Garmin 750 with 650

[PiperW]

I have Garmins 500, 750, and 650, the 750 and 650 are cross filled.

Today I pulled the breaker on the GPS1 750 to proof the coms/nav would default to the 650.

It didn’t happen, which makes me think I have a issue with how my garmins are configured.

I plan to call Garmin tomorrow but thought maybe someone can save me a call.


Btw
Transponder, same story.

Thanks

 

[flyingcheesehead]

I have Garmins 500, 750, and 650, the 750 and 650 are cross filled.

Today I pulled the breaker on the GPS1 750 to proof the coms/nav would default to the 650.

It didn’t happen, which makes me think I have a issue with how my garmins are configured.

What do you mean by "the coms/nav would default to the 650"?

Do you have a remote audio panel controlled via the 750?

Transponder, same story.

Confused still. Remote transponder also controlled by the 750? What behavior were you trying to test there, that it would work and remain in the same mode with the same squawk? How were you testing it?

 

[PiperW]

Simply put, my audio panel is part of the Garmin 750.

The 750 and 650 each has (2) com freq's. I normally program the 750 coms for my air flight, and my 650 coms for ground (weather, tower, ground). Staying ahead of the plane.

while practicing different type failures:
I pulled the breakers (com1 and GPS1) on the 750 hoping the air coms I had entered would default to the Garmin 650. It didn't and I had no way to physically enter the numbers into the 650.

edit:
Coms problem first, then we can talk about the transponder after we are on the same page.

 

[Ryan Klems]

So you have a GMA 35/35c remote audio panel it sounds like. It's not part of the 750, but the 750 controls it. So you pulled the breakers for the GTN 750 and it did not fail over to the GTN 650 for com? (Nav isn't a part of that failsafe equation.) It does sound like the installer has it incorrectly wired/configured so that the failsafe is not functioning properly. This seems to be a fairly common error with the GMA 35 install.

 

[flyingcheesehead]

Simply put, my audio panel is part of the Garmin 750.

There is no audio panel that's part of the 750. There is the GMA 35/35c, that is the remote audio panel I was asking about. So, you have that, we're at least starting to be on the same page.

Same goes for the transponder - If you're controlling it on the GTN 750, it's a GTX 345R (remote) transponder. It's not part of the 750, but the 750 is where you interact with it.

The 750 and 650 each has (2) com freq's. I normally program the 750 coms for my air flight, and my 650 coms for ground (weather, tower, ground). Staying ahead of the plane.

Good technique, I do the same.

while practicing different type failures:
I pulled the breakers (com1 and GPS1) on the 750 hoping the air coms I had entered would default to the Garmin 650. It didn't and I had no way to physically enter the numbers into the 650.

The frequencies you entered on the 750 won't automagically be tuned on the 650. The frequencies you already had on the 650 can be changed on the 650, though.

I think @Ryan Klems is right, that the install manual wasn't completely followed in your case, and that the 750 is connected as Com1. Do you have a separate breaker for the audio panel?

 

[PiperW]

You guys are spot on.

My 750 is connected to the Com1.

I do not have a separate breaker for the audio panel.

When I pull the CB for com 1, I lose communication in my 750 but I still can toggle (the GMA 35?) to com2. My transponder squawk is still working in the 750 and 650.

When I pull the CB GPS1, the 750 goes blank (dead) and I lose transponder and communications in the 650.

The Garmin tech at my home field is currently scheduling me in to resolve. He also thinks it is a wiring issue.

 

[Ryan Klems]

I definitely believe that the audio panel behavior is wrong, and due to the miswiring and misconfiguration of the GMA35, however the transponder behavior I believe is expected. What transponder do you have? A GTX345R? In a dual GTN + GTX345R install, the GTX is wired in over HSDB & RS232 to the GTN #1 and then GTN #2 is connected via HSDB to GTN #1. GTN #2 communicates with the transponder via the GTN #1, so if GTN #1 is lost, then there is no way for the GTN #2 to talk to the transponder. The GTX would continue to transmit, but you lose ability to control it as well as would lose traffic input to the GTN #2 (you would still get traffic callouts via the GTX, but no displayed traffic)

edit: Additionally, I'm a bit surprised you don't have a separate breaker for the audio panel, it's required per the install manual (since this isn't an STC install, I understand it's not the "law", but still...). I wonder what it's wired to.

 

[PiperW]

I have a Garmin tech looking at my stack next week. I plan to show him your comments in hopes to answer your questions.

Thanks again!

 

[Ravioli]

I also think you need to read up some on what "Cross Filling" actually means.
Your route information should cross fill, but the nav and com freqs should not.
"Cross fill" is not equal to "Fail over"

 

[PiperW]

I also think you need to read up some on what "Cross Filling" actually means.
Your route information should cross fill, but the nav and com freqs should not.
"Cross fill" is not equal to "Fail over"

Yes, I understand that. Should have been more clear on the cross filling comment.

I will report back with the solution from the Garmin tech.