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CNX80/GNS480 trouble

skywagon8a

MEMBER
SE Mass MA6
I have a CNX80/GNS480 in the 185 linked to a MX-20 display. The CNX80 screen suddenly went intermittent, now nothing. The back lighting on the buttons has done the same. The button back lights seem to be on two separate circuits as those on the right column seem to be separate from the rest. The radio is working as the map on the MX-20 is indicating correctly and I can hear the radio talking, just can't see the numbers on the screen. It also seems to do it's self testing correctly as the appropriate indications appear on the HSI.

I took it to a fairly new large radio shop in PLY where they didn't even want to look at it. Said that they would send it to Garmin. Seems to me that they are only interested in doing expensive installs. I suspect that there aren't any experienced avionics technicians working there. There were a lot of young faces.

This is the manual: https://www.manualslib.com/manual/846491/Garmin-Gns-480.html?page=1 The display is supposed to have a life in the 20,000 hour range. Since the switch back lights are also acting up I'm suspecting an internal connection of some sort. I can not find any reference in the manual for the troubles.

There is another shop further away that used to have some good old timers, if they are not retired.

Any ideas welcome. Does this really have to go back to Garmin or should a "real" avionics guy be able to solve the issue.
 
Most everything that Garmin makes (made) is shipped back to them for repairs. Very few functions are allowed at the dealer level.

Web
 
There is a 480 yahoo user group with numerous expert posters. I vaguely recall reading there is a third party fix for your issue which avoids the costly $1,000 plus fee Garmin charges. However, not sure when the last time your unit was updated, but now would be a good time for garmin to do that if you opt to send it in and drop a grand anyway. Good luck.

https://groups.yahoo.com/neo/groups/gns480-users/info
 
Well my old timer looked at it and couldn't get power to a certain section so couldn't fix it. Sent it to Garmin in Oregon and received it back three weeks later with a new circuit board for $1100 flat rate plus shipping.
 
Sky that is an installation manual you posted earlier. You would need a maintenance manual to even begin troubleshooting. I bought a KX155 to install in my plane for the exact reason that it has discreet components and the schematic "looks" like a radio ought to look. Unfortunately I had to spend $300 for a used "maintenance manual. It's about 3" thick but it's all there for an "old" radio guy to follow.
You are correct that there are not many real component level radiomen left. The ADSB thing has caused me to purchase a GTX335 and install it but I would not even consider opening the case.
 
This E-mail just came. Looks like I just got in under the wire.

GNS 480 (CNX 80) End of Service Life

SEPTEMBER 20, 2017
PRODUCTS AFFECTED:
Garmin GNS 480 (CNX 80) units are affected.
ISSUE:
The GNS 480 (CNX 80) is rapidly approaching end of service life. Due to limited parts availability, beginning January 1, 2018 repairs will be offered on a limited basis. Parts will only be allocated for repairs that affect airworthiness (no cosmetic repairs).
1754A
 
I forgot I started this thread 3 years ago.
This new thread is related: https://www.supercub.org/forum/showthread.php?58423-Testing-Com-Antennas

The CNX-80 had been operating properly when it was called back to Garmin for a software update making it conform to the newer GNS-480. This was in March 2009. It worked fine until the trouble which prompted this thread in 2017. It was sent back to the factory in Oregon (formerly II Morrow Apollo, now Garmin) for the flat rate repair. My past experiences with operating II Morrow's equipment had given me a bad taste for their products. However when the time came to upgrade to GPS, they were the only company to offer large screen (MX-20) and a WAAS GPS receiver. The CNX-80 had been receiving glowing reports by "experts" so I reluctantly went this route, The Garmin GNS-430 was not WAAS at the time. In retrospect, I should have skipped the WAAS and gone with the GNS-430. Unfortunately my initial reluctance of the II Morrow family has proven to be true. Their expensive flat rate repair lasted only three years and less than 50 hours. I don't fly much anymore.

To close this thread the CNX-80 was traded last week for a later GNS-480. Keeping my fingers crossed. Upgrading to a newer better system is not in the cards. The cost can not be justified by me.
 
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