driver accidentally being installed. That isn't the case as it shows the proper model as "advancedVX" so that is also good. I even used a different power source thinking that might have something to do with it. But it didn't.

 

I also found another post that someone described the exact issue I am having, but they didn't post any kind of fix. Just that their RA was going crazy.

 

I called Celestron last night and they were even perplexed as to why it was happening. I sent them the videos I posted above so they can see what I'm seeing. Hopefully I'll hear back from them soon. I'm still in the window of return to Amazon so I don't feel stuck with it or the need to send it to Celestron for repair just yet. I just want to see if I can figure it out on my own before doing so.

 

If anyone has any other suggestions, I'd be happy to try them out. If I can't figure it out in the next couple of days, I'll more than likely send it back this Saturday for replacement.



#8 Old Man

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Posted 16 September 2021 - 03:41 PM

One other thing. Have you hot plugged or unplugged anything into the AVX or plugged any into the wrong socket? Never hot plug or unplug anything into the mount with power on, sometimes all it takes is just a momentary short to fry something and plugging things into the wrong socket will def. fry components. All the Aux sockets are wired the same but guiding port and HC are not, Dec. has its own cable.

 

  Good Luck


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#9 b.bill.p

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Posted 17 September 2021 - 10:28 AM

1) I think the motor gears looked very quality to me and there is zero backlash in my motor gears.  Before assembling the gears received a small drop of SUPERLUBE .

 

2) That runaway problem could be a bad connection to the Motor Optical Position sensors on the defective axis. Remove the cables and re-attach better yet SWAP the RA and DEC motors to see if the problem follows the motor/Optical senser..  I would suspect a bad connection at one end of the cable but hopefully not a bad senser assembly.  Also check the electronics board maybe some critter built a nest inside.    I had to return a NEW Losmandy gm811g because it did exactly what you are describing plus it was a piece of junk with egg shaped gears and could not track so don’t upgrade to that product.  

 

Celestron mounts are Gaurrenteed for 2 years but after sending my new CGX in for repairs this year the turnaround time was 60 days, terrible but now my CGX is rock solid.   My AVX is too old so yesterday I cleaned and replaced the old black grease with a light coat of SUPERLUB and the action feels a lot smoother.     

 

Dang this FONT size is so small I can barely read my post so excuse any errors … 


Edited by b.bill.p, 17 September 2021 - 10:37 AM.

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#10 South Texas Gazer

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Posted 18 September 2021 - 02:47 PM

One other thing. Have you hot plugged or unplugged anything into the AVX or plugged any into the wrong socket? Never hot plug or unplug anything into the mount with power on, sometimes all it takes is just a momentary short to fry something and plugging things into the wrong socket will def. fry components. All the Aux sockets are wired the same but guiding port and HC are not, Dec. has its own cable.

 

  Good Luck

Hi,

 

I've been very careful not to do that. I did get a response from Celestron about possible causes. Here's what they sent:
 

Because it is happening with both HC and SkyPortal app It could be the motor but he is only doing it with the one axis so I cant tell if both are doing it.
If it is just the one axis then I would say motor with possibility being the Motor control board. If it is both axis then definitely motor control board.

 

The unit is new and the customers return window is still available, he is able to use the Amazon replacement route if he would like, however the unit can come in for repairs, and it would be a simple Motor Control swap. Especially since he says he was twisting the power port it could have bent the connector causing it to short?
Either way, our recommendation is for the item to come in for repair.

 

I also asked about the motor since the mount slewed and stopped after hitting the tripod but kept running. I included this shot of the scenario.

 

motor damage possibility

 

Here's there response:

 

This action can damage more than he motor, it can damage the worm and main gear.

So I ended up opening the compartment for the power and aux ports and loosened the board so I could see if the power wires had twisted when removing the power cable. They had, and also almost unplugged the power from the board. I untwisted the wires and pushed the connector back on, closed it up and tried it out last night. The scope didn't slew on it's own anymore! BUT, the RA tracking was erratic even after aligning using StarSense. I figured it might have been a bad alignment, so I retried aligning probably 5 more times, each with the same result. I'm leaning on the second response they sent and deduced that the work gear may have been damaged.

 

Final decision was to return it while I still can. Now comes the process of deciding if I want to re-order the same mount or maybe upgrade to the next level and get a CGEM II EQ Mount and Tripod. Still thinking that one over.


Edited by South Texas Gazer, 18 September 2021 - 04:58 PM.


#11 South Texas Gazer

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Posted 18 September 2021 - 02:50 PM

1) I think the motor gears looked very quality to me and there is zero backlash in my motor gears.  Before assembling the gears received a small drop of SUPERLUBE .

 

2) That runaway problem could be a bad connection to the Motor Optical Position sensors on the defective axis. Remove the cables and re-attach better yet SWAP the RA and DEC motors to see if the problem follows the motor/Optical senser..  I would suspect a bad connection at one end of the cable but hopefully not a bad senser assembly.  Also check the electronics board maybe some critter built a nest inside.    I had to return a NEW Losmandy gm811g because it did exactly what you are describing plus it was a piece of junk with egg shaped gears and could not track so don’t upgrade to that product.  

 

Celestron mounts are Gaurrenteed for 2 years but after sending my new CGX in for repairs this year the turnaround time was 60 days, terrible but now my CGX is rock solid.   My AVX is too old so yesterday I cleaned and replaced the old black grease with a light coat of SUPERLUB and the action feels a lot smoother.     

 

Dang this FONT size is so small I can barely read my post so excuse any errors … 

Hi Bill,

 

You posting that it took forever to get it returned prompted me to just send the mount back and get another. I'm thinking about the CGEM II EQ Mount and Tripod but haven't looked into it enough to gauge whether or not it's worth the extra money.
 


Edited by South Texas Gazer, 18 September 2021 - 02:51 PM.


#12 b.bill.p

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Posted 18 September 2021 - 10:22 PM

I went for the CGM because its really a life long investment.   Don’t fret over a bad mount, I bought a new Losmandy GM811g last November and it never worked correctly, my images had a lot of jitter in 15 second exposures and once in a while the mount would slew off pretty crazy like.  The gears were oval shaped, that is they only turned freely for 180 degrees then jammed tight, I returned it for credit but the return took forever.   This new CGM had RA trouble so Celestron sent a new one to me that is rock solid and tracks near perfect .   I’m keeping my old AVX for club outreach events, adjusted it yesterday and was able to image 90 seconds with very very slight slew error so with PHD2 guiding it will work fine …. bite the bullet, return the faulty mount and get a CGM, they are plug n play like the AVX, same PC software setup.    

 

PS buy the mount from Celestron direct, I bought mine from telescopes.com which is the camera store in Thousand Oaks, California.    


Edited by b.bill.p, 18 September 2021 - 10:24 PM.


#13 b.bill.p

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Posted 20 September 2021 - 05:15 PM

Correction, I upgraded to a CGX not CGM 




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