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Advice Needed on High School Astronomy Club Observatory Scope: Meade LX200r

cassegrain catadioptric equipment
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#1 sclausen

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Posted 04 December 2019 - 02:41 PM

Here is the situation:

 

We have a 12" Meade LX200R that was bought and installed on a pier back in 2005, I believe. There seems to be two main issues with the scope:

 

1. As is the case with many of these larger SCTs, the focusing is just not working all that well. The fov shifts rather than the image coming into focus. You can sometimes wrestle it into focus, but it very quickly loses its focus again (and forget about changing eyepieces on the fly during a star party ... ). I've looked into this issue, and it sounds like there may be some potential solutions, just about all of which requiring I take the thing apart, which I'm not entirely eager to do but will try to figure it out if need be.

 

2. We have had a tough time getting the GPS / tracking to work. We can usually locate an object manually, ID it in the catalogue, and then select "track", and it will follow the object okay. But any attempts at aligning the scope using three stars have not gone well. And anytime you select an object for it to slew automatically to, it turns all around, twisting the wires and usually ends up upside down or backward, nowhere near where it's supposed to be. (Again, finding things manually works, but we'd like more people at the school to use it, and I'm not sure they're willing to learn the night sky.)

 

I've reached out to Meade, and they suggested we send the scope in for service, but we're not eager to do that either, as it will cost maybe about how much the scope is currently worth just in shipping alone. I've spoken to a few people in the area who have some experience with this scope, who basically recommended it may be time to look into getting the new and improved version, which is not impossible. (We would just have to make a case for it.)

 

What would you do? Try to get this thing back on its feet, even if the focuser and software seem outdated? Send it off to Meade despite the cost? Try to sell our current scope and buy an updated version, like the LX200ACF or LX600 with Starlock? (Apparently the latter has fixed the image shift issue, and I've also heard the software has come a long way since 2005 –– a newer version will be way more user friendly and will get more use at our school.)

 

We have a meeting to discuss the issue in a few days, and those in charge seem to be leaning more toward trying to fix the scope we have (obviously), which is why I'm trying to come up with a compelling case for why it makes more sense to update our equipment.

 

Any advice would be greatly appreciated!



#2 macdonjh

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Posted 04 December 2019 - 03:25 PM

If your existing scope has mirror locks, perhaps adding an aftermarket Crayford-style focuser and locking the main mirror would solve your image shift problems.  There used to be aftermarket mirror locks available, too, if you're willing to do some modification to the telescope.

 

Have you investigated the GPS bug?  Lots of LX200 mounts went haywire a few months ago because the GPS system reset its date codes and suddenly the mounts all had the wrong time so they didn't point where they were supposed to.  You can search in the Cloudy Nights forums for help with that.  I wonder if you could connect the existing LX200 mount to a computer or I-Pad and run SkySafari on it?  That would be really intuitive for a bunch of high school kids.

 

I'd volunteer to fix the mechanicals of your scope, but it's a long drive between where you and where I am.  There really isn't much in these SCTs that can go wrong and not be fixed.  I'd hate for you to decide to replace a scope that could be fixed.


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#3 jgraham

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Posted 04 December 2019 - 03:37 PM

What kind of condition is the scope in? 14 years of high school service can be rough. The focus issue sounds like mirror flop which I would not expect to be too bad in a scope this age unless the grease on the slides has dried out. This can happen if the scope has sat idle for long periods of time.

Is this scope mounted as an altaz or on a wedge? Anywho, I'd try skipping the GPS and auto-align and try to do a manual 2-star alignment. If someone opened up the mount in the past they may have installed the LNT board upside down. I've seen this a lot. (It looks upside down when properly installed.) You might consider resetting the controller and starting from scratch.

You might ask in the Meade Forum for help, there are some very knowledgeable folks there. You might also see if there is a local astronomy club that can help.
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#4 photoracer18

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Posted 04 December 2019 - 03:48 PM

I agree. I have done observatory scopes up to 16" SCTs while working for Hands On Optics but WV to Vermont is not doable. You don't want the mileage charge.lol.gif



#5 Astro-Master

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Posted 04 December 2019 - 04:44 PM

I would sell the Meade Schmidt Cassegrain you have and buy a new Celestron 11" on a CGX mount.  You can order it through Company 7 on the East Coast near you.

 

They will inspect and adjust everything on the scope at no extra charge.  Problem solved


Edited by Jaimo!, 05 December 2019 - 09:07 AM.

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#6 jgraham

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Posted 04 December 2019 - 06:58 PM

Wow, really?

Moving on...

#7 gfstallin

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Posted 04 December 2019 - 09:04 PM

If you aren't particularly handy with electronics and mechanical things, then you could sell it as is. There are people who could use it for parts, perhaps even locally (to include Montreal and environs as well as greater Boston and upstate NY). While the scope might very well be capable of being brought back to acceptable service, getting the telescope to people who can get it that way is prohibitively expensive. 

 

Another option might be to detach the OTA from the LX200 mount. Send the OTA to Meade for a good cleaning and to fix any issues you have with the focus mechanism or mirror flop. I suspect round-trip shipping will be in the $300 range. You can get an EQ-6 (the smallest mount capable of holding a Meade 12" OTA) for around $800 + shipping used.

For info on the EQ-6 with a Meade 12" OTA, see https://www.cloudyni...-2#entry8369118. Another informative page for that setup is https://www.cloudyni...12-inch-lx90/. 

 

Even if you bought a new EQ-6 for about $1,500, that still brings you in below $2,000. 

 

The elephant in the room here is what Meade will actually charge you for servicing the telescope. I suspect it is well outside of warranty. A new C11 on a CGX under warranty will run you about $4,200. You could get a clean used C11 for about $1,200 and that used EQ-6 for about $800 (an EXCELLENT visual and planetary imaging combination I used for a few years). With shipping you'd still be below $2,500. There is a certain price that only you can name at which it would not make any sense to pay Meade for servicing the telescope. 

 

Also, not to sound out of touch, I realize these might be pretty high numbers for a high school observatory/club and a lot of folks - myself included. Even private schools don't necessarily throw that kind of money around. 

 

George


Edited by gfstallin, 04 December 2019 - 09:06 PM.


#8 OzAndrewJ

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Posted 04 December 2019 - 09:27 PM

Gday sclausen

 

The fov shifts rather than the image coming into focus.

Have you released the mirror lock fully????

If so, the sled rides on a layer of grease, and this can harden a bit over time.

The quickest way to fix it ( minimal disassy ) is to use the focusser to push the mirror as far forwards as you can.

Then remove the 3 screws holding the focusser to the OTA

You can now pull the focus knob backwards and it will pull the mirror sled back

Now just push the knob back in and pull it out again half a doxen times or more.

This will redistribute and freshen the grease layer, and you should feel the resistance reduce as you do it.

Refit the focusser and it should show a big improvement.

 

We have had a tough time getting the GPS / tracking to work. We can usually locate an object manually, ID it in the catalogue, and then select "track", and it will follow the object okay.

Need more info, as that sounds weird. There is no need to select "Track"

After aligning, the mount is automatically tracking, and on finishing a goto, it just resumes tracking.

Assuming you are mechanically polar aligned, you should be able to do a faked polar one star

( ie when it tells you to adjust the wedge on Polaris, just hit enter )

and then centre the next star, all should be well.

Also, as noted, ensure the time is correct after getting the GPS fix ( set it to "At Start" )

as if you have the GPS rollover bug, you will need to patch the firmware to get around it.

 

Andrew Johansen Melbourne Australia



#9 sclausen

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Posted 04 December 2019 - 09:33 PM

Thanks for all your thoughtful advice –– really appreciated.

 

I'll try to address each of the points raised:

 

To macdonjh: The scope does indeed have a mirror lock and an electronic focuser that I believe was purchased with the scope –– the latter does not seem to be working, though it is making sounds when I try to focus using the paddle. Would a Crayford have enough in and out travel to bring the image into focus or is that mostly for fine focus? (I only have experience with this kind of focuser on a dob, and it works like a charm in that case.) That is an appealing idea, especially since the mechanics are right there in front of you, which is way more my style. I was not aware of the GPS issue –– good to know; I will look into that.

 

To jgraham: Aside from some dust the optics seem to be tip top. I do believe the scope has sat idle for long stretches so there's a good chance the grease is dried up. I imagine the only fix for that is taking it apart and reapplying lubrication, yes? How difficult is that? I've never taken apart an SCT before. It's currently on a fork / wedge mount setup, and I'm not sure if anyone has messed with the LNT board. My guess is no, though, since there really isn't anyone around who would have been messing with the scope all that much.

 

To Astro-Master: I have considered the Celestron option, and I know some are partial to them over Meade. Not sure if giving up an inch in aperture matters all that much ... maybe I should just go ahead and upgrade to 14"! (I kid –– plus, the observatory shutter, built for a refractor back in the day is probably a little too narrow to go any higher in aperture.)

 

To gfstallin: Thanks for your input, as well. I did look into the cost of shipping the scope back to Meade for service. They said they charge $300 to ship it BACK, but I would have to figure out the shipping to get it there, and they dropped the hint that others have spent as much as $700 to get it there. And then something like $500 for the service. Anyone know how likely it is that they will actually be able to fix the focus issue, so that it doesn't happen again? Is mirror flop / image shift unavoidable in these scopes (so I've read)? That's why the upgrade to a newer model is so appealing, because it sounds like they've taken care of this issue –– according to the description/specs for the LX600 they have, at least. Regarding the money, it's a donation situation. The same generous folks who donated the scope about 15 years ago heard that the observatory wasn't being used as much as it should be and heard about the scope issues (and about the trees blocking the southern sky) and said they were willing to pay to get things back up and running. So it really comes down to what they're willing to pay for. That's why I want to do my homework, to let everyone know what the options are ...

 

... so this is all hugely helpful. Thanks again!


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#10 sclausen

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Posted 04 December 2019 - 09:41 PM

Hello to you, Andrew Johansen.

 

The mirror lock is released fully. It does sound like the thing has just kind of gotten stuck –– the grease issue is definitely worth trying to take a look at. When you say "the three screws holding the focuser to the OTA" do you mean the actual knob? or ... something else? I'm going to give this a try (as it is the second or third time I've read this piece of advice –– it must be working for others!)

 

Regarding the GPS / tracking ...

 

It does sound sometimes like it's tracking, but it doesn't hold objects in the FOV for very long, so if it is, it's not doing it accurately. I think I need to try to reset it somehow, go through the manual and start from scratch getting the thing aligned.

 

Some things to try ...

 

Thank you for chiming in!

 

Scott



#11 OzAndrewJ

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Posted 04 December 2019 - 10:05 PM

Gday Scott

 

When you say "the three screws holding the focuser to the OTA" do you mean the actual knob?

Yep

The knob is just like an oversized nut, with a threaded rod inside it.

This rod attaches to a pin/bracket on the rear of the mirror sled

Ref http://rainydaymagaz...s-knob-upgrade/

The top right of the 4 pics shows a stainless rod with a hole in it.

That is basically what the std Meade mechanism looks like internally

The pin/bracket on the sled fits into that hole and then the rod moves in and out of the knob to move the sled

Soooo, once the knob is removed, you can manually push and pull the sled as far and fast as you like

to redistribute the grease

 

 

It does sound sometimes like it's tracking, but it doesn't hold objects in the FOV for very long, so if it is, it's not doing it accurately.

How long does it take to move out of the FOV???

In Polar, it should stay in the FOV for a fair while, as its only moving at a set speed

Need more info

What firmware rev is it running ? ( Under the "Statistics": menu )

 

Andrew Johansen Melbourne Australia



#12 dr.who

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Posted 04 December 2019 - 10:30 PM

If you decide to purchase a new scope, instead of going to Company 7 (a very good vendor!) I would suggest you give this site’s sponsor, Astronomics, a call. They offer a discount to members of CN and may offer an even larger one since you are an educational institution. I would second the recommendation of a Celestron 11” SCT on a CGX mount.
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#13 sclausen

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Posted 04 December 2019 - 11:01 PM

Gday Scott

Yep

The knob is just like an oversized nut, with a threaded rod inside it.

This rod attaches to a pin/bracket on the rear of the mirror sled

Ref http://rainydaymagaz...s-knob-upgrade/

The top right of the 4 pics shows a stainless rod with a hole in it.

That is basically what the std Meade mechanism looks like internally

The pin/bracket on the sled fits into that hole and then the rod moves in and out of the knob to move the sled

Soooo, once the knob is removed, you can manually push and pull the sled as far and fast as you like

to redistribute the grease

 

How long does it take to move out of the FOV???

In Polar, it should stay in the FOV for a fair while, as its only moving at a set speed

Need more info

What firmware rev is it running ? ( Under the "Statistics": menu )

 

Andrew Johansen Melbourne Australia

Useful info –– I'm going to give that potential fix a go (seems totally doable, that).

 

Regarding the electronics / software ... this is the area I'm not too familiar with, which is why I may be having some trouble getting it to do what I want it to do. I think I just need to spend some time with the manual, and I'll get back to you ...

 

Thanks again,

s.



#14 sclausen

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Posted 04 December 2019 - 11:01 PM

If you decide to purchase a new scope, instead of going to Company 7 (a very good vendor!) I would suggest you give this site’s sponsor, Astronomics, a call. They offer a discount to members of CN and may offer an even larger one since you are an educational institution. I would second the recommendation of a Celestron 11” SCT on a CGX mount.

Good thinking!



#15 macdonjh

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Posted 04 December 2019 - 11:03 PM

 

To macdonjh: The scope does indeed have a mirror lock and an electronic focuser that I believe was purchased with the scope –– the latter does not seem to be working, though it is making sounds when I try to focus using the paddle. Would a Crayford have enough in and out travel to bring the image into focus or is that mostly for fine focus? (I only have experience with this kind of focuser on a dob, and it works like a charm in that case.) That is an appealing idea, especially since the mechanics are right there in front of you, which is way more my style. I was not aware of the GPS issue –– good to know; I will look into that.

 

First things first: it may be simplest to remove the electronic focuser and see if the manual focuser works smoothly.  As I said, there isn't much that can go wrong with these scopes.  The manual focuser is simply a threaded rod, unless something is stripped if you can turn it, it will work.

 

I put a Crayford focuser on my C11, I liked the addition.  I bought a MoonLite and orders a 1 1/2" long draw tube.  Once I had it installed I put my longest focal length eye piece in, racked the Crayford focuser all the way out, then used the stock focuser to bring a star to focus.  Then I swapped to my shortest focal length eye piece and used ONLY the Crayford focuser to bring the same star into focus (racking the focuser in).  All my eye pieces thus came to focus with the Crayford and I never had to touch the stock focuser knob again.


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