HELP! Dead Scope

[pbyrne]

Please help me.

I was observing tonight, I had the scope trained on a beautiful open cluster in Monoceros when I noticed that the cluster began to drift across the field of view, when I looked down at the Autostar I could see that it was dark and the voltage indicator, normally red, was also dark.  There was no power getting to the scope.  I had it connected to the mains via an extension cord, thinking this might be the trouble I changed the cord, the voltage indicator flashed for a fraction of a second and nothing.  Now I was thinking it might be the converter between the extenstion lead and the scopes control panel.  I got out my Powertank, connected it up and again the there was a brief flash and nothing.

By this stage I'm panicking, I removed the scope from the tripod, brought it indoors and connected it to a socket, once again a brief flash and nothing.

It seems to be that there is no power getting to the scope.

The scope of a Meade LX200 classic, perhaps 12 years old or so, the chap I bought it off said that there had been an electronic problem before, but he had it fixed.

I'm desperately in need of help as I know exactly nothing about electronics.  Can anyone help bring my scope back to life?

[lindendave]

I am totally unfamiliar with the classic scopes but I did put out a distress call to an authority on telescopes so hang in there answers and/or suggestions will be forth coming.

[drclay]

I am a bit confused by some of the information:
Is this a Classic LX200?
If so, the Classic version did not operate via Autostar but a large handbox; I am suspecting that you have the older Classic since you are indicating it has a power meter....if not, please advise.

Note that part, if not all, of the problem, comes from using a PowerTank or any such device; these are horrible power sources and subject to multiple damaging surges and spikes and are totally unregulated....you may have 12 volts one minute then a surge to 32 volts the next.

Also note that the Classic are best operated on a 12 volt or 13.5 volt power source, NOT the 18 volt as provided by Meade when they were sold; the components simply couldf not handle the 18 volt output and hence many had problems.

Now, back to your problem:  There is a fuse inside the front control panel of the Classic LX200; remove the four small screws and make SURE not to rub any of the wires against the metal base or they will discharge and damage the capacitors in the circuit board....you can also access the fuse by removing the bottom cover, which is what I would recommend.  The fuse is a 1 amp, slow burn and I bet it has blown. 

However, the reason it blew is because of your power source, I am almost certain.  So do NOT continue to use the same faulty power source.  Use only a Radio Shack or Pyramid 13.8 volt regulated system, or even the Wal Mart EverStart rechargeable jump start battery for your scope....NOT the Meade lump nor ANY power tank type of supply.

Dr. Clay

[pbyrne]

Hi all

Sorry for the confusion Dr Clay, it is a LX200 classiic, and it does work with the large hand controller box.

I will try your suggestion the fuse and about the alternative power source and pick up a 13.8 volt regulated system.

The powertank is a 12v system, it has worked in the field up to this, as has the current from the house, which makes me suspect that it is an internal problem.

Thanks for the replies people, and sorry that my first post is a post about a problem.

Paul

[lindendave]

Paul,

I apologize for not having welcomed you to the forums here at ASO so Welcome!

You have found the fountain of youth when it comes to expertise on the LX200 classic, well hey just about any telescope!

Welcome aboard!

[pbyrne]

Thanks for the welcome Dave and I certainly hope this is the fountain of youth for telescope troubles.

Paul

[pbyrne]

Hi Dr Clay

Are these the regulated system and jump start battery that you were talking about?

http://www.maplin.co.uk/13.8v-regulated-mains-power-units-231

http://www.maplin.co.uk/13.8v-regulated-mains-power-units-231

Thanks

Paul

[drclay]

HI Paul....
Thanks to Dave to alerting me to your question; I have been a bit on the busy side the past few days.
YES, those are excellent power supplies and far better than 18 volts alternatives.

Dr. Clay

[pbyrne]

Just realised that I entered the same product twice

The jump start battery would be this:

http://www.maplin.co.uk/search?criteria=jump+start+battery

Sorry for the confusion, that will teach me to read my repelies before I post them.

Paul

[drclay]

I am not convinced that this would be a good telescope battery, for the simple reason that it also includes at 100 psi "tire inflator".
Goodness, why in the world can't manufacturers just make somethings simple?

You might consider investing in a good marine battery and stand-alone Black and Decker (or similar) charger; a deep cell Marine battery will power your telescope for up to a week on a single charge, even if you used the scope all night long, every night of the week.

They would be difficult to carry around, but it would sure be better than taking a chance with these "Power Tank" sources.

I found out yesterday that I THINK that Wal Mart no longer carries the EverStart Jump Start unit....can anyone confirm?

Doc

[lindendave]

After digging through Walmart's site, and the extensive ads, I did not find the EverStart Jump Starter listed as a carried product. It appears as though the major brand they carry now is from Schumacher.

[Devon Oxford]

   I picked up one of the (Walmart) Schumacher PP-2200 batteries the other day...  2200 Peak Amps... 22 Ah 'Professional Grade' ... High Output AGM Battery. Just one 'cig lighter' plug, and two 400 watt 120V inverter plug-ins. No lights, radios, or even 'car jumper' cables... Ideal, if it works as advertised. This one spent a LONG time on the shelf, so I'm a bit concerned about it's overall health.
   I'm going to do some 'stress testing' on it (not on my mount yet) and measurements ... if things look good, I'll pass the word on...

       Devon

[pbyrne]

I was in my local hardware store this afternnon and I had a look a 13.8v regulator.  Can anyone tell me how it works?  How do I connect it so that the scope gets power?  With the ac adapter there is a connector to the scope that is connected to the adapter, in the regulator there is only the power cable for connecting to the mains and, where does the the connector to the scope go?

Seriously confused.

Paul

[drclay]

First of all...
Devon, thanks for the report on the newer Wal Mart power source.  That sounds like it will do the job.
Now, Paul.....
The connection to the scope can be made in many ways;  you must remember that the center pin on the scope connection is always POSTIVE and the outer sleeve is NEGATIVE....do not cross over, ever.

The plug for the telescope is a 2.5mm i.d., x 5.5mm o.d. "N" size plug that can be obtained at Radio Shack or similar.

Now, your power source will have some type of output; the one that you sent the link to had a red and black front alligator-jack type plugs on the front.  You can either use alligator clips by slipping inside those two holes OR you can actually find an adapter that will plug directly into the front holes of those connections.  Not only that, but the two knobs (red and black) will unscrew and you can simply wrap a bare wire around the terminal and screw the knobs back down firmly.

Be SURE to put an inline fuse in any power line going to the telescope....a 1 amp slow burn fuse is recommended.

Good luck...

Dr. Clay

[lindendave]

Paul,

I have some surplus parts along the lines Doc has suggested from my days of portability prior to the completion of my observatory. If you're interested you can send me a PM and I will dig through my boxes.