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GoTo Failure on Celestron Nexstar 6SE

beginner Celestron
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#1 OKBioCat

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Posted Yesterday, 12:32 AM

This is my first post to Cloudy Nights. I apologize if this has been covered in another topic, but I had an issue tonight with the GoTo on my 6SE.  I finally got a good Auto 2 star alignment and had just pointed it at the moon for some simple lunar viewing.  It worked perfectly.  In fact this was probably the best alignment I have done to date as I have only owned the scope for 2 months and am still learning.  Unfortunately a small thin cloud drifted in front of the moon so the kids and I decided to wait for about 10 minutes for the cloud to drift by.  After the cloud moved on, I redid the Goto for the moon to recenter it in the eyepiece and the scope slewed to straight up.  We never turned the scope off or did anything to disturb it.  I am powering the scope with a Talentcell 12V 3amp supply because I have read on here that using onboard AA batteries can lead to performance issues.  The power supply was freshly charged and had only powered the scope for about 20 minutes total when this issue occurred so I am fairly certain that enough power was being supplied to the scope.  (The LED lights on the power supply showed full charge)

I remember reading about similar issues on Cloudy Nights but I can't seem to find the posts now.

I am getting quite frustrated with this scope.  I used to have an 8" Intelliscope dob but never used it because it was hard for me to transport.  I bought the 6SE to be more portable and have the computerized goto to help me find more items such as Messier objects etc.  So far, I am struggling to view the moon and planets using the Goto system.  I know from reading on here that I have a lot of things to do to improve my alignment skills so I don't mean to complain about that.  It was just particularly frustrating to get one right and have it blown like that.

Sorry for the rant and thanks for all of the help this community gives to newbies in this hobby!


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#2 sg6

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Posted Yesterday, 02:02 AM

Cannot read anything wrong, well really wrong.

Does half read of low power - would suggest that you dig into the menu and reduce the Max Slew Rate to 6 or 7.

People leave them at full and full draws a lot from the battery, just thinking it may have been fully charged but was unable to supply the required current momentarily and that has caused the scope to lose it's marbles.

 

The other is likely not applicable but you had done a Goto the Moon. Then left it and and asked for a second Goto the Moon. Motors should have simply done no real action, slight twitch maybe, then said Done it. But makes me wonder if being on the target and being asked to goto the same target causes a problem. As said shouldn't and never heard of it, but I come from Software Test and it is something I would note and check. Force of habit, especially in safety critical software.

 

Actually the moon should have still been in view, if it was well out then maybe the alignment wasn't as good as thought. The idea is you goto the target and then it tracks - lunar rate is not that much different, but a 6SE has a long focal length - have you a wide eyepiece?

 

My guess is the battery was unable to supply a peak demand at full slew probably in current and that the electronics just lost something. So try reducing the Max Slew Rate, also makes it a bit quieter.



#3 OKBioCat

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Posted Yesterday, 11:05 AM

Thanks for the tip on the slew speed.  I will look into that.  I want to review some other settings after reading pollywog's posts on aligning the 8SE so I have some checking to do.  I really appreciate the help!



#4 BPoletti

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Posted Yesterday, 11:24 AM

If the tube is not balanced correctly in the mount and the clutch is a bit loose, the scope may end up being "back heavy" and tilt up.  It can be a problem if the tube is centered in the mount.  Best to test the balance point, market it on a piece of masking tape on the side of the tube (visible next to the mount), and center the mark in the mount.  It may be quite far back on the tube.  

 

If the tube moves easily in the mount in the alt range, the clutch may be tightening.  It's an easy process.  Do a search on Nexstar SE clutch adjustment for details.     



#5 Terrybythe sea

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Posted Yesterday, 02:02 PM

My guess is the battery was unable to supply a peak demand at full slew probably in current and that the electronics just lost something. So try reducing the Max Slew Rate, also makes it a bit quieter.

Unless I'm missing something, I don't think a max slew rate can be set for SE mounts. You can choose the rate for manual slews, but GoTo's seem to have a mind of their own, and often (always?) use speed 9.



#6 Newbutnotreallynew

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Posted Yesterday, 05:22 PM

Unless I'm missing something, I don't think a max slew rate can be set for SE mounts. You can choose the rate for manual slews, but GoTo's seem to have a mind of their own, and often (always?) use speed 9.

You can change the slew speed on the SE mounts I've seen it mentioned here a lot. 



#7 lkannard

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Posted Yesterday, 10:03 PM

I think your TalentCell is under powered. I use a 12 Volt 6 Amp and never have an issue with alignment or tracking.

#8 OKBioCat

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Posted Yesterday, 11:28 PM

UPDATE:  Thanks to all who replied to this post.  I think having AA batteries installed along with my Talentcell was my core issue.  Last night when I was having the power problems, I had the Talentcell hooked up to the mount, but I also had AA batteries installed as "backup"  Today during the day I improved the alignment on my red dot finder and checked the settings on my Nexstar+ hand control.  The slew speeds in both directions were already set to 1-6 so I didn't change anything there. I did change my alt setting to positive from negative based on Pollywog's post about aligning his 8SE.  Then I removed the AA batteries from the mount.  I did not recharge my Talentcell.

Tonight I went out and set up the scope. Everything went very well.  I aligned it in about 10 minutes and then pointed it at various stars all around the sky.  Each star was found and located within the field of view of my 32mm eyepiece, even the ones farthest from my alignment stars (Altair and Antares).  I can say with confidence that any Goto issues tonight were due to my technique rather than any technical problems with the scope. I stayed out for 2 hours and slewed the scope quite a bit all over the sky.  At no time did there appear to be any slowing of the slew speed or any tracking issues.  I centered on Jupiter, took a break for about 10 minutes and came back and it was pretty much just where I left it in the FOV.

I think the problem was that the mount was using the AA batteries as the "primary" power source even though the Talentcell was hooked up.  I don't know if that is technically correct but that seems to be the main thing I changed that had an effect on the Goto performance.



#9 Michael_Swanson

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Posted Today, 12:43 AM

You can change the slew speed on the SE mounts I've seen it mentioned here a lot. 

"Custom Rate 9" is available on the 4SE/5SE mount but not the 6SE/8SE mount.  Celestron neglected to add the feature to the MC firmware for the 6SE/8SE.

 

Best regards,
Mike Swanson
https://www.NexStarSite.com



#10 Newbutnotreallynew

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Posted Today, 04:20 AM

"Custom Rate 9" is available on the 4SE/5SE mount but not the 6SE/8SE mount.  Celestron neglected to add the feature to the MC firmware for the 6SE/8SE.

 

Best regards,
Mike Swanson
https://www.NexStarSite.com

 

Oh that's very informative thank you Mike. 




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