Our NexStar SLT has a mind of its own - Please Help

[Stewpot407]

We haven't had our Nexstar 127 MAK for long and in fact tonight is its first outing. Its set up on the patio nice and level. About an hour ago had our first viewings of the moon...wow!!! Mighty impressive even woke my son up to have a look (he's 10 and just wanted to go back to bed lol ).

Put him back to bed and tried to set up the alignment for my own viewing pleasure... I've set the time (2305hrs) date (05/24/12), city (set to London even though we're south of Guildford in Hampshire), time zone (4) and to 'day light hours'. So far so good. Time to align with the starts...I picked 3 bright ones and all was well. The scope gave me the thumbs up with a 'Align Successful'. Trouble started when I wanted to have another look at the moon before it disappeared. As soon as I touched the control pad the scope started to move...getting a bit excited now....hand on. the scope went passed the moon and pointed towards the ground It then changed direction but ended up rubbing itself against the tripod. In panic I started to pressed buttons to stop it. Nothing worked and the scope continued to push against the tripod. I had to hit the power button to make it stop.

Not willing to give up I followed the instructions again only this time the scope just set off by itself (after the alignment was successful) and hit the tripod again.

What have I done wrong?

Heeelp!!!

Cheers

Stew

[sgazer]

I wish I'd asked this question on the forum when I first got my SLT and thought it was faulty and sent it back, only to have to buy another one a couple of years later after finding what the problem was (at greater cost). Hopefully yours is the same issue;

Are you using AA batteries? Are they rechargeable? Using AA's with this mount is hopeless (rechargeable even worse as they are lower voltage). It makes them start to go flat within minutes and it seems to need a high voltage to make it work properly otherwise you get the symptoms you mention. I would try a 12v regulated power supply, at least 2amps or a larger 12v battery, eg. a sealed one. Hopefully it'll be ok then.

Ps, if you have a DSLR and lens, I highly recommend making a little L shaped bracket with a dove tail (or you can buy them) and taking a few 20-30s exposures, ISO1600. I'm sure you'll love the results!

[garethmob]

another mention, did you put it back into park mode after you did allignment, or did you leave it where it was and carried on? if left it where it is sometimes it can become finiky and think where it is is home, carry on and crash into somthing

also the 12v power pack is a good idea!

[Stewpot407]

I had a thought of power being an issue but I'm using a tried and tested 12v power pack. Fully charged and able to start a car

Its just so frustrating, I can't follow the instructions any closer

gutted

[sgazer]

I was hoping that was the problem. It sounds like you've done everything right as you've got a successful 3 star alignment, which isn't easy in itself. Try experimenting; see how accurate it is going to objects within the triangle of stars you've aligned on and then try going further a field to see when it falls over. Also try re-syncing on an object further away and see if that helps. This issue does sound strange though as normally if you'd done anything wrong the 3 star align wouldn't be successful.

[Steve Ward]

Timezone 4 puts you in Moscow or Dubai , could be the problem ?

[sgazer]

Timezone 4 puts you in Moscow or Dubai , could be the problem ?

oooo yes, well spotted, that's not right and would explain why the slew went past the moon into the ground if it was setting. The scope was 3 (4?) hours ahead of where it should be (check the manual last page. Strange the align worked though.

[Steve Ward]

UK is timezone 0 (+1 at moment) , I still forget the BST offset now and again .

[CFC]

Only asking, mine is a Nexstar and we set it to Universal Time and then summer time...what is the 'time zone 4' on the SLT?

OOps just seen post above - that time zone will be the issue then!

[JamesM]

With Synscan (Skywatcher) Goto systems, there exists on the handset an 'ESC' or escape button that will immediately can cancel any instruction and in the process any movement that the mount in making. I notice that this button doesn't exist for your handset, only an ''UNDO" button which according to the instructions simply takes you back though the menu choices and cancelling any input you might have made. I mention this because I don't want you to start damaging your new kit. Does the 'undo' button stop the motors?

I am not familiar with your setup but having looked through the 'Sky Align' procedure, it looks as if you have followed the instructions correctly (date, time zone etc) but the problem might be in your choice of stars. When making your choice, (I'm assuming most goto systems work in the same way here) you should ensure that one star sits in the opposite half of the sky as the other two choices. This dividing line is called the 'meridian' and is a line that runs from north to south. The two stars that will inevitably occupy the same half of the sky, should be well apart form each other. I would also pick stars that are at least 30-40 degrees up in the sky as that helps too. That's my only suggestion for now but will monitor the thread to see how you are getting along.

James

[Stewpot407]

Stupid, Stupid me!!!!

I looked at the timezone map at the back of the manual and found the kids drawing of the UK with a number 4 in it.... you know, the Uk to the left of Kazakhstan! Best I not tell the wife about that one.

@James, The hand controller has no button to stop the motors from running. The only options I had were to either press the opposite direction button but as soon as you let go of the button the scope would revert to rubbing the tripod or to disconnect the power.

Cheers

Stew

[JamesM]

That seems a little bit daft - you should have the means to terminate a directional instruction as you have already found out. So you have input universal time zone and has it worked out or will you be trying that out on another night.

James

[sgazer]

Stupid, Stupid me!!!!

I looked at the timezone map at the back of the manual and found the kids drawing of the UK with a number 4 in it.... you know, the Uk to the left of Kazakhstan! Best I not tell the wife about that one.

Cheers

Stew

LOL, absolute classic! I have lots I could blame the kids for too, but mostly it's the wife's fault!

[Cath]

On my Nexstar 6SE to stop it moving to any object you push (and release) any one of the 4 larger manual move buttons - up, down, left or right.

And yes, I do the same with the time zone - set it to UTC (same as GMT) and use summer time setting.

[Stewpot407]

argh! Its off again.

Aligned it again using the correct time zone this time and as soon as I confirm the settings the scope just flies off at a tangent and none of the buttons can stop the motors from running. I'm going to video it. I must be doing something wrong but I just dont know what

Cheers

Stew

[Stewpot407]

Going to have to give up and send it back. Wife has been with me reading out the instructions....3 brightest stars aligned, scope confirms this and then moves off and tries to kill itself against the tripod. None of the buttons will stop this apart from turning off the whole setup........gutted!

[JamesM]

Stew, is there a home position that you return the scope too? On the Synscan goto system, you have to 'park' the scope back to the home position because it will know where to start from when you next use it. I'll go back through the instruction manual to see if I can spot something you may have missed. I have had a look through past threads and the only suggestion there is power supply. Just to double check, is there any other power source you can use for the initial aligning setup that would help confirm for sure that the existing power pack is working properly?

James

[JamesM]

Stew, you might want to watch

video. Although it is a video for the SE Nexstar product range, I thought it might be useful for you as it uses the same Sky Align 3 star alignment procedure that I believe is the same as employed in your scope. The instructions commence at 3:26 in the video.

James

[Stewpot407]

Hi James,

I don't get time to react to the scope, as soon as 'it' says alignment successful it just takes over and does its own thing. There's no park or return option that I can find. The only thing I can do is guide the scope from the tripod by holding down the direction arrows. The scope will then move in that direction to safety. As soon as I let go of the direction buttons the scope reverts back to its own mission.

[JamesM]

I have found this past thread which you might want to look through as it seems this person has had a similar problem to you. Could also send him a PM to get his take on what the trouble was.

James

p.s Whilst looking around for resources for you, I cam across a dedicated Celestron Nexstar section on the U.S Cloudy Nights forum here. you might want to spend some time having a look through some past posts to see if others have experienced the same problem. The general consensus I am picking up through looking around on the internet is that the 3 star alignment is problematic as others have expressed similar problems.

[Stewpot407]

Just watched the vid and I do exactly the same as the poor chap in the vid.

The only difference is that their button says undo and mine says back.

[JamesM]

Stew have a look at the above link at the bottom of my post (I've been editing while you have been watching videos! )

James

[johninderby]

I had a Nexstar once that had an alignment problem that I could'nt solve, and I was about to return it, but decided to try one last thing. I updated the HC firmware even though it was already the latest version. After that the mount behaved itself. Problem solved.

Might not help your problem but it might be worth a try.

John

[Stewpot407]

Thanks James, as you can probably tell I'm very new to all of this. That said, if you want to know about racing a Lotus Elise give me a nod

i'll check out the link in your thread.

Thanks again

Stew