Meade LX200 Classic Declination and Power Problem

[EJB]

Hope someone can help. I bought a used 10 inch Meade LX200 in Jan 2011 and set it up tonight for some viewing.  Immediately after I turned on the power switch the instrument began rotating forward and the key pad started blinking.  Panicking, I turned it off.  I switched it back on and it seemed to be okay.  I did a normal 2 star alignment and did some viewing without any problems.  I pressed star 906 to look at Saturn and the instrument started moving in both R.A. and declination in what can only be described as out of control and the keypad started blinking.  I turned the power switch off and waited for a few minutes before turning it back on. As soon as I did the instrument took off on its own again and the keypad started blinking.  Any ideas or suggestions would be greatly appreciated. 

Ed

[lindendave]

Howdy Ed,

There is a good deal of knowledge here and I am sure that suggestions and recommendations will be coming shortly. In the mean time I will begin to shake the bushes and make others aware of your post.

[EJB]

Sir, thank you.  You answered my last post about a transport system which I built so I use the scope quite frequently. This problem caught me completely by surprise.  The scope just seemed to "run away".

Thanks again, Ed
Marion, Texas

[drclay]

This, because it is repeatable but not predictable, sound like one of two things:

1) a bad power supply (my guess)
or
2) a loose wire or connection in the base.

Both are worth looking into.

What are you powering your scope with?  Is this a GPS or the older Classic model LX200?

Without question, the most common problem with either of these two models is the power source; you must have 13.8 volt regulated power going into the scope at all times; either a jump start battery (rechargeable, available at Wal Mart), or the regulated power sources from Radio Shack, Pyramid or www.scopestuff.com

Open the base up and jiggle the wires and look at every connector...one of them simply may be loose.

If this is a GPS model, NEVER use the internal batteries for power.

Best of luck and get back with us on this......I have been away, so sorry about the delay.

Doc

[EJB]

Dr. Clay, it is the classic model.  I am using the power source that came with the scope. The power supply is manufactured by Sceptre. The label indicates it is a Class 2 transformer input 120VAC and output 18VDC. Thanks for the advice.  Hopefully I can get the scope to behave tonight.

Respectfully, Ed

[lindendave]

Ed,

Doc recently helped another person with a classic scope. Rather than quote all that he said, please read the post entitled; HELP! Dead Scope. Though I do not own a classic I can attest to a couple alternate power sources, Radio Shack and Pyramid. I personally own a Pyramid PS15KX 10 Amp with which I power everything but my scope and I have an older Radio Shack 12v 2.5 Amp supply just for the scope, I do not think that model is still available though. I think either of the two supplies on the following link would work for you but perhaps Doc has other recommendations.

http://store.valueweb.com/servlet/buyreliant.com/Categories

[EJB]

Dave, thank you.  I am looking for a new power supply.  I did as Dr Clay advised and pulled the cover off the panel.  From a visual inspection everything looks to be in order. Nothing loose.  Appreciate the help. I'll give you an update once I get a new power supply.  Hopefully it remedies the problem.

thanks again, Ed

[drclay]

That old Meade power supply was very problematic and 90% of all problems associated with the Classic Meade were from using that power supply.  First of all, the scope does NOT function well with 18v; that is too much voltage particularly unregulated.  It can spike up to 24-27 volts at times and the circuitry simply cannot handle it.

The Classic scopes can run far better off of a good regulated 12 volt system.  The slews are quieter and far more efficient, only a bit slower with 13 volts or so.  13.8 volts is ideal, which is what the Radio Shack, Pyramid and the jump start batteries all put out.

Just make sure you are using a center pin positive plug, 2.5mm i.d. x 5.5mm o.d. (the Radio Shack "N" plug).

Dr. Clay

[EJB]

Dr. Clay, thank you for the advice.  I'm off to Radio Shack with a printed copy of your reply.

Respectfully, Ed

[EJB]

Dr. Clay and Dave, I purchased a new power supply from Radio Shack. I just plugged it in and powered up the scope. There are four bars showing on the ammeter.  I used the keypad to move it around and it acts normal. The old power supply never showed more than three bars.  Just for curiosity sake I took the old power supply to my neighbor's and he tested it with his voltmeter. Sure enough, it was all over the place with a reading as high as 20. Hoping to get home early tonight and take advantage of clear skies.

Thank you for all of your help.

Respectfully, Ed

[lindendave]

Ed,

I know I speak for Doc too, you are more than welcome. I can not begin to explain how much wisdom I have picked up, well lost some too, from the good doctor.

I can tell you from personal experience with AC/DC power supplies that it will be in your best interest to test them from time to time. I had a 10 Amp Radio Shack supply that I powered everything but the scope with go bad once. It failed and started putting out in excess of 20 Amp of current and melted the eyepiece on my finder scope and base of my Telrad finder. Since then I try and do monthly inspections of my power supplies and all the wiring and connections.

[EJB]

Dave, thanks for the advice.  Being new at this I have a lot to learn. I will definitely do as you suggest and conduct a test on the power supply as part of my routine.  The skies here are clear today and I am hoping they stay clear this evening. I am anxious to try the scope out tonight.

Warmest regards, Ed 

[EJB]

Doc. Clay and Dave,
I finally had the opportunity to take the scope out and try the new power supply.  It is a regulated 12 volt power supply from Radio Shack. It worked very well. The scope moves a bit slower but it is quieter. The good news is the scope didn't "run away" as it had with the old power supply.  I had a great night.

Thanks for all of your help.

Ed 

[lindendave]

I'm sure I speak for Doc as well when I say you are most welcome!

Regulated power supplies and Meade telescopes just seem to go hand in hand.

Enjoy the night skies!