LX200GPS Secondary Mount Loose :: RESOLVED

[knobby4444]

Hello All,

I purchased a used Meade LX200GPS last year (used, purchased new in 2006) and am slowly trying to learn how to use it and get it dialed in.  I am new to astronomy but I did help a friend figure out how to use a similar Meade telescope in the past.  It seemed to be fairly well collimated when I first checked it.  Recently we have been looking at Saturn and Jupiter and noticed it seems a little blurry.  I found a document online that talks about fine collimation and decided to try.  When I did I noticed the secondary mirror is not well mounted in the correcting lens.  The entire assembly will rotate and even wiggle some.  I have the 6 screw secondary.  I tried tightening the 3 outer screws a bit and that did not seem to help.  They seem tight enough already and I don't want to tighten them anymore without some advice.  Has anyone here had the secondary assembly get loose and if so, how was it fixed?

Thanks,

Jake in Austin, Texas

Edited August 31, 2020 by knobby4444

[AstroFin]

Hi Jake!

I had a similar problem with my Celestron C8. The whole secondary assembly was loose. The problem was solved by replacing the original paper-like gasget (located between the corrector plate and the secondary mirror assembly) with a new improved one from Starizona. Although I can’t be 100% sure, I don’t think that the Meade SCT design is that much different from Celestron, so perhaps this might work for you too. The fix does require removing the corrector plate and the secondary mirror. I did the repair myself and did not find it too difficult.

Here’s the gasget I used. Not sure if it is Meade-compatible, though.

https://starizona.com/store/manufacturers/starizona/hyperstar-conversion-kit-c8-gasket

I hope this helps, clear skies!

Tomi

[knobby4444]

I just created a video and it does sound like the same issue  you had Tomi.  I am nervous about removed the correcting plate, but it does appear to be 7 bolts to remove and it would come off.  Thanks for the advice!

https://jakethesnake.net/Telescope-Issue/GOPR5573-1.MP4

Are there any good threads on here about removing the correcting plate on an 8" LX200GPS that anyone can point me to?  I've search some but haven't found anything yet.

[knobby4444]

Ends up this is a very easy fix, thankfully!  The inner and outer parts of the secondary mount are threaded together.  Remove the 6 screws holding the 8" ring that secures the correcting lens, remove the ring, and then pull the correcting lens out by the secondary mount.  Finally, hold the inner and outer parts of the secondary mount and tighten them together.  Put it all back together.  I have read that the orientation of the mirror is important, and I think I have it close to the original orientation.  Will be testing it out tonight.