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Nexstar 4-GT miss-alignment ? HELP!!

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#1 orion61

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Posted 27 October 2012 - 06:27 PM

Hi all I took on a project of repairing an old 4GT, it really is a cute little scope, I figured out the dissasembly
of the rear cap to get to the collimation Push-Pull screws,
that part is done.
But when aligning ONLY Auto Align is available no 2 star ect.
Is this right?
Also the Go-To is hit and miss on alignment, it sometimes will be totally off with every object wat off but consistant.
I replaced the Motor ctrl board and handset off a working one. I noticed the RA motor is coated on the screw adjustment area where the wires go and the encoder adjustment is.
I also saw the encoder is adjusted nearly all the way down where the encoder wheel is. should the encoder have the (tic) wheel centered or close like that.
I can tear a C8 and LX200 apart in my sleep but this is my first experience with one of these little "pea shooters"
(we will see how old you are if you ever had one of these LOL) !!
I found nothing on the NexStar resource site.. I think I've done everything except rpl the motors and encoders.
I'm ready to part the darn thing out. I'd like to get it running for my 9yr old Daughter.. or myself on cold nights when the 12" isn't worth the labor....
Any suggestions would be great.. I already have too much tied up in this thing...
clear skys
Larry

#2 Tel

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Posted 27 October 2012 - 07:03 PM

Hi Larry,

As far as I can see, (and it's getting late over here in the UK so I might not have all my wits about me), according to Mike Swanson's book, "The Nexstar User's Guide", the original 4GT could indeed only be aligned via the older "Auto Alignment" method when Alt.Az. mounted.

He intimates though, that an EQ North/South can also be carried out when the inbuilt wedge is brought into play but I have to admit I just haven't had time to read the details.

Additionally, he writes a section within his book in which he addresses "Common Problems with Alignment on the Nexstar 60/80/114/4" which may concern your attempts to align. Again though, I'm sorry but I haven't read the section in detail.

Finally he explains how the index marks should be approached when aligning. Apparently you need, (according to Mike), to "move the front of your 'scope UP to the index marks. Be precise" !

Best I can offer for the moment. I suggest if you don't already have Mike's book, your secure yourself a copy. Otherwise, let me know if I'm on the right track and I'll try to precis the information for you tomorrow !

Best regards,
Tel

#3 Tel

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Posted 28 October 2012 - 03:59 AM

A few more thoughts following a little research this morning, Larry.

You say, "Also the GoTo is hit and miss on alignment; it sometimes will be totally off with every object, way off but consistent".

This suggests to me that at other times the GoTos ARE accurate or relatively so indicating a procedural error rather than an/electronic/mechanical cause. In other words, perhaps it's only consistency of the alignment procedure which needs accurising ?

Secondly, you said that you didn't find Mike Swanson's Nexstar Resource Site particularly helpful in this instance but did you come across this entry ?

http://www.nexstarsi...entProblems.htm

(See in particular bullet point 3).


Finally of possible relevancy, it might help to know which HC version you are using.

Hoping this helps a little further.

Best regards,
Tel

#4 orion61

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Posted 28 October 2012 - 04:36 PM

I don't know what software version it is, just says 4" and press enter then goes to auto align, there are no other options. this isn't the 1st version it is the GT version.
Has me totally perplexed. some times after alignment it will tell me Mars is low South!
sometimes the 2nd alignment star will be totally off even pointed to the ground.???
I thank you very much for taking the time to help me. I am usually pretty good at computer gadgets, I am A+ certiified,
worked for 5 yrs for a Major American computer company phone work, support.
I have a NexStar 6se that is a Diamond and a 127 Mak Slt. My mount is DEAD on, where others have had trouble. I put a taller and more Beefy Tripod and it is solid as a rock,
Also 2 LX200's one with the updated Autostar..
I had one of the first NexStar 5's it worked great!
I am about ready to junk this thing. I have a trade for an old N4 mount for an LX6 Meade in the basement, so I think I will try new motors and encoders, If that doesn't work it is going to be Scrap the N4 Clyde....
It is a cute little bugger, and handy.. but I have too many scopes... If you ever get the chance on a 127 Grab it!
It performs right with my 102 APO refractor!!
I think they will be a Classic now that they are out of production.
You should take a look at my post in Cats and Casses on the 127 making it more stable.
Anyway I thank you much.. During this time of year it is Cloudy, if it isnt cloudy it's raining, if not raining Foggy.
You get the hint..
Take care my friend. Larry

#5 Tel

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Posted 28 October 2012 - 06:40 PM

Hi Larry,

Assuming you've established and are sure your HC is therefore an original, (?) have you then followed that procedure for entering the appropriate encoder number, used the correct index marks approach, applied the right centralisation directions for alignment stars in the EP etc. under bullet point three of Mike Swanson's "problem page " above ? In other words, are you convinced that you are folowing the correct alignment procedure to the letter for this particular 'scope detailed in MS's book ?

Please don't get the impression I'm trying to teach my grandmother to suck eggs here as you're obviously well versed in this "black art", but If you're in any doubt over any of the issues I've glossed over, I'd suggest you at least review these apparent "necessaries" before writing off all the good work you've already put into getting this little 'scope functioning satisfactorily.

Best regards,
Tel

#6 Midnight Dan

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Posted 29 October 2012 - 06:26 AM

Hi Larry:

Not sure if that scope allows firmware updates, but if it does I'd suggest re-flashing the latest firmware from the Celestron site.

-Dan

#7 orion61

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Posted 29 October 2012 - 08:53 AM

My hand controller is the early version that cannot be flashed.
I have tried the custom and entered the correct encoder info. I have tried 2 hand controllers.
I have leveled and used a compass, also lined up on Polaris then leveled the tube from there.
It some times it seems fine other times it looses its mind and goes crazy, I havent had it long but have been very limited useing it outside because I'm just coming off surgery to take my rpl knee hardware out and packing it with antibiotics for MRSA Staff infections. but I am running my MexStar 6se right by its side.. now last night it aligned ok and I let it run all night on Jupiter, tracked fairly well. I did rpl the motor control board.
I'm about ready to junk it cause its not worth the frustration. I wanted something simple for my 9 yr old to get started with, that would be easy. she already has a Jason Comet Chaser she uses and likes. I was surpeised that for the design it performed as well as it does.
I thank you very much for your help.

#8 Tel

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Posted 29 October 2012 - 12:45 PM

Some times it seems fine other times it looses its mind and goes crazy.



The inevitable question in view of the above !

Are you certain your power supply is reliable ? :idea:

Best regards,
Tel

#9 orion61

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Posted 29 October 2012 - 01:11 PM

Some times it seems fine other times it looses its mind and goes crazy.



The inevitable question in view of the above !
[By the way I like that little lightbulb Graemlin.....
Are you certain your power supply is reliable ? :idea:

Best regards,
Tel


color:"blue"] [/color]
Tel your Inductive reasoning is a thing of beauty.. alas that is not the problem, :foreheadslap:
I have the A/c adapter and my portable 12v Power supply,
A kids electric Barbie car battery rewired for my LX200 12"
I found the problem!!! while I had it partly torn down and cleaning components (encoders) I accidentally bumped a wire
that was gummed up with the blob of clear silicone they put there. the mount stopped tracking and had to be rebooted.
Once I had the system up again I pulled on each wire with my tweezer pliers, when I hit the red one it did the same thing. A quick cleaning of the Silicone and resolder on the encoder and now the little guy is tracking like a charm!
All this time, the handset, motor control board , AARRGH
(Thanks Charley Brown), and it was a simple wire.
Off Subject, Tal, who do you and your fellow friends want to win in the American Presidential race? Or do you care.....
Thank you ALL for the help, I think I will Haunt these forums for a bit and learn some......
Larry


#10 Tel

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Posted 29 October 2012 - 01:52 PM

Many thanks for the compliment ! :bow: I'm glad the problem had a simple fix ! :waytogo:

As to your forthcoming presidential elections, I'm not permitted to comment under CNs rules and, even if permissible, my political leanings would be irrelevant.


I don't have a vote ! :rofl2:

Best regards and congratulations on a "good result" !
Tel

#11 Midnight Dan

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Posted 29 October 2012 - 01:58 PM

Hi Larry:

Seems like your persistence paid off! Good sleuthing! :bow:

-Dan






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