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Problem with Meade 12 inch secondary - it's really loose!

Meade optics SCT
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#1 drmedjools

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Posted 19 April 2019 - 11:10 AM

Hello Helpful Folks..

 

We are trying to use an older Meade 12 inch SCT in my classes at Irvine Valley College in California.  Last night we noticed why the collimation is so flakey as we move the scope around on JMI tripod roller stand:  the secondary can move 3-4 mm when we pull on it.  Of course, it can also rotate.  What happened to this 'scope before I started using it?

 

Anyway, I'd like to see if we can try to fix it before we have to engage Meade to fully repair it.  Any ideas?  I know there are lots of discussions about concerning the secondary rotating against the fixed corrector.  This has gone beyond that where the secondary can move 3-4 mm 'radially' away from the corrector.  We tried to 'screw it back' by rotating the secondary but both the inside and the ourside (woth the collimating screws) move at the same time.  Is there anything in the collimating screws that repair this?  I'm looking for some kind of screw inside the secondary that can be torqued to pull both sides of the secondary mount back together.

 

My guess at this point is that we have to remove the entire corrector plate assembly away from the 'scope and then hand tighten boths sides of the corrector.  If so, does anyone have a good writeup of how to remove the corrector?  We tried unsuccessfully once to do this to clean the corrector of some liquid stains to no avail.

 

Anyway, any help to get this 3-4 year Meade back to work for our students would be appreciated. 

 

Dr Medjools



#2 gnowellsct

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Posted 19 April 2019 - 03:18 PM

THE BASIC IDEA   

 

Sounds like you will need to check the secondary assembly.  In the usual case a metal disk with screws that do the adjusting.  The mirror is secured to the metal disk.  If the glue is going then it will have to be re-glued.

 

I know several people who run outreach observatories and they all say:  "We get a lot of calls from people who want to donate Meades, and all of them are broken."




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