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Nexstar 8 GPS Error 16/17

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#1 AdamColliss

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Posted 08 April 2013 - 02:38 AM

Hi

I've been getting the dreaded Error 16/17 errors intermittently on my Nexstar 8 for the last couple of years, but recently they have got far more common and at present it seems the scope seems to do it every time. I've tried spreading the centre of the power connector, updating the firmware and also tried a couple of different power adapters, also powering it directly off a motorcycle battery and with a 12v car adapter, all with no success. I've reseated all the connectors I can find, also made no difference.
Has anyone got any other ideas I could try? I can't find anywhere that sells the motor control boards to the UK, so I'm a bit stuck. Is it worth removing the OTA and getting a new mount or do you think it would be more cost-effective to sell it as spares/not working on ebay and get a new scope?
Any help/advice greatly appreciated.

Thanks
Adam

#2 mclewis1

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Posted 08 April 2013 - 10:09 AM

Adam,

Since you've done the MC firmware upgrade I'll assume that you've got a PC port cable (not the one that plugs into the base of the hand controller)? If so I would download a copy of NexRemote (it's free), un plug the hand controller and run the mount from a PC using NexRemote to see if the hand controller is causing your problem. What version of hand controller (HC) firmware are you running?

If the HC is causing the problem then before replacing it you can try a couple of things. Put the hand controller on one of the AUX ports to see if the HC port itself is a problem. If that doesn't change anything cut the end off of the hand controller cable and replace/recrimp on a new RJ11/12 connector. Make sure you note the pin/wire orientation of the existing cable before you cut it off.

If it is the hand controller itself then you can get another one quite easily. You can use any v4.xx hand controller from any Celestron scope/mount. It probably won't work right off but all you'll need to do is re flash it with any of the NXS4.xx firmware and you'll be fine. If you are currently using v2 firmware you'll loose the north and level auto alignment but you'll gain a number of other benefits.

If it's not the hand controller and you've got good power, good external connections, and checked all the internal connections you may indeed have a bad MC board.

#3 redfox

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Posted 08 April 2013 - 06:16 PM

Try company called firstlight optics of Exeter they helped me out with a alt motor for my cpc800 no other company wanted to no as celestron don't look after their uk customers. Firstlight optics sponcer a astronomy site aswell called stargazers lounge have a look.

#4 gastargazer01

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Posted 08 April 2013 - 08:43 PM

I have had the same problem with my CG-5 mount and I also saw that encoder may have cause problems as well. I did upgrade my mount and have not had a chance to swap HC and cables etc to test. Mine started when I enabled the GPS and thought it was that so sent the GPS back and got a replacement and still had the issue only when the GPS was enabled. I am going to follow to see what you find out and if I get a chance to test my mount I will let you know what I find. I suspect a MC board :(
I think I have tried everything on Marks list but I am going to retest with his suggestions.

#5 AdamColliss

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Posted 09 April 2013 - 05:43 AM

Thanks for the replies - I've been quoted £235(!) for a new motor board so I will take the scope apart and try re-seating the connectors and then re-flash the board and HC again. I'll update when I've done this.

#6 rmollise

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Posted 09 April 2013 - 07:49 AM

It's unlikely to be a motor problem since both motors are affected (16 and 17). Carefully check (with a multimeter) all cables and connections and use denatured alcohol or zero residue (electronic) cleaner on the receptacles.

#7 AdamColliss

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Posted 12 April 2013 - 12:17 AM

Hi
Quick update, I found a 3.2A/12V PSU from an old laptop and using that I managed to flash the Hand Controller up to 4.17, but then had problems seeing the Motor Control boards to flash them. Eventually I managed to flash the first board, but lost contact while doing the second one. I powered off and powered back on then amazingly managed to get the second one done. Powered off, powered on - sure enough error 16 and 17 again. One last try - powered off, powered on - all working! I've since powered the scope off multiple times and powered it on and all is good. No idea how long it will be stable or if the issue is finally fixed, but glad it's working at the moment anyway!
Thanks for all the advice!

#8 gastargazer01

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Posted 16 April 2013 - 11:42 PM

Well I have been able to do some testing because my CGEM mount arrived a few weeks ago and it is looking like the CG-5 HC has a problem because when I use the CGEM HC on the CG-5 it works fine. I went ahead and reflashed the MC firmware with the new HC and it did not fix my problem. When I run CFM it does not see the CG-5 HC but does see and works fine with the CGEM HC. I removed the back of the CG-5 HC and checked the internal connections and that the RJ contact wires lined up.
This HC has worked intermittently with the data cable and now not at all, but the HC works fine by itself.
I am going to call Celestron and see about a replacement because it should still be under warranty.






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