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Garmin GTX327

Capt

Well Known Member
Quick Q for those operating the above TX.

My fairly new TX I can’t turn off at the panel face, any ideas guys?

Cheers.
 
For those of us in the US where ‘transponder set to ‘ALT’ any time you’re operating’ is now the rule, there’s a setup menu item to do that. Or, turn it off, if you don’t want that.
 
I was asking how to turn the unit off, not turn off ALT, I can’t shut the whole unit down!
 
Are you pressing the "OFF" button in the 4 o'clock position next to the ALT button? You didn't specify. Try holding it for 2 seconds to see if that works. If not, then your buttons might be dirty. Do the balance of the buttons work?
 

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If you want to check out your unit configuration you can go to the Garmin GTX 327 installation manual page 34 (manual page 5-4) and check and see if there is some sort of key lock or always on selection:

https://static.garmin.com/pumac/GTX327Transponder_InstallationManual.pdf

If no configuration option then you could try to clean the contacts in the keypad if you feel adventurous. That will entail opening up the unit and removing the faceplate being careful with the interconnect ribbon cable. And then use a spray can of contact cleaner safe for plastic. Or whatever else might make sense.

In the interim there is always the breaker or fuse if you want the unit off during flight.
 
If it's wired to turn on with the avionics switch, but there is no avionics switch, then you can't turn it off unless you revise the wiring.
Avionics master in is Pin 1, remove that wire to regain control.
 
I have the manual, I’ve read the manual, there’s no avionics switch, just 1x radio & the 327, each turn on separately. The unit is near new, all other buttons perform as intended, I just can’t turn it off at the unit itself. The manual states do not turn off master with the unit still powered up.
I no longer turn it on for fear of damaging it, it’s a paperweight now🙁 I’m not a Garmin fan but it came with the plane.
 
I have the manual, I’ve read the manual, there’s no avionics switch, just 1x radio & the 327, each turn on separately. The unit is near new, all other buttons perform as intended, I just can’t turn it off at the unit itself. The manual states do not turn off master with the unit still powered up.
I no longer turn it on for fear of damaging it, it’s a paperweight now�� I’m not a Garmin fan but it came with the plane.
I thought you said you couldn't turn it off???

I repeat: remove/cut the wire going to pin 1 to regain front panel on/off control.

PS: you won't damage it the way it is, just not the recommended procedure.
 
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Avionics Master On

I have the manual, I’ve read the manual, there’s no avionics switch, just 1x radio & the 327, each turn on separately. The unit is near new, all other buttons perform as intended, I just can’t turn it off at the unit itself. The manual states do not turn off master with the unit still powered up.
I no longer turn it on for fear of damaging it, it’s a paperweight now�� I’m not a Garmin fan but it came with the plane.

Hello Capt!

Walt is correct. For reference, I am looking at the GTX 327 Installation Manual, Revision S, page C-1. If you are do not have this specific revision of the manual, I highly recommend emailing us at [email protected] to grab a copy.

"Avionics Master On (P3271-1). When tied to 11-33 VDC input (P3271-15) provides automatic unit power up. When power is applied the unit will power up in the last mode selected"

In other words, with that pin tied to the power input, anytime the power bus connected to the unit is energized, your transponder will power on. Remove pin 1 from the specified connector and all will be well.

Let us know how else we can help!

Thanks,

Justin
 
Thanks for the replies guys, when next I remove the fwd fuse hatch (a million screws!)to access the radios I’ll remove pin No 1 although the A/C has no avionics master.
 
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Update if anyones interested. The TX has no pin 1 wire, it just gets turned on via the faceplate when the ship has power. I sprayed contact cleaner into the removed faceplate and worked the buttons many times, left it in the sun to thoroughly dry out. Reassembled all worked fine……but yes there’s always a but! After a couple of uses, say 6 it’s failed completely now, can’t turn it on!
Power is going to the plug as the back of the rack, I think I’ve got a lemon, but it is a Garmin I guess! -(
 
It might be worthwhile taking into a shop and getting them to have a look at the buttons... or if you're confident enough, have a look yourself. If its an older unit you don't have to worry about losing your warranty... so nothing ventured, nothing gained.

Worth a shot.
 
It might be worthwhile taking into a shop and getting them to have a look at the buttons... or if you're confident enough, have a look yourself. If its an older unit you don't have to worry about losing your warranty... so nothing ventured, nothing gained.

Worth a shot.

I’ve already had the whole unit in pieces including the faceplate/button assembly, nothing obvious. Radio shop wants the Earth just to open it up! I might have to bite the bullet and buy a proper non Garmin TX, never did like Garmin stuff🙁
Anyway m done with it, paperweight at best!
 
I’ve already had the whole unit in pieces including the faceplate/button assembly, nothing obvious. Radio shop wants the Earth just to open it up! I might have to bite the bullet and buy a proper non Garmin TX, never did like Garmin stuff🙁
Anyway m done with it, paperweight at best!

Pretty hard to spend repair money on these when the used market has working ones for $400. But if you want to go new (plus I see this post is in the ADSB section) a new Trig mode S-ES can be had for $2K (US); I’m happy with mine, no issues.
 
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