Nexstar 4 issues.

Helix · #1 16-03-2007, 04:39 PM

Hello,
I've just picked up a nexstar 4. I've been concentrating on the theory side of things for years, now its time to get some observing in.

I've been having some issues with this nexstar, frustrating, and making observing almost impossible. These problems are relating to the rs232 port and alignment.

1. alignment.
I can align ok using the quick align, however, as expected the alignment is out. So I have been trying the Auto Align and 2 Star Align.
With the Auto Align, I use the first star to align, easy, then I select the second star, go to it and do the alignment, but it fails - every time. Quite often if I cycle through the stars and select one that I have already tried it doesnt even move - for example, I tried to align to aldebaran then alpha centauri. After cycling through to alpha centauri a couple of times it didnt move from aldebaran. Ok, this is a bit of a cryptic explanation, but I hope you get the idea. So I then move the scope to alpha centauri (for example), do the align and it says Alignment Failed.
Same deal with 2 star align, it fails every time.
Its starting to get irritating because I am trying to get some good viewing in.
Any clues to what I am doing wrong?

2. RS232 cable. I bought the cable, but nothing, says cant communicate with telescope (Nexremote and Guidestar). I've tried two computers and still nothing. I am moderately computer literate (have quals in IT) so I doubt it is a pc problem.
Has anyone had a similar issue and how did they solve it. I have seen the pages on set up problems, none of them solve the issue.

Any advice on this from celestron/nexstar users would be greatly appreciated.

MikeyB (Michael) · #2 17-03-2007, 10:48 AM

Hi, Helix.

I use a NexStar 8i and am familiar with two star alignment only - my viewing area is narrow and I need to specify the alignment stars to be sure of them being visible.

Have you carefully followed ALL of the detailed steps of the text description of the Auto-align process? The Quick Setup photo guide omits crucial details. Personally, I found it difficult to follow your account of the actions you had tried, so it's impossible to know what steps are going wrong for you.

I'd suggest you use the two star alignment system - it allows more control of the process and you apparently know the stars already, so you won't be intimidated by having to pick a couple from a menu. The Celestron manuals get this alignment process wrong too - it is essential to update the current time and date whenever you commence an observing session. If your location hasn't changed since last time you entered it, the lat/long details will be preserved OK.

I'd strongly suggest using an external power source (those cheap car starter power packs are good), rather than 8 x AA cells. All GoTo scopes eat batteries and quickly become erratic and unreliable as the available power diminishes.

Cheers.

Karls48 (Karl) · #3 17-03-2007, 11:03 AM

There are many versions of NexStar and some of them got serious bugs. On early NexStar GT, RS232 does not work at all without modification. The time zones are not standard; you have to find number for your time zone in the manual. It took me some research and work to get my Tasco Starguide (NexStar GT) mount working satisfactory. Good Web site to learn about bugs and fixes is http://www.nexstarsite.com/index.html

Helix · #4 17-03-2007, 05:56 PM

I got it to align nicely last night with autoalign, I'm happy with that for now, I'll get going with 2 star align when I have some other bugs sorted.

As for the rs232 cable...seems that could be the problem, it is an early scope.

What modifications do you mean? (Karls48) I'd like to get this sucker up and going, I've poured through nexstar site and come up with nothing that stands out.
I dont think mine is even a GT, earlier than that (if that is possible).

Karls48 (Karl) · #5 20-03-2007, 06:25 PM

Sorry Helix, my Internet connection was down for few days.
On early models NexStar you have to modify hand controller (that’s what I did) or build simple RS232 interface. Then you use NexRemote to control your scope. Your scope is completely controlled by the computer using latest version of firmware. The modification has a switch that lets you to use the controller as before. It works well for me, even the tracking is much better.
http://www.dd1us.de/Downloads/remote%20controlling%20the%20nexsta rs%201_0.pdf
Please note that I’m using NexRemote , not the Guidestar