12” Meade LX200 EMC Scope to go Under Repair

By Warren Bracewell

On Tuesday, December 31, 2019, Dave and Mitchell Barry, Jim Lamar, Tim Cowden, and I met Chris Haas at his ranch to pick up a 12" Meade LX200 EMC telescope and pieces of an observatory, all of which had been stored in a pool house bathroom. When we loaded the telescope into my truck, I asked about the cables and accessories. I went back to the pool room and, after some searching around, found two boxes with Meade products in them. I took the scope home and Tim Cowden helped me unload it into the garage. The next day, I started doing an inventory of what we had and what was missing. This is a run-down on the condition and completeness of the project.

First, what we have.

The telescope appears to be in fair condition. I cleaned all of the dirt dauber nests off of the exterior and lifted it up onto my table saw so that I could check it out.
It has the front lens cover and an eyepiece hole plug.
Attached to the eyepiece hole is an electronic focuser with no wires.
The scope has two full length Losmandy mounting rails attached to the top and bottom.
It also has a wedge attached to the scope.
There were two hand controllers in the box, one marked “good,” so I am assuming the other is bad. Neither of these controllers had the connecting cable to attach to the scope.
There is a two holed plate that fits on the front of the scope that I assume is a Hartmann mask for focusing.
There is a long threaded rod with a handle and a three-pointed plate that is used for mounting the scope to the tripod. I figured this out by downloading the owner's manual.
In one of the boxes, there was a motherboard and two drive motors. I am assuming that these are RA and DEC drives, but they are not marked and look the same.
There was also a box that contained two chips that was labeled 64K object software library.
The other box has a variable Tele-extender tube with a Nikon mounting ring attached.
It also had an 12mm illuminated reticle eyepiece with a 6' wire attached that I assume attaches to the reticle port of the scope.
The other item in the box was the electronic DC adapter. This is a 12V to 18V converter with a 12V cigarette lighter plug on one end and a connector that fits the telescope on the other.

Now, what we don't have.

No lenses other than the lighted reticle lens.
No diagonal.
No tripod. This is a big deal because this scope is HEAVY. It will take a beefy tripod to support it. Chris Haas, who we got the scope from, said that he remembered seeing one and was going to look for it. If we decide to permanently mount it somewhere, we wound have to get a pier plate.
There were also no wires or cables other than the power cable. I took it upon myself to order cables for the DEC motor and the hand controller.
No AC adapter.
There was a book in the box for an off-axis guider. The pictures show the lighted reticle and the tele-extender attached to it, but it was nowhere to be found.
There is a mount for a Telrad and for a spotting scope, both of which are missing.

Dirt Dauber Nests and Spider Webs

Once the dirt dauber nests were cleaned off and the scope given a damp cloth cleaning, the exterior looks in good shape. The front correcting plate is dirty inside and out and there are spots on the primary. There are also spider webs inside the scope between the corrector plate and the primary that, I'm sure, would affect the viewing. I could remove the corrector plate and clean out the webs as well as clean the corrector plate and the primary, but I am sure that would affect the collimation.

Maybe I can get some assistance from somebody that has a little more experience with lens cleaning. That's it for now. Once I get the cables I ordered, I will try to power it up and see if it even slews.

January - It's Smokin'

I received the cables in January and hooked up the scope using the old hand controller.

I turned on the power and it started out fine; then the amp indicator went high and the controller started smoking. I jerked the power cord out of the scope and investigated. A capacitor in the controller had shorted and also burned the ribbon cable. I checked to see why the fuse didn't blow and found a 3 amp fuse in the holder. I checked the web sight and Meade recommends a 1.5 amp slow blow. I guess I should have checked that first, but had no reason to believe it was the wrong fuse in there. I took the front cover off of the panel and checked that fuse. It was a 1 amp, which it is supposed to be. I am pretty sure it was a controller problem since the other fuse did not blow. I will try to find a schematic and see if I can back trace the problem. I have ordered the right fuse for the power cord, but I am now afraid to try the hand controller that was marked new until I figure out what is wrong.

On another note, I took the scope outside and set it on my table saw since we have no tripod. I roughly polar aligned it and strapped it down with a ratchet strap. Using it manually with my lenses I was able to check the collimation and it was spot on, which is amazing considering how much it was moved. The sharpness appeared to be pretty good, too.

The Next Steps

I got the correct fuse for the power supply and installed it. I put the other hand controller on and installed the dec cable. I powered the scope up and at least it didn't blow.

The display came on and just read “Meade.” It is supposed to activate the DEC and RA motors and cycle them for a bit and then display “TELESCOPE OBJECT LIBRARY.” I checked on the forums and there could be several issues from the motherboard, the power board, or either of the drive motor boards.

There were “new” drive motors and boards and a motherboard in the box. To change the motherboard, the scope has to be removed from the wedge. This is a two person job and I’ve spent about as much time as I'm willing to invest.

On another note, Tim has volunteered to repair the blown hand controller. He also leant me an electronic focus controller to try out the focuser. I plugged it in and, of course, it didn't work. I took it off of the scope and the drive was frozen solid. A little oil and working it freed up the gears, but the motor still would not turn. I got the information off of the motor and checked with the manufacturer and the motor is no longer available.

If anybody else has any ideas or wants to take over this project, let me know because I need my work bench and garage back.

Tim Cowden Takes a Look

More not so great news. The hand controller is not an easy fix. The keypad is made of a conductive paint silk screened onto a plastic substrate. Soldering won't work, a conductive epoxy might work. I did replace the bad caps. I'm willing to look at the motor focuser.