Meade Help Required

[thunderchildobs]

I have A 14" Meade ACF LX200 OTA with some series focusing problems.

I had focusing issues for some time. I did the full wind out and wind in thing multiple times with the focuser, to spread out the lubricant.

Now I cannot achieve anything close to focus. I can see a large out of focus star, but turning the focus knob now seems to make no difference. I have turned the focuser from all in to all out.

I can feel tension and weight when I turn the focuser.

Any suggestions

Brendan

[Merlin66]

Hmmmmm....
That's not normal.
Check the position of the mirror on the baffle, look into the tube from the front, and then move the focuser knob to the max either way - see if the mirror actually moved up and down the baffle.

[beren]

Sorry for asking but is the mirror lock fully disengaged ? The old Meade Mapug pages might offer some ideas, predates the ACF range but the mechanics would roughly be the same ......

http://www.skymtn.com/mapug-astronomy/MAPUG/ImgShift.htm

[Ukastronomer]

I agree my ED Celestron has mirror lock, has it been focused without dis engaging the locks at any time

[thunderchildobs]

The mirror lock is fully disengaged.

[thunderchildobs]

I could not see the mirror moving by looking down the tube from the front.
However, looking up tube, I can see the image on the secondary changing.

[thunderchildobs]

More information.

When looking up the tube from the back with nothing in the visual back I can see a image in the secondary.

Image1 shows what I can see when the focuser has been fully turned anti-clockwise.
Image2 what is visible when the focuser is fully turned clockwise.

The tube is horizontal.

Image2 clear shows a problem.

Is the problem with the focuser, mirror tilt, collimation?

Any ideas would be helpful.

Thanks

Brendan

[beren]

http://starlightinstruments.com/store/image/data/PDF/Meade%20MicroFocuser.pdf

Above is a a link to the feathertouch microfocuser installation for the Meade 14” , if your up to it maybe following the instructions to remove the original focuser knob might help diagnose a problem.

[casstony]

It's possible that the main mirror has come loose from the tube on which it is mounted.

[Merlin66]

If you don't see the main mirror move when focusing, it could be the focuser rod has dislodged from the locating pin on the rear of the mirror.
I never experienced that in almost twenty years of SCT use, but anything is possible.

[Ukastronomer]

Or at some stage it has been focussed with the clamps "clamped" causing a problem

[Merlin66]

My experience is with the Classic Lx200...
Found a couple of links which may be of interest...
https://www.cloudynights.com/topic/350473-lx200-mirror-lock/

https://astromart.com/reviews/telescopes/show/whats-inside-a-meade-lx200-14-sct

Hope you resolve the issue.
[Edit] I'm not suggesting at this stage you need to completely strip the Meade....just some ideas as to how the focuser works and may be rectified if needed.

[thunderchildobs]

How much movement should I see? There is some movement as shown in the images in the post above. I couldn't tell if the movement was in /out or if the focuser is only pushing on one side of the mirror.



Not they I can remember. The scope is only used for imaging and I use a Meade zero shift focuser.

Brendan

[thunderchildobs]

Just in case, does anyone know someone who can service Meades (ideally in Brisbane) ?

Brendan

[Merlin66]

Brendan,
The movement of the mirror along the baffle tube should be enough to be noticed...about 40mm??

[AstroJunk]

Hi Brendan,

I stripped mine down completely for a clean and re-grease last year and they are remarkably simple inside. I'll see if I can dig out some photos later on to help.

[AstroJunk]

Everything you need to know about the internals of your OTA :)

[PeterM]

Here is a video I found of removing a Meade focuser to replace with a Peterson. I guess the innards are the same for the 14inch. Kind of shows whats inside if that helps. https://www.google.com.au/search?source=hp&ei=QOxHXPn2KJWk-Qbu7K6YAg&q=lx200+focuser+removal&btnK=Google+Search&oq=lx200+focuser+removal&gs_l=psy-ab.3...1738.19217..19554...3.0..0.3 36.6364.0j3j15j7......0....1..gws-wiz.....0..0i131j0j0i3j0i22i30j0i22 i10i30j33i160j33i21.pQTMcZt7fmg#btn K=Google%20Search&kpvalbx=1


This may also be of use as it relates to a 14inch
http://www.centaurus-a.nl/home/meade-14-focus-mechanism-repair

[thunderchildobs]

When I remove the focuser, which is the best / safest / easiest way. Can I remove the focuser while the scope is still on the mount, (keeping the tube horizontal) or do I need to dismount the tube from the mount?

Thanks Brendan

[Merlin66]

Brendan,
As long as the tube is horizontal or slightly inclined upwards there's little chance of the mirror sliding on the baffle.

[AstroJunk]

Leave it on the mount and horizontal, erring on leaning back toward the focusser. As soon as you have removed the 3 bolts, you can move the main mirror by pulling the mechanism back and forth. Just slip it sideways and the focus mechanism will come off the pin and can be removed.

Just make sure that the primary mirror isn't facing downwards when you finally set it free!

[thunderchildobs]

Another question. Does the mirror lock need to be engaged or disengaged when removing the focuser?

[AstroJunk]

Either. BTW Having the mirror lock unit in position actually prevents the mirror slipping off the shaft if you have the tube pointing downwards and it is unlocked.

I prefer it unlocked so I can get a feel for how freely the mirror is moving.

[thunderchildobs]

I have removed the focuser to see what it looks like.
The focuser and the bar it attaches looks ok, straight and everything seems firm and there is nothing rattling in the tube. (1st and 2nd images)

What I did notice when a reinstalled the focuser for the first time, the focus lock jammed and turning the focuser was very stiff.

I removed the focuser and tried again. As I was tightening the focuser screws , I turned the focuser lock and could see the focus knob turning!! It seems like some part of the focuser is touching the focus lock tooth plate.
Have I incorrectly reinstalled the focuser? At this time I haven't removed the focuser lock.

Looking through scope it seems that the primary mirror is not square (3rd image)

Looking down the tube there seems to 4 screws (4th and 5th image) that come from tube and I cannot tell what they do. They appear to be touching mirror or at least the mirror cell. What is the purpose of these screws?

Thanks

[Merlin66]

Ahhhh
You may have found the problem/ issue!
Those two screws you show in photo#4 should NOT be there!!
It looks like the screws, used to attach a finder etc are toooooo long and probably interfere with the mirror travel.
They should be unscrewed to at least stop any interference with the mirror.

[casstony]

Was the tube originally in a fork? Looks like a deforked model and the screws used to fill the holes are too long.

[thunderchildobs]

Thanks. Those screws are definitely in the position where the forks attach to the tube. They have always been there since I bought the scope new in 2010!! The focuser had always been easier to turn in some places and harder in others. I always thought it was just a focuser thing. The scope has always been a imaging scope and I used a meade zero shift focuser. No need to touch the focuser knob once set.

I removed the screws and guess what, the focuser is now nice and smooth.
I can now also see a noticeable movement in the mirror when the focuser is turned fully in and out.

I can now get to focus. This has solved my original problem.

However, I now have a collimation problem. I am going to start a new thread for this.

Thanks to everyone who offered help.

Brendan

[Greg Bock]

Great thread guys, ..co-operative, helpful, and informative.
Now i must have a look down inside my 14" tube to see what's there..just out of curiosity.