LX200 Scope Woes....any ideas?

[Rodstar]

I am having some dramas with my LX200. I am going to drop off the scope to Bintel next weekend to see what can be done.

What's wrong? I first noticed a problem a week and a half ago when I was half way through an observing session in my backyard, after about 90 minutes of normal observing. I had the scope hooked up to a Power Pack (fully charged), via a **** Smith DC to DC adaptor (the sort that has a cigarette plug at one end and attachment to the 12V DC in-port at the other end). Suddenly, without warning or explanation, the power cut out. It was not a dewy night.

Last weekend, I took the DC to DC adaptor to Repco, and with their help I changed the fuse in the DC to DC adaptor, which had blown. When I put the adaptor in the power pack, the operating light went on the adaptor as is usual, but as soon as I then connected that to the scope and turned the scope on, the fuse blew again instantly. As I have two power packs (identical), and supposing that there might be a problem with the power pack, I tried the same process (with a new fuse) on the other power pack. Same result: blown fuse. I went through three fuses in this way, without getting the scope to work at all.

I went back to Repco yesterday, and they agreed with me it was not the power pack(s). It must be either the adaptor or the scope. In order to eliminate the adaptor as a possible cause, we agreed that I should buy batteries for the forks of the scope, and test the scope's performance with that power source.

I therefore purchased 8 brand new C cell batteries for the forks yesterday, and tried using that power source last night at Kulnura. Although the scope turned on and at first appeared OK, during the alignment process I noticed that the the movements of the scope were very lethargic, and the keypad was not lighting up fully as I had been previously accustomed to. Then, within 5 minutes of alignment, the scope started beeping every 20 seconds or so, which I understand is an indicator that the batteries are low. Within another 5 minutes, I began to hear hissing/ gurgling sounds coming from the computer part of the scope at the base of the fork. I turned the scope off immediately, and only used it as a push-to for the rest of last night.

I am satisfied that the problem is in the computer of the scope itself, and not in the power pack or connections. It would appear that the scope is drawing far too much power, and that this is blowing the fuse on the DC adaptor, and overheating the scope.

In terms of the history of storage and use of the scope, when not in use it is stored in the set up position on its tripod in the study of my home, which is at a constant temp. of 24.5 degrees (ducted air). I use the scope between 1 and 3 times per week, mainly in my backyard, but once per month take it up to Kulnura. Whenever I transport the scope, I take it in its original box (with foam). I has always been treated with the upmost tender loving care, and never shown any problems before. I am not aware of any dew getting into the scope: the last two weekends have been almost completely dew free. The way that I store my scope means that if there had been any dew settle in the scope before, I would have thought it would have dried out.

Any ideas or similar experiences???? :confuse3:

Maybe I shouldn't have sold that 12"Dob!!!! :scared2:

[h0ughy]

sounds like the motherboard has a short,or one of the motors, similar thing happened to me, i went through 3 motherboards, thank goodness for warranty. it will always run sluggish on batteries. get it to bintel asap, only 4 weeks left until spsp.

[xstream]

I agree with what Dave said Rod.
Motherboard or motors shorting.
Good luck, I hope you have it back before SPSP.

[stinky]

Hissing - or gurgling? Sounds like a defective eletrolytic capacitor. Since manufacturing in China lots of boards use low quality and close to operational tolerance capacitors. Unfortunetly modt people just board change instead of replacing the cap'. (The caps' are used for power supply smoothing amongst other things.)

IF it is a failing cap - you can usually spot it by bulging / popped ends.

[Rodstar]

Thanks for the suggestions, guys. Not being very technically-minded, I have no idea what an "electrolytic capacitor" is? Is it like a flux capacitor? :confuse3: :lol:

[[1ponders]]

Hi Rod, while not the same thing I had something similar occassionally with my old 8". On a couple of nights I turned the scope off (you know when you do a slew and forget you've got a toUcam in a barlow or a 300D attached :scared: ) and turned it back on the fuse in the lighter attachment would blow. I soon realised what was going on and made sure I waited a while for the scope and wires to cool and reduce ????"resistance"???? and no problem. But now reading your problems I wonder if it's not an inherant problem and that my situation wasn't as bad as others.

Not much help sorry, but at least you know that your situation isnt unusual. Maybe meade need to get their act together on this if it is such a common problem. And while their at it they could fix the problem of if you put the batteries in the wrong way you can do damage. That shouldn't be able to happen. Either putting batteries in the wrong way or if you do it shouldn't be able to do damage. A warning in the manual is not enough.

[acropolite]

As stinky said could be a capacitor, in fact a large proportion of faults in electronic equipment are caused by faulty capacitors. That said the caps in your electronics may be surface mount types which will be difficult to replace, even if you can identify which one is faulty. FWIW capacitors have a finite life, anywhere from 5,000 to 50,000 hours and tend to last longest with power continuosly applied. Often when they fail they will destroy other components with them, so the hissing and gurgling may well be a very bad omen. Rod, an electrolytic capacitor is one that has an electrolyte between it's plates, usually a gel which enables it to have larger capacity. Here's some light reading for you... http://en.wikipedia.org/wiki/Electrolytic_capacitor#Construction :)

[RB]

Similar to a Class Action Lawsuite Rod........:P

[Rodstar]

Thanks for that link Phil, but it is all double dutch to me!

Andrew, so long as I can sue someone, it can't be too bad!

As I was posting, my wife said she could hear a noise coming from my scope. I just opened the battery section in the forks to find one of the batteries leaking. Clearly what I heard hissing and gurgling was the battery. I have tried to mop up what I can of the battery acid. Probably in total I mopped up about 1/20 of 1ml, a tiny amount. I cannot tell if any has gone into the body of the scope, but it doesn't look like it. Fingers crossed.

[RB]

I've got a funny fealing it wasn't the battery you could hear Rod.
I think Phil is right about the capacitor.
You did the right thing though in cleaning out the spill.

I'm sure Don at Bintel will have you up and away in no time.

:prey:

[Rodstar]

I just came across the following excerpt from an LX200 forum in the US...

Quote one:
"The scope was originally introduced as 12v and, as the story goes, upped it to 18v to out slew the announced Celestron goto scope. The
motherboard still gets the same stepped down voltage, 5?, as before. For more, visit the Mapug Topical Archive--> Battery, Volts, Amps, Etc. at the link below. "

Quote 2 in reply:
"In this case, "as the story goes" is not correct. The slew rates are controlled by the computer through generation of drive pulses delivered by it to the drive circuitry. The scope slews at the same rate as requested by the hand keypad regardless of the voltage.

The reason that the voltage was raised is that given earlier by Mr Ware. It is very hard on the motors to have them stall. They can then overheat and/or the transistor drivers can burn out.

With the higher voltage on the drive motors, they are not as likely to bind and stall and thus they become more reliable. When they do stall however, the dissipation gets very high. Thus at an even later date, Meade has installed current limiting resistors to protect the motors and the transistor amplifiers.

The telescope will run well on 12 volts so long as the axes are not biding and the telescope is well balanced. In many LXs however, the slow speed focus will not work with voltages near 12 volts. There is a marginal design here. Thus on some the focus works and on some not.

For some years now Meade has advised that 18 volts be used for the reasons stated above.

Doc G.

I am wondering if my 12v Supa Cheap Auto power packs have not been up to the challenge, and maybe this has contributed to any damage?. Those who know my observing style will know that I often have a pretty ambitious list of objects, and often do 50+ on a good night.

Does anyone on the forum run their LX200 on 18v?

[Hitchhiker]

Hi Rodstar - my understanding is that the 'classic' LX200 runs on 18V. The LX200 GPS runs on 12 volts.

[Rodstar]

Thanks for that Adam....yeah, I read some more US forums, and that seems to be the go. Some threads indicate though that 15v works well on the GPS model because 12 volt leads often only actually deliver 10v or 11v, which is really not enough, and can cause problems.

[Rodstar]

Some good news. I dropped into Bintel today. Had a very reassuring chat with Don Whiteman, who has most of the necessary parts in stock for what needs to be done. Also, it should all be covered under the warranty...Phew!

I can't say enough good things about Bintel.

[RB]

Did he say what might be the prob, is it the 1.1 giga watt flux capacitor?

[Rodstar]

He's going to run a complete check on the whole shebang, he wasn't sure, but thought it sounds like something easily fixed.

Hopefully it can be fixed, and I can get Back to the Future!

[Rodstar]

I am pleased to report that my little 10" LX200 baby is back home after some repairs with Uncle Don (Whiteman). I haven't taken her outside to stretch her forks, but when I switched her on in the study for a quick check, all sounded hummingly reassuring.

Don updated the software to Version 4.0, and tidied her up generally. The corrector plate has never looked so clean! He also cleaned up a whole lot of battery acid goop from the forks.

The cause of the problems is a bit of a mystery. Don couldnt find anything electronic-wise that was wrong. I have replaced the DC adaptor, and am using the battery pack again. Seems that maybe the Dc adaptor was at fault after all, and the battery leak may have been a freak co-incidence due to a bad battery.

Looking forward to taking her out to SPSP14!!!

[RB]

Great news Rod.
Don's a legend.

:thumbsup:

[h0ughy]

look forward to seing the beast at work again Rod

[Rodstar]

Thanks guys. Yeah, hoping for some suckers in the sky tonight.