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Meade LX200 Classic sparks

Started by speleopower, 06/24/2009 06:16PM
Posted 06/24/2009 06:16PM Opening Post
What just happened to my scope. I had everthing plugged in and ready to go. I turned on the power and there was a loud Poof and a spark coming from under the front cover. When I pulled the cover off thinking it was a burned fuse I found one of the small yellow "resisters?" was burned. The picture I attached show me pointing to the offending part with a probe.

Did I just lose my scope for good? Any idea what just happened?

I feel like I am going to throw up. Telescopes don't seem to be my things.
Scott

Attached Image:

speleopower's attachment for post 47293
Posted 06/24/2009 08:58PM #1
Looks like it is just a bad capacitor. Probably tantalum. Fairly easy to repair and cheap as long as nothing else got fried.

This is not a very frequent problem on these scopes but bad caps are the biggest problem on pc boards.
Posted 06/25/2009 12:50AM #2
Scott Bauman said:

What just happened to my scope. I had everthing plugged in and ready to go. I turned on the power and there was a loud Poof and a spark coming from under the front cover. When I pulled the cover off thinking it was a burned fuse I found one of the small yellow "resisters?" was burned. The picture I attached show me pointing to the offending part with a probe.

Did I just lose my scope for good? Any idea what just happened?

I feel like I am going to throw up. Telescopes don't seem to be my things.
Scott

Scott:

First, yeah, sparks are scary, not doubt about that. Hopefully, as Ron says, it is just a bad capacitor which is relatively easy to replace and is readily available. But there is some chance that the capacitor blew because another component failed.

Replacing that capacitor should be done by someone who is reasonably skilled, I doubt it is anything too fancy like a multilayer board so anyone with moderate soldering skills and a good quality soldering setup should be able to take care of it.

Jon
Posted 06/30/2009 05:49AM | Edited 06/30/2009 05:56AM #3
I just noticed in the new issue of Astronomy Technology Today that an outfit called The Astronomy Shoppe has begun specializing the the repair of classic Meade LX200's.

Scott, check your private messages.

Oklahoma State University--The University of Oklahoma!--GO POKES!! GO STATE!!
Posted 08/02/2009 08:34PM #4
Scott Bauman said:

What just happened to my scope. I had everything plugged in and ready to go. I turned on the power and there was a loud Poof and a spark coming from under the front cover. When I pulled the cover off thinking it was a burned fuse I found one of the small yellow "resisters?" was burned. The picture I attached show me pointing to the offending part with a probe.

Did I just lose my scope for good? Any idea what just happened?

I feel like I am going to throw up. Telescopes don't seem to be my things.
Scott


This is just so easy! There are 16 of these caps throughout the scope. One on each encoder motor board, two on the power panel, three on the hand controller and nine on the main board. They are ALL the same value. Replace with the same type 6.8uf 35v. I just replaced all mine yesterday.

To remove, heat up a soldering iron -- while it's warming up, get a magic marker and mark the location on the bottom of the board. Add just a bit of solder to the joint (old solder is a bit more difficult to remove) and get either a solder sucker or copper braid solder remover.

DO NOT heat the joint too long. A few seconds at a time, perhaps 5 or 7 is okay. If you heat it too much you'll lift the via from the board and you'll have to rework the area with wire to jumper between paths.

If the solder doesn't come all the way out of the hole, heat it up just a bit and whack the board on something to remove the solder.

Install the new part (OBSERVE POLARITY!!) the silk screen mask will indicate which side is which.

Trim the leads and reinstall the board.


If you are uncomfortable doing this, mail it to me and I'll have it back in the mail the same day at no charge. I've got quite a few of these caps left over...they cost me less than 10 cents each. I've been soldering since I was 6 and I'm rather good (I've had 30 years to practice!)



A photo of the cap I used is included.


Phil Godfrey
St. Louis, MO.

Attached Image:

pmgodfrey's attachment for post 131746