Possible problem with my new scope

[Athena]

Hello everybody

I have recently bought myself a new telescope, Celestron NexStar 8 SE.

Generally I am very pleased with this instrument, Friday night was my first real test drive and I was very impressed when I first looked at Mizar, seeing both Mizar A and B was awe-inspiring.

However, I think I might have a problem with it. After running "Sky Align" all seems to be good but shortly after the alignment seems to drift and the scope with slew to the zenith and almost jam against the mount.

Anybody else seen this behaviour?

Thanks

Nikki

[Mikea]

Hi Nikki, I don't have the same scope, but my Skywatcher GOTO used to do funny things when I first got it. You should first check that the batteries are all good, as low voltage seems to upset the system. I assume you can get the "Alignment Successful" message and then correctly slew to another object? The other thing I always do now, at the end of a session, is to "PARK" the scope so that it is (very) approximately aligned next time Mr Cloud has disappeared.

[durr]

Nikki, try one of these and dump the batteries, the batteries are not up to the task and should be used as a backup only. Congratulations on choosing an excellent telescope. Have you tried cloudy nights forum? They have a nexstar forum with lots of people who know this telescope inside out. Steve.

Power

[rikyuu]

hi Nikki,

I had a similar problem with my first scope which was a Nexstar 60 SLT, although at the time, I sent it back, I now believe it was due to the batteries. I have another SLT now and when the batteries get low (in a very, very short time), it goes bonkers. Never had a problem running of a large power pack

[Athena]

Yes, power would make sense. Sometimes the batteries don't make contact properly and I have to open the hatch and wiggle them about a bit.

I have been thinking about making a cable and using a spare car battery which I have sitting in my shed. I believe that the power socket is 12v centre positive. All I would need is the correct plug, length of cable, fuse and some crocodile clips.

Would this be safe to the NexStar electronics?

Thanks

Nikki

[rawhead]

I use something very similar to this for my SLT:

Rolson 12v Jump Start with Air Compressor £24.99

Got mine from Maplins...

[brianb]

I have been thinking about making a cable and using a spare car battery which I have sitting in my shed. I believe that the power socket is 12v centre positive. All I would need is the correct plug, length of cable, fuse and some crocodile clips.

Would this be safe to the NexStar electronics?

Yes but there is no reverse polarity protection in the scope - suggest a heavy duty diode in the lead plus a 3A fuse.

You may also be having a balance issue, this is unlikely unless you're using a 2" diagonal and a heavy eyepiece or camera but it is possible that the altitude clutch could be a bit on the loose side. If it's a new scope you should consult your supplier before attempting to adjust.

[Athena]

I have just spoken to a chap called Steve at Telescope Planet (the place where I bought my scope)

He thinks that I might have a fault with either the mount or the hand-held control unit, but before replacing it, he is sending me a mains transformer. I will test using the external power supply.

I can highly recommend Telescope Planet to anybody wanting to by new kit. They are both extremely knowledgeable and very helpful.

Nikki

[Athena]

Hi have just spoken to a few guys over at cloudy nights and they all agree that it's a power related issue. Think I'll test with the mains transformer and see how it goes.

Many thanks

Nikki

[Astro_Baby]

Probably a bit late - I have Nexstar 4SE which is similar in operation to yours. Mine has never played up with internal batteries but I use VERY powerful AA batteries and only use them for short sessions. Low battery powery is most likely the problem as the Nexstars can be a bit stroppy about power (as can most GoTo mounts). I have external battery tanks and leads for my other scope and longer sessions with the Nexstar if needed.

I'd not use croc clips cos they often dont give a really good contact. Ok when you have 30amps running through them for a car, less so when you only have a small amp load.

So long as your off a 12v battery with the correct lead polarity you should be ok.

Ohhh something else - the Nexstar 4 power socket is a bit wonky. I had to open up the end of the power connectir pin with a small knife as the centre pic is a bit too thin even for Celestrons own supplied lead - could that be causing you problems.

[Taff]

Hi Nikki' my mate had a same prob with is GOTO scope.Found out that his batts was on the way out,but when he put the elec adapter to his scope every thing was working fine.Mark

[johninderby]

While it sounds like a power supply problem there is another possibility. I had an 8SE that had a similar problem when I first got it and I was going to return it but I had the chance to try another HC and it worked perfectly with the borrwed HC.

I updated the firmware in the original HC even though it already had the latest version and after updating it worked perfectly, no further problems so you might try updating your HC firmware.

John

[Athena]

Thanks again everyone.

I was considering flashing the hand control, I've not yet read about the procedure but suspect is as simple as connecting using the RS232 cable and running a executable.

Re: crock clips - I had not considered that possibility, maybe something more substantial like great big bolts?

I also like the suggestion form BrianB regarding placing a diode in-line to protect the system against accidental reverse polarity.

Great forum everyone, nice place to hangout

Nikki

[brianb]

I'd not use croc clips cos they often dont give a really good contact. Ok when you have 30amps running through them for a car

Actually it's precisely when you do have a massive current flowing that you really need a good contact. (Not that 30 amps would get you very far with a car starter motor anyway, most modern cars draw upwards of 80 amps to run the starter motor!)

Croc clips with serrated teeth are excellent, they bite into the soft terminals on the battery and provide an almost perfect low resistance contact. They're exactly what I use to tap power from my deep cycle leisure battery.

[sxinias]

I have a SkyWatcher Synscan AZ got mount. It is a NexStar clone. I think your porblem is most likely your batteries.

However, my mount once did some screwy things. The problem was the hand controller cable. While it made a resounding click when I plugged it in, it actually was not plugged in all the way. Once the cable was firmly seated the problem went away.

Unless you wish to spend a small fortune buying AA batteries, I'd get another power source.

I'd be vrey liery using an automobile battery unless you find some way that could prevent a nasty accident (reverse polarity). Seems to me it would be easy to reverse polarity in the dark of night as its easy enough to do it in the light of day.

Someone mentioned an automotive powerr pack. They are cheap to buy, 30 euros here in Greece, provide a solid power source, are easy to carry around, are essentially the same as Celestrons power pack, and it would be difficult to accidently reverse polarity with it. Also, handy to have if you ever do have a problem with your car.

Joe

Sxinias Greece

Meade 2090AT refractor

Meade 2045 LX3 SCT

Celestron C6S SCT

Meade DS2000 GOTO Mount

SkyWatcher SynScan AZ GOTO Mount

Celestron CG5 Mount with iOptron GOTO

one automotive power pack

[Athena]

Just to left everyone know that my scope is now fine

It was, as so many people have suggested, a bad power source. I tested my scope last night using a 12v mains transformer and to my joy everything worked really well.

I must say that I am very impressed precise goto, using it I was able to find M13 and M57 without any problems

Regards

A very happy Nikki