Garmin GTX 327 Transponder - inoperative 3 digit

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RMarkSampson
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Garmin GTX 327 Transponder - inoperative 3 digit

Post by RMarkSampson »

This is likely the only good news story I have for 2020.

My transponder "3" digit started to get get harder and harder to activate a "3" when entering a squawk code - then that digit stopped working all together. ATC was tolerate for a few flights when I needed to request a different squawk code not containing a 3 digit. Calling my avionics shop - shipping the transponder off to Garmin was their only course of action. Price $600-$700 depending on if I wanted to wait for its return or go with a minimal downtime swap option. Turns out every part and service action for the transponder is pretty much a Garmin shop action but I decided to peek inside. I figured it would not be any more costly if I messed something up - but happily I was able to fix the problem with only a few hours of poking around.

I had some downtime as Tropical Storm Eta passed by Florida to remove the transponder from the plane for a few days. I had a copy of the transponder maintenance manual for the unit and it described the actions required to open it up. There is only about 6-8 screws to isolate the front panel with all the buttons from the rest of the unit. The display even detaches from the front panel with two screws and a electrical ribbon connector. I could feel that the 3 button felt and clicked like all the other buttons. It was not mechanically broken. So a put a few drops of LP1 around the button and let is soak in - and then used compressed air to remove any excess LP1. I then reassembled the unit. Installing the transponder back in the aircraft a few days later - there was first no difference for the first half-dozen click attempts, but then the 3 button came back. It now works every time you press it.

I'm knocking on wood as I type this - but for now, my transponder is fully capable and I no longer need to have long conversations with ATC about what squawk codes I can punch into my transponder. Many fixes cost $$s, but some avionics fixes can be simple and not drain the wallet.
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Derek
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Re: Garmin GTX 327 Transponder - inoperative 3 digit

Post by Derek »

Good to know, thanks! What is LP1?
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Steve
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Re: Garmin GTX 327 Transponder - inoperative 3 digit

Post by Steve »

LP1 is a thin lubricant and water displacer. I'm happy to hear that it worked for Mark. For cleaning electrical contacts I use Deoxit.

Steve
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