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Old Nexstar GPS with new hand control - how to make it work?

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#1 perryboat

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Posted 19 July 2019 - 12:34 AM

I have an old GPS 11. I bought it used about 8 years ago. I don’t know the versions, but it had the GPS alignment. I loved it. Then the hand control broke. Blank LCD. I tried to fix it, but probably just made it worse. So I bought a new hand control. It won’t talk to the scope. I ran Celestron Firmware Manager through the hand control RS 232 port, it worked for the hand control but doesn’t see the scope.

When I check the version though the hand control utility menu, it gives “?.?? ?.??” For the motor control.

How do I get my scope back???

Thanks.

Edited by perryboat, 19 July 2019 - 12:36 AM.


#2 Michael_Swanson

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Posted 19 July 2019 - 01:19 AM

Hi Perry,

 

The newer hand controls (the "version 4 HC" and the "NexStar+ HC") will only recognize the mount if the motor control (MC) is running firmware version 4.06.  Try the connection through the HC using these instructions from my website to update your MC to version 4.06:

https://www.nexstars...pgradeHowTo.htm

Sometimes though, the MCupdate program is unable to connect to the MC board via that connection.  First just be sure MCupdate is using the correct comm port (it is okay to try every comm port MCupdate lists) but if it cannot see the MC board, you will need to get a PC Port cable (previously known as the "programming" cable) as described in connection method 3 on that page I linked to.

 

That should get things running but there is a caveat.  The current NexStar+ HC (which you have) when loaded up with the latest firmware doesn't work well with the oldest NexStar 8/9.25/11 GPS mounts.  On affected mounts, there are communication issues that result in "no response" errors and sluggish arrow button response.  If that is the case on your mount, you have two options. 

 

The first is to roll back to older firmware on the NexStar+ HC using the instructions I posted here:

https://www.nexstars...xStarGPSFix.htm

The caveat though is if your scope is displaying an incorrect DATE after the GPS links, you will lose the use of your GPS and will need to manually enter at least the date.  If that is the case on your mount, you turn GPS on and off in the Utilities menu.  (you can turn it on, get a link for the location and time, then turn it off and manually fix the date as you start the alignment routine)  Hopefully Celestron will one date fix the NexStar GPS comms issue as their latest NexStar+ firmware fixes the GPS date issue.

 

Your second option is to return the NexStar+ HC (or keep it for future use) and get a version 4 HC.  The latest firmware on that HC (NXS 4.22) works fine with the NexStar GPS mount and it also addresses the GPS date issue.  The version 4 HC is no longer in production but a reliable source for them has been "wing_and_sons" on Ebay.

 

Best regards,
Mike Swanson
Author of "The NexStar Users Guide II"
Author of "The NexStar Users Guide"
Author of "NexStar Observer List"
https://www.nexstarsite.com


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#3 perryboat

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Posted 19 July 2019 - 01:25 AM

Thank you! I tried the MC Update through the hand control, and it wouldn’t work on any .com port. I’ll work through the rest of the options. I really appreciate the assistance!

#4 Geo.

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Posted 25 July 2019 - 06:19 PM

Funny thing I noticed while poking around in this 8i. 

 

P1016474.JPG



#5 mclewis1

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Posted 25 July 2019 - 09:13 PM

It kind of makes sense that there was common firmware ... C sure didn't want to do a lot of variations. Is there an open header on the 8i's MC board for a GPS connection?



#6 Michael_Swanson

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Posted 26 July 2019 - 12:28 AM

The hardware might have been the same (I'm checking with one of the circa 2000 engineers) but the firmware was definitely different between the NexStar GPS and 5i/8i mounts.  Seems likely Celestron repaired this particular 8i using a GPS MC board after loading the i series MC firmware.  They just forgot to peel off the "4.05" label.

 

If the hardware is the same, at a minimum we should be able to use the boards interchangeably though it may require a PIC programmer to load the correct firmware.

 

Best regards,
Mike Swanson
Author of "The NexStar Users Guide II"
Author of "The NexStar Users Guide"
Author of "NexStar Observer List"
https://www.nexstarsite.com



#7 Michael_Swanson

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Posted 26 July 2019 - 07:10 PM

Confirmed - the 5i/8i MC board is hardware compatible with the NexStar 8/9.25/11 GPS MC board. Depending upon the actual version, the bootloader of a 5i/8i board may or may not be compatible with loading the GPS firmware via MCupdate. If not, it would need to be loaded with a PIC programmer as 12bass has described in this post
https://www.cloudyni...re-update-info/

So, this opens up a whole new source of parts to repair the more expensive NexStar GPS line.

Best regards,
Mike Swanson
Author of "The NexStar User's Guide II"
Author of "The NexStar User's Guide"
https://www.NexStarSite.com

Edited by Michael_Swanson, 26 July 2019 - 07:12 PM.


#8 Geo.

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Posted 01 August 2019 - 07:23 PM

It kind of makes sense that there was common firmware ... C sure didn't want to do a lot of variations. Is there an open header on the 8i's MC board for a GPS connection?

No, the CN-16 GPS uses the Aux port on the NS-8i. Then the GPS is a client of the HBX. On the NS-GPS the the GPS receiver signal is routed to J10 on the main board and then on to the HBX. Motor control is never never directly concerned with GPS output. Same for the compass and Aux 2 and 3. These signals are run through a logical buffer (74HC125) for multiplexing. 



#9 mclewis1

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Posted 02 August 2019 - 09:24 AM

George,

 

I was thinking of the potential for the board being used in either scope (with different firmware) ... if there was an open header for the internal GPS connection. Nothing to do with the external AUX connected devices.

 

I think I'll start a new thread to discuss the "genealogy" of some of the NexStar architecture. I have some questions about common boards vs. common firmware in some of the scope families.



#10 perryboat

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Posted 06 August 2019 - 04:19 PM

Update to my original post. After purchasing a Version 4 hand control and building a PC programming cable and updating the motor control firmware, I have my telescope back! Thanks for the help. Mike, you are an incredible resource!

#11 Michael_Swanson

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Posted 06 August 2019 - 06:46 PM

You're quite welcome.

 

Best regards,

Mike




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