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Celestron Focus Motor, Calibration stalling / not working (alternative motor tested, same result)

Sky-Watcher AZ-EQ6 PRO Equipment Focuser Troubleshooting Help Needed
15 replies•311 views
muehae avatar
muehae avatar
Hi,

We are using astronomy gear as follows:

Celestron 9.25 edge hd telescope
Skywather AZ-EQ6 Pro
Celestron FR 0.7
ZWO 2600 Cmos camera
Win 10 64 bit (Thinkpad P52)
and lately a new Celestron Focus Motor. We installed hardware as depicted in the manual and double checked via some internet research. We neetly fixed motor to the telescope (all screws, including allan screw with blue loctite, motor). Connection via USB 2.0 cable seems to be working (motor is turning on command). But Problem is, calibration does not finish and is stalling after 30% progress. Same with ascom or sgp.

Due to troubleshooting efforts we installed an alternative brand new focus motor, a second brand new usb cable. Installed driver again and utility software again and initiated celestron utility software and hit connect.

Strangely it did not recognized the alternative motor and resumed to the initially stalled calibration process at 30%. I am pretty sure, we could exclude hardware as source of the problem. But not sure.

How would you force a recalibration process? We have already wrote to celestron, reply pending...

I do not know what to do next! Please give us a hand! Thank you very much.

Best regards
David Redwine avatar
David Redwine avatar
Take the focus motor off and turn the focus fully in and out by hand.  If the shaft "wobbles" as you turn it it is off-center or bent and it will stall the focus motor.  I remember a forum post on CN that had a process for making the motor work with an off-center focus shaft, but I didn't save the URL.

My focus jams, but only at "terrestrial" distances.  I was able to wiggle the motor enough to get it unstuck during calibration.  I don't plan on needing to focus at 75m so it doesn't affect operation.  If the motor binds near infinite focus you have a problem.

CS
Helpful
muehae avatar
muehae avatar
David Redwine:
Take the focus motor off and turn the focus fully in and out by hand.  If the shaft "wobbles" as you turn it it is off-center or bent and it will stall the focus motor.  I remember a forum post on CN that had a process for making the motor work with an off-center focus shaft, but I didn't save the URL.

My focus jams, but only at "terrestrial" distances.  I was able to wiggle the motor enough to get it unstuck during calibration.  I don't plan on needing to focus at 75m so it doesn't affect operation.  If the motor binds near infinite focus you have a problem.

CS

Thank you. This probably cuts the salami. Focuser shaft seems to be bent a little. Hence Focus motor jams basically at every position (it moved in about 2 - 3 revolutions once  ...)

What would you recommend.  Is this a spare part? Philips srews are pretty worn out too.
David Redwine avatar
David Redwine avatar
Contact Celestron and tell them what you found.  I think the focus shaft is replaceable.
Well Written
muehae avatar
muehae avatar
already did. Furthermore find this:

https://www.celestron.com/products/focuser-retrofit-kit-for-rowe-ackermann-schmidt-astrograph-rasa-11

If standard focuser is available for RASA 11, maybe it is available for SCT 9.25. If "standard focuser" does extend to all telescopes. Maybe i can get lucky. thank you!
Rich Sky avatar
Rich Sky avatar
Do your calibration using your hand controller, and see if you get the same result.
Well Written
David Redwine avatar
David Redwine avatar
The RASA kit replaces the Featherlight focuser that is standard on the 11" RASA.  This would replace the focus shaft, but not the threaded rod that it connects to.  On my HD800 it is the threaded rod that has a slight bend to it.
Well Written Concise
muehae avatar
muehae avatar
@Rich Sky

Bearing Assembly seems to be bent. Hand Controller does not move focuser. I hope replacement bearing assembly will fit.

@David Redwinde
I hope our treaded rod is not bent that much. Bearing assembly definitely is.
Will report result after repair
muehae avatar
muehae avatar
Hi,

Replacement Kit of RASA 11 does not fit. My search neet to set to zero.

We need a bearing assembly replacement for a SCT C9.25 Edge HD and three Philips screews.

We would be very grateful for any help!

Thanks
J

Tim Hutchison avatar
Tim Hutchison avatar
I'm sure this isn't the kind of response that will be helpful to you, but I had the same issue with a brand new out of the box edge hd8, so I certainly didn't bend the focuser rod. I went back and forth with Celestron with replacement focusers (2) and was unsuccessful. In the end I purchased a Moonlite focuser and I ultimately think this is a much better solution. I can focus by hand and lock the mirror in place. Then all subsequent focusing is done with the Moonlite. I only redo the manual focus every month or so.

As I say, not sure if that is helpful but that is how I solved the same problem.

I hope you find a solution!
Tim
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muehae avatar
muehae avatar
Hi Tim,

same result with celestron. They won't even react to my tickets. When bearing assembly is bent, alternative motor simply does not work. I tried.

Have Celestron offered to replace bearing assembly or focuser shaft? Moonlite solution is - for now - a step to far. Which won did you buy?
Tim Hutchison avatar
Tim Hutchison avatar
Go here: http://focuser.com/products.php

Click on "CHL 2.5 inch Large Format Crawford EDGE Focuser". That's the one for the Edge HD scopes. I really like it and it has made a big difference in my images. The folks at Moonlite were really great to work with and very knowledgeable.

The ability to leave the mirror in place and just focus with the Crawford is probably how these scopes should have been designed in the first place. With the Celestron focus motor you have to leave the mirror unlocked which defeats the purpose of the mirror locks and leaves you dealing with mirror flop again! Honestly, I don't know what Celestron is thinking with this focus motor.

I don't mean to bash them or your chosen path towards a solution. Just some of my old frustration coming back out as I remembered dealing with this myself. Lol.

Like I say, I hope you find a solution to using it...

Best.
Tim
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muehae avatar
muehae avatar
very well put. Did not think about mirror lock! Think you are correct.

I am using a 9.25 Edge HD with 0.7 FR, Celestron OAG and so forth. Should be working. As it comes to planetary photography, our scope is outfitted with an baader 2" clicklock, an 2.0 Barlow and finally ZWO 2600. Not sure how to fit focuser between Barlow and Camera.

Thank you for your advice!

J
Tim Hutchison avatar
Tim Hutchison avatar
My email address is tim@the-hutchison-family.net.  If you'd like to send me an email, I will reply with the PDF manual from Moonlite that talks about backfocus spacing for this focuser.  I was/am using it for DSO photography, so I'm not using a barlow.  I don't know how much of your metal back focus that would take up so I can't give you exact numbers.  Plus, mine is an 8" and your using the 9.25", so the back focus is different.  However, I can tell you that I was able to perfectly dial mine in using a ZWO ASI1600M, EFW, and OAG without having to go to precise parts and purchase an adapter for both F/10 and F/7 shooting with the reducer.  The design of the focuser seemed to be specifically created to match the back focus of these scopes (as you would expect).

Let me know if you want to see that documentation.  I'm sure Moonlite would not mind my sharing it with you.

Happy to help in any way that I can.
Tim.
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muehae avatar
muehae avatar
Hi Tim,

you have email

Cheers
J
muehae avatar
muehae avatar
no reaction from celestron. Thanks to Tim Hutchinsons good advice and after some research und hopefully diligent consideration, we are going for a moonlite litecrawler.

Of course it is a little bit pricy, but raving reviews, combination of focuser and rotator are convincing!