TheSkySearchers

Hi,

In a hurry to get answer to my question, so went right ahead to Post.

My focuser in SkyWatcher MAK90 purchased in 2007(!) has fallen inside the tube.

Any suggestions how to get it repaired at home-sending to dealers seems costly and cumbersome.

Thanks all for any help.

Ananth
Top

Well that is a interesting problem.
Are you referring to the focuser mechanism inside the tube or the baffle tube?

Well welcome to TSS Ananth
Not sure how the focuser has fallen inside the tube unless you removed the focus knob ? the only way is if one the retaining washers break that hold the primary mirror , that can happen if one just turns the focus knob too far , these telescopes focus by moving the primary (big) mirror up and down by using a screw method that is attached to the mirror with a small hole in the glass
They are quite easy to take apart the top corrective lens just screws of and the rest is some bolts/screws , but remember to replace everything in the same place ! so mark the front lens and primary mirror to be the same
I once was given a 100 Mak for around 10 US including a small EQ mount , where the focuser did not work , when I took it apart the washer holding the mirror broke from the shaft , after some solder all was good
The compound scopes SCT And Mak's need a lot of focus travel between looking at stars etc and something close so people tend to move the focus knob too much and sometimes it breaks

Interesting as I own a SW 90mm myself. If you can't repair it yourself, it might be less expensive to just buy a new one. Let us know how it goes.

I am still perplexed on how the focuser fell inside the tube perhaps the OP (Ananth) can post a few picks ? that is if he wants any help

pakarinen wrote: ↑Wed Jun 01, 2022 12:39 pm Interesting as I own a SW 90mm myself. If you can't repair it yourself, it might be less expensive to just buy a new one. Let us know how it goes.

The cost of new scopes has gone up ,perhaps not is US so much but here in RSA and probably India is like 2x or more

Prices are much more in India, just looking around my Vixen is 2.599,00 €, in India it is 356,268.00 Rupee or 4.314,85 €

Thanks all for the updates.

Possibly I did turn the focuser moire than I should have. Along the way, I found the knob slipping , so I sort of tightyened the knob holding screws, but as I started moving now, the assembly/rod/shaft or whatever fell in !!
The original supplier - in 2007 !- declined any repair, but I have a possibility of getting the service manual from SkyWatcher.com India.

Shall still try and open it based on this manual hopefully and will update you.

Ok thanks for the picture , I have never seen this , the back plastic housing has a hole for the focus shaft to which the focus knob is attached , to break the entire hole in the back housing needs a lot of force
Anyway remove the 3 allen screw and the plastic back housing should come off then you can see what happened , the other 3 holes are collimation to adjust the primary mirror , so leave them alone for now
Then see if the hole can be glued back in place , it may need some 'reinforcing' from the back but certainly doable
With plastic I use superglue with some black powder , sold in many stores

I see you have a correct view diagonal on so changing from say bird watching to star gazing require a lot of turns of the focus knob where one that is not used to these scopes may go too far and then break things , in future if the focus knob does not want to turn smoothly and is hard to turn then stop and turn the other way , practice make perfect

Update

I opened the back cover by removing the 3 philips head screws on the side .
I also opened the allen screws maybe that was not needed?
Anyway, I could see the focuser I think well inside the tube, but could not pull it up or out to reach the back cover.
Is it that I have to unscrew the whole way ...
Attaching photographs of the disassembled back cover and back "flange" with a screw thread at the bottom.

Scared to go further, so reassembled for now.
Richard,maybe you can advise next step!!
Thanks.

Ananth

Just to complete the status, I do have the knob and washer as in attached.

I see that the mirror has broken away from the backing plate (the one with the tube that is next to the scope on the 2nd photo
There is nothing holding the mirror so should come out
The backing plate is attached to the back with those 3 Allen screws and the end of the focus is fixed to the plate , when you rotate the focuser it moves the mirror up and down , but not as far as the mirror has fallen now
Here is a pick of a 90 Mak its a meade ETX 90 so a bit different but may give you an idea

Just to add if the mirror does not want to come out as its wedged in then remove the front lens , most just screw off but yours has some plastic cover over , then may be easier to remove the mirror
This is quite a serious problem and the scope will need to be collimated after
I have never worked on a skywatcher Mak , but comparing it to an ETX Meade , or a others that were much older looks like quality is going down as the scopes get newer , more and more plastic and I dont see any collimation screws?
Here is a picture of the adjustments for a ETX (I had to take it apart as it was dirty and had creepy insects inside)

Thanks lots of information to understand so expect me to proceed slowly

Will update after working through.

Ananth

Hi all especially thanks to Richard,

Successfully got the focuser reinstalled.
Partly by luck, partly analysis, I moved the focuser control fully inwards and somehow the mirror assembly popped loose.

Was then able to reassemble the rod, the washers, and the knob.

I am not still terribly view quality assessment expert, but terrestrial objects seem to focus just like before, quite sharp and bright.

I do feel the telescope quality of material and assembly is quite good, based on this experience, also on the many times I have dropped the whole unit with eyepiece and all attached from at least table/tripod height, and absolutely no damage happened.

Hope to now progress to more frequent viewing, attaching camera etc.

Glad you got it working