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Mirror lock adjustment

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#1 Martin Lyons

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Posted 16 May 2010 - 11:37 AM

Can anyone point me to instructions on how to adjust the mirror lock on my 16"LX200GPS ?
The mirror lock reaches the mechanical stop and the mirror can still move quite easily with the focus mechanism.

I need it to lock a little tighter.

Martin

#2 SanDiegoPaul

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Posted 16 May 2010 - 12:05 PM

Sounds like your lock system is broken.

#3 Martin Lyons

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Posted 16 May 2010 - 03:02 PM

Sounds like your lock system is broken.

Nah, don't think it's broken as such, just in need of adjustment.
I vaguely remember an article a while ago that showed how to adjust it if it reached the mechanical stop on the ring gear before it tightened sufficiently.

I'm hoping someone can point me to that article or similar info.

#4 iriise

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Posted 16 May 2010 - 03:39 PM

Maybe this is what you read?
http://www.petersone...rrorLockFix.htm

#5 GaryHeath

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Posted 16 May 2010 - 04:58 PM

As above.

FWIW: Here is what the internals of the 16" look like ....
These are some pictures I took when I disassembled mine (within about 3 days after it was delivered from Anacortes) to re-drill the holes for a better finder location.
I'm not sure what Meade was thinking of with the stock finder bracket location, as it really caused problems once I bolted up the Losmandy top DM system.

Anyway ..... the pic's are of the 16's primary assembly, focuser knob, mirror lock knob, primary mirror locking collet, springs/pucks, and etc., and are pretty much the same for all sizes (with certain exceptions like the mirror "tuning fork" orientation guide., spring placement, and etc.).

The large gear is the collet gear, the fork at about 1:00 is the orientation fork and focuser pin is at about 2:30.

Best regards,

Gary

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#6 GaryHeath

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Posted 16 May 2010 - 04:59 PM

2 - Here you can see the brass collet ring inside the collet housing.

This works much the same as a brass ring in a drawtube, but is closed by the funnel shape of the inside of the collet housing so when this housing is threaded farther on it's base, the funnel shape causes the brass ring to close around the back end of the baffle tube and lock the mirror.

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#7 GaryHeath

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Posted 16 May 2010 - 05:00 PM

3-

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#8 GaryHeath

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Posted 16 May 2010 - 05:01 PM

The knob on the left is the mirror lock.
It engages the collet gear teeth, so when the lock knob is turned CCW that action turns the collet gear CW, which tightens up the collet housing causing the internal funnel to close the brass ring around the baffle tube.

The knob on the right is the focus assembly.
The hole in the end of the threaded extending rod slips over the pin in the first photo, and by turning the knob CW the threaded portion is drawn back into the long focuser knob, moving the mirror rearwards, and vice versa to move the mirror forward.

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#9 Martin Lyons

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Posted 17 May 2010 - 12:53 AM

Thanks ever so much Iver and Gary, you've been a great help.

Iver, yes, that was the article - thanks.

Gary, great pictures that are very helpful - thanks for documenting so clearly.

I'm going to adjust mine as described in the Petersons Engineering article.

Thanks again folks

#10 PatHolland

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Posted 17 May 2010 - 10:11 AM

Hello! This is a fascinating thread. Are you guys saying that when the mirror lock is enabled that the course focuser should NOT turn? If this is the case, then I need to adjust both of my LX200 scopes.

#11 GaryHeath

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Posted 17 May 2010 - 01:23 PM

Yeah ...... once you lock the mirror you should never turn the focuser knob until you unlock the mirror.

If you do turn/force the focuser with the lock on, you will cause damage that requires you to readjust the lock.
As with any collet ..... this can only be done a number times before it's parts become too worn to allow the adjustment to work anymore, and then the lock becomes useless.

Best regards,

Gary

#12 Martin Lyons

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Posted 17 May 2010 - 01:24 PM

Well, I took the air filter off and also removed the mirror lock knob.
I tried to turn the mirror locking geared ring (the large one)as tight as I could with my fingers to see where the mechanical stop (toothless part of gear) stopped in relation to where it stops when using the mirror lock knob.

There is a mere 2 teeth difference in travel.
I tightened it as tight as I could with my fingers.

The course focus knob still moves the mirror with ease ?????

I thought the mirror lock would make using the course focus difficult or even impossible.
I thought that the mirror lock function literally clamped the mirror carrying tube to the baffle tube.

Something doesn't sound right here or am I mistaken?????

Dr Clay, you out there?

#13 Martin Lyons

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Posted 17 May 2010 - 01:25 PM

Sounds like your lock system is broken.

You may have a point :bawling:
I'm starting to think so too :foreheadslap: :help:

#14 NeoDinian

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Posted 17 May 2010 - 06:11 PM

The focus KNOB will still turn. But you are NOT moving the mirror. You are BENDING the focus rod! We're not saying that locking the mirror will STOP the knob from turning... We're saying that once the mirror is locked, you should NOT turn the focus knob!


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