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GNS480 issues


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Hi All,

Ever since I had my GTX345 installed, I've been having issues with our 480. I don't think it's seated properly and we keep getting a "Altitude encoder communications failure" message. Anyone know of a shop in southern California that has experience troubleshooting connection issues in 480's?

 

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It's not possible for one function to stop working due to improper seating, since all the pins are at the same height. Nothing at all would work. However, It is possible for one pin to be unlocked in its connector, and then push back when the radio is inserted.That's the most common problem and easy to see. With the radio out, you can push on each pin individually to be certain it is locked. You have to be careful not to bend them, and you need an eight inch long 3/16" diameter plastic tool, with a flat end, such as an artist brush. If you find an unlocked pin, the affected connector has to be removed from the backplate, or the backplate from the rack, for access to push the pin all the way in to lock it. 

The altitude encoder connects to the 480 on plug P5 pins 30 and 44. This is the 480's RS232 Channel 8. If you put the 480 into Ground Maintenance Mode, there is a page to see the data stream coming from the encoder. The transponder is wired to P5 pins 2,42,22, which is the 480's RS232 Channel 6.

These connections are made with very small, high density pins, and 20 to 26 gauge wire, and they are easily damaged during other work. It's also possible that one of the affected pins has a wire that is partly broken. Or the baud rate is incorrect for the RS232 data stream.

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On 10/26/2019 at 10:11 AM, philiplane said:

It's not possible for one function to stop working due to improper seating, since all the pins are at the same height. Nothing at all would work. However, It is possible for one pin to be unlocked in its connector, and then push back when the radio is inserted.That's the most common problem and easy to see. With the radio out, you can push on each pin individually to be certain it is locked. You have to be careful not to bend them, and you need an eight inch long 3/16" diameter plastic tool, with a flat end, such as an artist brush. If you find an unlocked pin, the affected connector has to be removed from the backplate, or the backplate from the rack, for access to push the pin all the way in to lock it. 

The altitude encoder connects to the 480 on plug P5 pins 30 and 44. This is the 480's RS232 Channel 8. If you put the 480 into Ground Maintenance Mode, there is a page to see the data stream coming from the encoder. The transponder is wired to P5 pins 2,42,22, which is the 480's RS232 Channel 6.

These connections are made with very small, high density pins, and 20 to 26 gauge wire, and they are easily damaged during other work. It's also possible that one of the affected pins has a wire that is partly broken. Or the baud rate is incorrect for the RS232 data stream.

Thanks for the information. I will check it out. Given that Garmin is no longer supporting the 480, will I be up a creak without a paddle if it turns out that one of the pins is damaged or should a shop be able to repair the connector?

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On 10/26/2019 at 10:11 AM, philiplane said:

It's not possible for one function to stop working due to improper seating, since all the pins are at the same height. Nothing at all would work. However, It is possible for one pin to be unlocked in its connector, and then push back when the radio is inserted.That's the most common problem and easy to see. With the radio out, you can push on each pin individually to be certain it is locked. You have to be careful not to bend them, and you need an eight inch long 3/16" diameter plastic tool, with a flat end, such as an artist brush. If you find an unlocked pin, the affected connector has to be removed from the backplate, or the backplate from the rack, for access to push the pin all the way in to lock it. 

The altitude encoder connects to the 480 on plug P5 pins 30 and 44. This is the 480's RS232 Channel 8. If you put the 480 into Ground Maintenance Mode, there is a page to see the data stream coming from the encoder. The transponder is wired to P5 pins 2,42,22, which is the 480's RS232 Channel 6.

These connections are made with very small, high density pins, and 20 to 26 gauge wire, and they are easily damaged during other work. It's also possible that one of the affected pins has a wire that is partly broken. Or the baud rate is incorrect for the RS232 data stream.

Actually, sorry, I disagree.  I have found my guys have put connectors back into the backplate and not tightened the screws all the way either on the connector as it attaches to the backplate or on the backplate attachment to the rack and it does cause intermittent/hard failures.  Now, I also totally agree with you and check the connections.  The encoders have also been know to go south and did the GTX345 get installed with the GAE12 or tapped into the existing encoder?  

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7 hours ago, carusoam said:

Excellent input Greg...

We learn so much from the various experts in different fields...

Thanks for sharing the details...

Best regards,

-a-

Wait a minute!!!!!!!  Was that a compliment?  I don't deserve that!!!!  LOL, we are all in this together and we need to bring back that community feel to OUR industry.

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Was the old transponder a GTX327 or GTX330?

What is your encoding source?

I would suspect they had an icarus alt from the GTX feeding the GNS480. More than likely when they did the GTX345 upgrade, that was not kept or reconfigured.  A lot of shops used GTX transponders to convert grey code to serial, or just to rebroadcast it instead of splicing.

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