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CG5 mount with NexStar hand controller problem?

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#1 motorcycle jack

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Posted 19 March 2013 - 08:06 PM

I tried finding if there are any problems with the NexStar actually positioning on the correct stars when using the GoTo function. I didn't see much other than possible slippage. What I do is I set the mount up for use with the mount pointed at the celestial pole and try using two star or three star calibration. It seems the mount is all over the place when searching for stars that should be visible. And if I move to the star and enter the position as correct, it doesn't find the next one nor any objects I want to goto. I can't figure out what is going on. Is the software corrupt, mount funky (doesn't appear to be slipping or anything) or something else?

#2 Eddgie

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Posted 19 March 2013 - 09:08 PM

I would do a "Reset to factory Settings" and then re-initialize (enter time, date, and location like you did when you first got the mount).. Make sure you select daylight Savings time.

A factory reset usually fixes problems like this where the scope is behaving erratically.

#3 mclewis1

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Posted 19 March 2013 - 09:44 PM

How old is your mount?
Has it ever worked correctly?
What are you using to power the mount?

We'll assume that the clutches are snug and that there aren't any gross hardware problems.

1) Ed's suggestion about the Factory Settings reset is definitely a good place to start.

2) Power

3) Power ... no kidding. The most popular reasons for strange problems is power. An undersized 12v power supply or a battery that's starting to fail (not holding a full charge) will cause all sorts of strange problems. The mount needs a solid regulated 12v at 1.5 to 2amps (and more amperage is just fine). The power connection needs to be a 2.1mm x 5.5mm connector and not the similar looking 2.5mm connector that is often used on Meade products. The power switch can also cause problems. There were some bad switches on a few mounts where the internals of the switch would break down. You can try cycling the switch on/off over and over with the power off. If you find the switch is a bit flaky it's best to leave it in the on position and use the power plug to turn the mount on and off.

4) External connectors. Remove and clean the small connectors for the hand controller and for the DEC cable. You can use something like an old tooth brush on the connector side. For the socket side a paper towel folded tightly and dipped in a little alcohol or better yet real contact cleaner (available at places like Radio Shack if your in the US) works well.

5) Internal connectors. Only a last resort you may want to take a peek inside the mount and look at the connectors on the boards. Carefully removing the connector from the board and reattaching it can help clean off the connections. This is something you need to be careful doing but you can sometimes also find a loose connector or wire.

6) The rest of the possibilities are beyond the capabilities of most folks. Encoder problems affect the pointing accuracy and can sometimes be diagnosed by swapping motor/encoders between the RA and DEC axis. Board or component failures can sometimes be intermittent and not solid which will show up as "strange" pointing problems.

With good data input after the Factory Settings reset and good power and connections you should have all the fundamentals covered. Point the scope roughly at Polaris, do a two star alignment using well separated stars on one side of the meridian (you don't have to take the hand controller's default choices), add two to four calibration stars and you should be good for accuracy.

#4 motorcycle jack

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Posted 20 March 2013 - 01:23 PM

OK, thanks for the suggestions guys. I will do a factory reset and go from there. I bought it used so don't know how old it is (I think 3-4 years) nor if it ever worked. I have a good power supply (two truck batteries in parallel) so it will give 4-5 amps for hours, but will look at the connections. Hope I get it working soon, I hate star hopping all night.

#5 motorcycle jack

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Posted 20 March 2013 - 07:45 PM

Alright, did a reset and that didn't help so I went looking. I found corrosion in the connectors for the hand piece and the drive motors, don't know what cause it. Used some carborundum paper and a pencil eraser to clean and polish the connections - and SUCCESS! It now points very close and I did several calibration stars and it is right on. So thanks guys for the help and pointing me in the right direction.

#6 Fred1

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Posted 21 March 2013 - 03:04 PM

Congrats. I love my two CG5 mounts. Which is why I have 2.
I always do the 4 calibration stars, it seems to give superb GoTo accuracy and if you go through the Polar Alignment routine in the Hand Controller it tracks like a champ.
Highpoint Scientific supposedly has the last remaining stock and is selling them for $549 while the supply lasts.

#7 dragonslayer1

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Posted 27 March 2013 - 08:27 AM

Hey Fred, are you talking the ASPA thru handset? The CG-5 has that capability I was told by Celestron so no polar align scope needed?? Thanks
Kasey

#8 mclewis1

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Posted 27 March 2013 - 08:37 AM

Kasey,

For the vast majority of folks that is exactly the case - ASPA means there's no need for a polar alignment scope. For highly accurate polar alignment required for longer exposure imaging many folks will also perform the proven drift alignment procedure(s). This is also true for those using the polar alignment scope as well.

Some CG-5 owners do continue to use a polar alignment scope with good results but for most of us it's just not a necessity.

#9 dragonslayer1

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Posted 27 March 2013 - 09:13 AM

The number one brain trust, thank you so much Mark. M CG-5 should be here thursday. Will use it for portable (star parties, outreach, camping), Have my Orion 80 to mount on it for now. The CPC 9.25 wedge is just a little too much..
Kasey






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