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Need advice before buying Celestron CG5 AS-GT.

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#1 Mitch Hamilton

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Posted 06 February 2014 - 09:06 PM

So I'm looking at an ad for a used Celestron CG-5 AS-GT computerized mount and the price is VERY good, but I'm just concerned that it's for a problem that will put me down a tough road. The ad indicates that the price is so low due to:

"an error code that says the hand controller has lost communication with one of the drives on the mount. I think it is the declination axis, because the mount slews non-stop in declination when I try to do a polar alignment."

My question is will this mount be a money pit? I am tech savvy and I have a fair grasp of electronics but are these mounts generally serviceable by an individual or am I going to end up having to send it in to Celestron at my expense?

Realistically speaking I don't have a budget for a new mount but if I don't go with this mount I'll probably save up money for another year and get the Celestron Advanced VX mount.

What should I do?

Thanks so much,

Mitch :question:

#2 jrcrilly

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Posted 06 February 2014 - 09:25 PM

That's usually caused by a bad encoder, which is part of the motor assembly. That wasn't too bad in the past (the motor assy used to sell for $29) but I think the current price is more like $150. If it isn't the encoder it's probably the motor control board which costs at least that much. Or you could hit the lottery and it's just a bad connection between the board and the motor and you can fix it for free. I believe that's the least common situation.

#3 Stelios

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Posted 06 February 2014 - 10:02 PM

Don't borrow trouble. If you were buying it as a potential extra mount and a fun project that would be one thing, but if you're buying because you are short of money, wait and get the AVX.

1) The AVX is a superior mount.

2) Even if you can fix the problem of the CG-5, you have no guarantee that that's the *only* problem with that CG-5. You could get into a chain of problems, and be spending money to fix every one.

3) And if you fix everything, you have a used mount that, realistically, will not live forever (I'm not down on CG-5's at all--I own one, love it, it's my only mount, and it's been working fine for 11 years. But I wouldn't spend more than $325 or so to buy my mount today--and mine *works*).

#4 RTLR 12

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Posted 06 February 2014 - 10:03 PM

The error code means there is no communication between the hand controller and the DEC motor. Remove the lower plastic motor cover and look at the 4 connectors on the MC board. The 2 connectors marked "ALT" and "AZM" are for the motors. Swap the 2 connectors and re-test the mount. If the DEC motor continues to run non stop, then you have a bad MC board, but if the RA motor now runs on and on, then you have a bad motor encoder.

The MC board ruins $107 and a new motor runs $132.

Stan

#5 Mitch Hamilton

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Posted 06 February 2014 - 10:19 PM

To give financial context the asking price for the mount is $150. I'm still considering it for a "project" but all of your advice has made me quite weary.

#6 dragonslayer1

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Posted 06 February 2014 - 10:35 PM

Listen to Stan, he has 5 of them :bow:, Kasey

#7 jrcrilly

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Posted 06 February 2014 - 10:40 PM

Swap the 2 connectors and re-test the mount. If the DEC motor continues to run non stop, then you have a bad MC board, but if the RA motor now runs on and on, then you have a bad motor encoder.


If he buys it, that's how to diagnose it - but I believe you have the symptoms backwards. If the dec motor continues to run away when connected to the RA output the dec motor is bad. If the RA motor runs away when connected to the dec output then the MC is bad.

#8 dragonslayer1

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Posted 06 February 2014 - 10:47 PM

Also check the handset if its Nextstar+, I believe the ASGT should come with that model, Kasey

#9 RTLR 12

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Posted 06 February 2014 - 10:48 PM

John,

You're right. I was in a hurry when typing and misspoke. Thanks for the correction.

Stan

#10 Falcon-

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Posted 06 February 2014 - 10:55 PM

Well I am thinking if you have worst case of $132 for a motor added to $150 for the mount itself you have a CG5 for less then $300. Given it may be just a cable you may be able to get away with a CG5 for as little as $175 or so total.

At $300 a good working CG5 is a good deal, at $175 it would be amazing.

So if, and only if, the prospect of it being a bit of a work-to-be-done project is fine with you then it sounds like a reasonable deal to me! If the prospect of work/gamble give you an even slight hesitation though the AVX is indeed a slightly better mount and includes no "if" factor.

The one thing that would give me pause is if it is an early CG5 with the version 3.x handset instead of a version 4.x handset. The 4.x models can have their firmware updated, the 3.x ones can not, the 4.x ones have the All Star Polar Alignment feature, the 3.x ones do not.

#11 dragonslayer1

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Posted 06 February 2014 - 11:06 PM

I have a CG-5 ASGT and its really a good mount, Kasey

#12 jrcrilly

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Posted 06 February 2014 - 11:09 PM

I have a CG-5 ASGT and its really a good mount, Kasey


I've owned a couple. They are a very good value. Had to replace a motor in one, and had to bypass the power switch on the other. Such failures don't appear to be all that common; I wouldn't be afraid to buy another one.

#13 rmollise

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Posted 07 February 2014 - 10:56 AM

That's usually caused by a bad encoder, which is part of the motor assembly. That wasn't too bad in the past (the motor assy used to sell for $29) but I think the current price is more like $150. If it isn't the encoder it's probably the motor control board which costs at least that much. Or you could hit the lottery and it's just a bad connection between the board and the motor and you can fix it for free. I believe that's the least common situation.


OR...it could simply be a bad declination cable. However, unless you are willing to deal with it, don't buy a mount with known problems. OTOH, while the mounts can have encoder and other problems, most of the problems are pretty simple and relate to poor and dirty connections and poor power. ;)

#14 rmollise

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Posted 07 February 2014 - 10:57 AM

Also check the handset if its Nextstar+, I believe the ASGT should come with that model, Kasey


Only, perhaps, if it were one of the last ones sold.

#15 jrcrilly

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Posted 07 February 2014 - 11:06 AM

OR...it could simply be a bad declination cable. )


That would count as a bad connection between the MC and motor as mentioned above. I haven't seen one, though. Just a bad motor.

#16 Mitch Hamilton

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Posted 07 February 2014 - 03:02 PM

This is the hand controller he has on the ad.

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#17 steveor

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Posted 07 February 2014 - 03:44 PM

I'm in the UK, I broke my encoder a week ago and picked up a new Celestron motor & encoder from a dealer for £43 inc postage & 20% tax ($60) - came with wire connections and the mounting bracket as well

PS - If you are in the US, couldn't you just buy a new encoder from US Digital, I thought about it but paying delivery and import duty and tax it wasn't worth it for me

I stripped my old motor down so I can give you the shaft dimensions if you need them

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#18 rmollise

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Posted 07 February 2014 - 03:47 PM

That is the standard (not plus) HC.

#19 Mitch Hamilton

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Posted 07 February 2014 - 03:51 PM

I'm in Canada

#20 RTLR 12

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Posted 07 February 2014 - 04:03 PM

Mitch,

That is an earlier series 3.XX non programmable hand controller...

Stan

#21 Mitch Hamilton

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Posted 07 February 2014 - 04:19 PM

Update: The seller has indicated he has "also recently installed an optional polar alignment telescope, a new main computer, and a brand-new right ascension motor assembly."

This sounds like a REAL fixer upper, getting more and more concerned...

If he has already replaced those parts why wouldn't he just finish refurbing the rest and sell it for a higher price?

#22 RTLR 12

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Posted 07 February 2014 - 04:32 PM

This doesn't sound like something that I would want to get involved with. He has spent a lot of time and money on this mount and it still is not working and he wants to get rid of it. You also want a mount that has a programmable hand controller. I think I would pass if I were you.

Stan

#23 Mitch Hamilton

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Posted 07 February 2014 - 05:04 PM

Yea I was under the impression that he wasn't tech savvy to begin with but these repairs make me think he knows he is sitting on a lemon and he wants to move it.

#24 RTLR 12

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Posted 07 February 2014 - 05:19 PM

That is something that I might be interested in buying, but only for the parts. I have so many mounts and spare parts that it would be worth something to me, but for some one to buy it and try to make the mount work properly it would be a real gamble.

Stan

#25 rmollise

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Posted 07 February 2014 - 05:24 PM

How can you tell? Is it the Celestron symbol? Are we sure all the programmable ones had the newer symbol? Anyhow...gotta say good catch on your part. ;)






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