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Meade LX200 Classic RA runaway

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#1 Eddie Murdock

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Posted 26 January 2014 - 12:01 AM


Hi all. Thanks to letting me part-take in this site. I have read a few posts and realized I needed to be here.

I just bought my first telescope (10", LX200 f/6.3, 1600mm on Alt-Az) to start doing AP with. I have been doing wide angle AP with general camera equipment and really wanted more 'reach'.

I bought this knowing it was going to be a fixer upper based on it being a runaway. I thought I would either send it off to be fixed, fix it myself by learning how it all works or just ditch the fork and mount and get a decent EQ for it.

Was hoping to hear if anyone knows who to turn to in properly diagnosing what is wrong so I can keep the cost down on repairs.

My ultimate goal for this scope is to do stack long exposures of nebula, galaxies and whatever else in reach of this particular scope.

I hope I didn't post in the wrong section, sorry if I did. just a noob. ;)

#2 zerro1

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Posted 26 January 2014 - 01:16 AM

I would take a look in this thread http://www.cloudynig...t/0/Board/Meade

I had an LX90 that was doing this. Replaced the controller and solved it. That isn't always the case though. First off the 200 uses a different controller(handpad). I've heard of it also being a problem on motor boards. Like I said try the other thread or ask a moderator to move your question there. You would be better served with an GEM/EQ mount for imaging unless you have an exceptional example of a LX200 but that is my opinion.

#3 fishonkevin

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Posted 26 January 2014 - 09:10 AM

Eddie, welcome to Cloudy Nights. We have a Meade LX specific forum here, and you probably get better replies/feedback there. I would be happy to move your thread for you. Let me know.

#4 Eddie Murdock

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Posted 26 January 2014 - 02:12 PM

That would be great Kevin! thank you!

#5 *skyguy*

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Posted 26 January 2014 - 02:35 PM

The MAPUG - Astronomy Topical Archive ... will give you just about all the information you'll ever need on the Meade LX200 scopes:

MAPUG

Scroll down to the bottom and on the left side look for the topic ... "RA Axis/Drive Concerns (Tracking)" which has a lot of info on the RA runaway problems.

#6 astrojim1

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Posted 27 January 2014 - 03:06 PM

Look for the simplest causes first. For example, on occasion, I have found that my runaways were caused by stresses on cable lines that caused the wires in the contacts to cross up. This is especially true in the HDBX cable contacts. Just by reconnecting them after removing the stress, the problem was solved.

Jim

#7 Live Oak Imaging

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Posted 28 January 2014 - 11:35 AM

There are multiple possible causes. A cause that I have personal experience with is the 20 MHz crystal not oscillating on the RA motor control board. Common causes are a bad crystal or bad C1 or C2 capacitor. If the 20 MHz is not present, the mount goes into immediate RA runaway. The RA motor control board is located under the base of the mount next to where the RA shaft ends. The board is about 4" X 1.25".

#8 Live Oak Imaging

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Posted 28 January 2014 - 04:46 PM

I made an error in my last post as I did not realize the discussion pertains to the "Classic" version. This version would have RA runaway if it lost the encoder signals form the RA motor speed encoder.

#9 Eddie Murdock

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Posted 28 January 2014 - 07:04 PM

While waiting to figure out if it is even really worth fixing this runaway problem, I am looking at just getting an EQ mount and an OTA clamp and dovetail. As well as tripod. What are some good ones to look for and what should I avoid? I have up to $1600 budget. Again, this will be strictly AP.

#10 nitegeezer

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Posted 28 January 2014 - 10:22 PM

Looking at your location, I bought my scope from Anacortes Telescopes and Wild Bird several years ago. I still buy accessories through them and have called them with questions on numerous occasions. I am a long way from a dealer, but I have always found them very helpful. I just found out about them via the Meade dealer page and have been very happy with them. It might be worth a call to them and see what they say, it can't hurt.

#11 Eddie Murdock

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Posted 28 January 2014 - 11:00 PM

They are actually who I got my scope from but they suggest the ioptron eq45, which I am sure there is something a little bit less expensive.

#12 nitegeezer

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Posted 29 January 2014 - 12:54 AM

I have never been to their store but they have talked me through repairs a couple of times. Have they looked at your runaway condition, or is their shop time unreasonable?

#13 Eddie Murdock

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Posted 29 January 2014 - 10:42 AM

They said it would probably cost me $600 to have it sent off for repair. I don't know about you, but shipping a big piece of optics like this is not something I feel comfortable doing, especially if it UPS/FedEx/DHL. I know several electricians and I&E techs that would be able to help diagnose and repair this. No need to send off and risk damaging it. I would rather drive it myself. That being said, I wonder if their is a repair shop around Seattle.

#14 nitegeezer

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Posted 29 January 2014 - 11:57 AM

With some of the help they have given me over the phone, I thought they might have a repair shop there. I agree with you, I would have a hard time sending my scope in for repair. If it ever fails to the point I can't fix it, like you I will be looking for a EQ or weighing other options. I hope you can find the problem.

#15 SteveRosenow

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Posted 29 January 2014 - 12:56 PM

They said it would probably cost me $600 to have it sent off for repair. I don't know about you, but shipping a big piece of optics like this is not something I feel comfortable doing, especially if it UPS/FedEx/DHL. I know several electricians and I&E techs that would be able to help diagnose and repair this. No need to send off and risk damaging it. I would rather drive it myself. That being said, I wonder if their is a repair shop around Seattle.


I know that there's an electronics wholesale supply warehouse in Olympia that does minor electronic repair, however I am not sure if there's one in Seattle.

I think the $600 that Anacortes Telescope quoted was - I believe - the repair cost to have it sent to Meade down in Irvine, CA. That being said, Meade has distanced themselves from repairing the older LX-200 Classic models because the electronics in them are getting harder to source (yet usually, runaway problems are usually traced back to potentiometers that have gone out of adjustment or a bad capacitor).

There is an astronomer in Arkansas by the name of Dr. Clay Sherrod who does a "Supercharge" service on all of the older Meades, but to have it done on a 10-inch LX200 Classic is about $600 - and then you have to pay for shipping to and from Arkansas. And repairs are extra depending on the parts he has to source, plus labor, etc.

By the way, welcome to CN, Eddie! :)

#16 Starman27

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Posted 29 January 2014 - 11:32 PM

My LX200 RA runaway turned out to be dirty contacts for the hand box. Used electrical cleaner and the problem went away and has stayed away for the last four years.

#17 Geo.

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Posted 30 January 2014 - 10:34 AM

The last LX200 encoder I rebuilt wasn't that expensive. The priced items were what I replaced.

Attached Files



#18 Geo.

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Posted 30 January 2014 - 10:39 AM

This is the encoder signal before and after before and after rebuild. I'm a JD, Jim. Not an EE!

Attached Files



#19 Christopher Erickson

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Posted 30 January 2014 - 01:21 PM

This is the encoder signal before and after before and after rebuild. I'm a JD, Jim. Not an EE!


Those look like exactly the same signal only the O-scope triggering isn't set correctly in the top pic.

#20 wd8sbb

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Posted 31 January 2014 - 05:07 PM

+1 for O-scope trigger.

If this is a classic (sounds like it) then the most often overlooked issue is a bad connection. Carefully check the wires on the "punch down" connectors which connect the motor assembly to the rest of the scope.

Look at the bottom of this thread for a picture and discussion that occurred years ago among the MAPUG mailing list about RA and DEC runaway and the motor assembly.

Also a link to the MAPUG archives. Great LX200 classic resource, with some of the best of the old MAPUG mailing list. There is further discussion there on runaway as well.

Our LX200 was built in 1992. Still going strong with mostly just minor PM. I repaired our runaway years ago, it was the el-cheapo connector.

#21 Nemesis79

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Posted 04 September 2014 - 03:53 PM

http://thadlabs.com/MAPUG/ccdastro/

 

Bruse Johnson's Astronomy pages - Bruce (now sadly deceased) explains how the LX200 classic's RA & DEC work and how to trouble shoot them, especially run away problems. This is an excellent site for the LX200 classic series of Meade telescopes, especially, if you are a do it yourself type.

 

Robert Yearley



#22 Nancy Gayle

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Posted 11 September 2014 - 03:02 PM

I'd bet the handbox curly cord or it's connectors is the first thing I'd check. 








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