Has anyone converted a Celestron Advanced GT ? #celestron


Pedro Miguel Barbosa Moutinho Nunes dos Reis
 

Hi
I have a chance of buying a used Celestron Advanced GT. It has no hand controller and the motors seem to be stuck, as per the seller's description. I haven't seen the mount yet.
Has anyone converted one?
Can you share any experience?

Thanks.


Khalid Baheyeldin
 

The Celestron ASGT is just an EQ5 mount.

The EQ5 mount is the most converted mount in the OnStep community.

Go to the Showcase page on the Wiki, and you will find a lot of examples there.


Pedro Miguel Barbosa Moutinho Nunes dos Reis
 

On Wed, Mar 17, 2021 at 03:41 PM, Khalid Baheyeldin wrote:
Go to the Showcase page on the Wiki, and you will find a lot of examples there.

 

 
Great! Tks


 

I have.  Khalid posted my step by step guide in the Files section.  Mine is not yet in the showcase page as I have not fully tested the GoTo capability, but everything works mechanically and electrically.  Detailed pictures in the link below along with comments on the motor mounting.  It was very doable.

https://www.amazon.com/photos/groups/share/MKiqEsgjSTmnTB1lCBFypg.cBjWVvWfsy_EeC9fJxsx5h


Pedro Miguel Barbosa Moutinho Nunes dos Reis
 

On Wed, Mar 17, 2021 at 06:53 PM, Otto wrote:
I have.  Khalid posted my step by step guide in the Files section.  Mine is not yet in the showcase page as I have not fully tested the GoTo capability, but everything works mechanically and electrically.  Detailed pictures in the link below along with comments on the motor mounting.  It was very doable.
Top.
Yours was not a motorized one originally right?
Did you somehow enhance it? relube, etc? I guess I need to service mine on arrival, if you have any link please share.

Great job, very nice ideas on your conversion. 
Thanks for sharing


 

On Wed, Mar 17, 2021 at 03:25 PM, Pedro Miguel Barbosa Moutinho Nunes dos Reis wrote:

Top.
Yours was not a motorized one originally right?
Did you somehow enhance it? relube, etc? I guess I need to service mine on arrival, if you have any link please share.

Great job, very nice ideas on your conversion. 
Thanks for sharing
Mine was motorized.  I removed all of the motors and electronics and sold them.  I have not done the tuning/re-lubing.  It seems to move pretty smoothly.  That may be next if I find the imaging performance needs it.  Now, the Advanced GT I believe has the upgraded ball bearing design over the previous versions.


George Cushing
 

Based on kit sales I'd estimate 50-60 of OnStep conversions are EQ-5s. Here's my faithful ASGT test mule.

NEMA brackets.jpg


Pedro Miguel Barbosa Moutinho Nunes dos Reis
 

Is this mount good enough for imaging?
I've seen/read contradictory opinions on various forums.
Also, I believe there are different versions, etc..
Anyone using this for photography?


Pedro Miguel Barbosa Moutinho Nunes dos Reis
 

On Fri, Mar 19, 2021 at 02:11 PM, George Cushing wrote:
Based on kit sales I'd estimate 50-60 of OnStep conversions are EQ-5s. Here's my faithful ASGT test mule.
 
Have you serviced it? Do you know the specs for the bearings and washers?
Can't find that anywhere. 


George Cushing
 

Frankly I'm surprised with the quality of the imaging being done or EQ-5 types, particularly the old vixen SPs.

The ASCG-5 was the best edition of this mount sold. Unfortunately the the electronics were not as reliable as a commercial product should be. Motor control boards were particularly subject to failure. I have bought several DOA ASGTs for about $250 (retail was $800!). The tripods bring $125-150 and motors sell for $75. It took me three DOAs to get one worker. But they are selling in the $350-400 range working. So they are worth more for parts. I recent sold a head and a AL130 tripod for $175 and have sent a couple to eastern Europe.

Most of these are running OnStep. If Howard hadn't created OnStep they'd probably still be sitting in my basement.

I have never had a ASCG-5 that I thought needed more that adjustment of the worm gears. If you haven't worked on older CG-5s that you have had to malletize to get the RA axle to rotate or roast in the oven at 250°F for 30 minutes to get apart, you can't fully appreciate the difference in the ASCG-5. 


Pedro Miguel Barbosa Moutinho Nunes dos Reis
 

Well, just got the mount.
It seems usable enough. Tested the motors, they seem to work just fine. 
Now, anyone has an idea on how can I test the electronics without the HC and cables
I don't want to just go and buy those just to find out that the electronics on the mount are fried.. :)



Mark Christensen
 

I used a stock CG5-AST (with minor re-greasing and adjusting) for years with a 150mm f/5 Newt. Worked fine at 750mm focal length. Just be realistic with regard to the focal length you use.
For example, when I moved to a 150mm f/9 RC (1350mm focal length) I had to go to a CGEM. This is all pre-OnStep. But the basic mount is sound - realize that switch from the Celestron servo motor system to the Onstep stepper syste won't magically change the mechanical limitations of the mount.

So the basic mount is sound at moderate focal lengths. If you get greedy and try to use it at long focal lengths you are looking for trouble, not matter what motor and software control system you use.

Mark C.


Pedro Miguel Barbosa Moutinho Nunes dos Reis
 

On Tue, Mar 23, 2021 at 05:16 AM, Mark Christensen wrote:
I used a stock CG5-AST (with minor re-greasing and adjusting) for years with a 150mm f/5 Newt. Worked fine at 750mm focal length. Just be realistic with regard to the focal length you use.
For example, when I moved to a 150mm f/9 RC (1350mm focal length) I had to go to a CGEM. This is all pre-OnStep. But the basic mount is sound - realize that switch from the Celestron servo motor system to the Onstep stepper syste won't magically change the mechanical limitations of the mount.
Thanks for your input. That's about what I have right now, an SW 150 PD-S, 750mm focal length, f5.
I take that is your opinion that even the motors/etc are in good working order I will get better results converting it to Onstep?

Thanks
Pedro


George Cushing
 

You'll notice there are three RJ-11 ports on the mount. Left to right they are hand control, Dec drive and guider. Folks all too frequently put the Dec cable into the guider port, which is hot (12V). That kills the Dec encoder. You can't buy the encoder assembly as it's proprietary, you have to buy the whole motor assembly. The only work around is to source the transmitter/receiver chip from China and do a reflow repair. This was HP technology, but Broadcom owns and makes the chips now. To purchase them there are minimum purchase requirements that make it pretty expensive.

But it doesn't end there, as the current shorts through the encoder it kills the Dec µcontroller on the motor board. Used motor boards are scarce and trending toward $200. Figure $40-50 plus $15 postage for a used Plus hand control. The Dec cable is pretty straight forward cross over RJ-12 6P/6C and the hand control's cable is integrated with the unit. figure $10-15 for the cable. I can convert 3 GC-5s to OnStep with that kind of money.

I recently went through my junk astro PCBs and counted ten Nexstar motor control boards, just saying.


Pedro Miguel Barbosa Moutinho Nunes dos Reis
 

On Tue, Mar 23, 2021 at 12:47 PM, George Cushing wrote:
But it doesn't end there, as the current shorts through the encoder it kills the Dec µcontroller on the motor board. Used motor boards are scarce and trending toward $200. Figure $40-50 plus $15 postage for a used Plus hand control. The Dec cable is pretty straight forward cross over RJ-12 6P/6C and the hand control's cable is integrated with the unit. figure $10-15 for the cable. I can convert 3 GC-5s to OnStep with that kind of money.
I bought this thinking on convert it anyways....
But if all is ok I may be able to sell the parts to someone :).
I just found a fellow stargazer in our local community that has the same mount and will lend me the needed cables/HC to test this. Lets see how it goes.
Is there any change that I fried the HC on the tests??

Thanks


Pedro Miguel Barbosa Moutinho Nunes dos Reis
 

AFAIKS all is workin ok... now decisions, decisions, should I sell this and convert the mount or try to find a used HC? :) 


Pedro Miguel Barbosa Moutinho Nunes dos Reis
 

Making as alignment and slewing to Jupiter


Khalid Baheyeldin
 

Pedro,

If you have the skill and patience to convert the mount then go for OnStep. You will not regret it.

By skills, I mean that you can mount the motors (which is not a big challenge for EQ5 type mounts), run wires to a controller, do some soldering and so on ...
By patience, I mean you can look up stuff when you get stuck or confused, and have some perseverance.


Pedro Miguel Barbosa Moutinho Nunes dos Reis
 

On Tue, Mar 23, 2021 at 07:36 PM, Khalid Baheyeldin wrote:
If you have the skill and patience to convert the mount then go for OnStep. You will not regret it.
I'm already converting the EQ3 ;). It is a testbed for this one. I was told that the electronics were probably busted when I bought it. 
I'm hoping that this weekend I'll have it ready for the firsts tests. I'm still a bit confused about the protocols to use the kstars, stellarium, etc etc.. but I'll get there :)
Thanks!


George Cushing
 

No, as long as you stay away from the guide port.

You will most likely get an Error 16 or 17. HBX is not able to communicate with the drives.