G3X, GDU 37x to GTR200

I'm configuring a two-screen G3X with a GTR 200, using the built-in intercom.

Does it matter which GDU provides the aux (warning) audio inputs? Currently I have the audio wired from the MFD (GDU375) but I'm not hearing any audio warnings/alerts. Everything else seems to be working nominally...

flyeyes said:

I'm configuring a two-screen G3X with a GTR 200, using the built-in intercom.

Does it matter which GDU provides the aux (warning) audio inputs? Currently I have the audio wired from the MFD (GDU375) but I'm not hearing any audio warnings/alerts. Everything else seems to be working nominally...

Click to expand...

Hello James,

Please start by visiting the SOUND page in config mode. There are multiple parameters there that are important in determining the source of audio alerts, the volume, and over which wires the alert messages/tones are played.

ALERT OUTPUT
This parameter lets you specify whether the alert audio is played over the MONO output or on both the MONO and STEREO outputs.

The ideal way to do this when you are using a GTR 200 is to wire the mono output from pins 1,18 on the GDU 37X to one of the two aux audio inputs on the GTR 200.

If you use the mono alert audio output in this manner, you should set the ALERT OUTPUT field to MONO.

ALERT SOURCE
This parameter lets you specify which display provides the alert audio output signal to the GTR 200. Since you have the GTR 200 connected to your MFD, this field should be set to MFD.

If you have this selection set to AUTO, the alert source prioritization is PFD1, MFD1, PFD2, so the MFD doesn't provide the alert audio unless PFD1 is not available.

One point to consider. Many of us wire the mono alert audio from the PFD instead of the MFD. In the unlikely event of a PFD failure, we might move the MFD display to the PFD1 position at the first opportunity, and we would get our alert audio back by doing this.

ALERT VOLUME and MESSAGE VOLUME
These parameters determine the audio signal level at the alert audio output on the display. You might start by setting these to 9 or 10 just to make sure there is enough signal to break the squelch on the AUX inputs to the GTR200.

You will also notice that there are AUX1/AUX2 input squelch settings on the GTR 200 that you can also adjust if the alert audio is not breaking squelch.

Finally, notice that at the bottom of the SOUND page on the PFD, there are soft keys that you can press to test the Alert and AOA audio which should make it very easy to troubleshoot your audio installation.

Let us know if you have additional questions.

Thanks,
Steve

Thanks, Steve.

That's exactly the guidance I was looking for. Most of those things I had already done, but not the complete list. It'll be a couple of days before I get to the hangar.

Is there a test for the music feature? Currently I have the airplane stacked in the back of the hangar, and the XM antenna isn't hooked up (waiting on a 90 degree TNC connector). I have the music wired from the MFD to a small 3PDT switch so I can switch music sources between the G3X and a 3.5mm phone jack. The aux jack works great in the hangar with my iPhone.

Also, I have the G3x connected to the GTR200 with the CAN bus, no serial. I'm planning to add a GNS400W. Can I connect RS232 out from the GNS to push frequencies to the GTR200?

flyeyes said:

Thanks, Steve.

That's exactly the guidance I was looking for. Most of those things I had already done, but not the complete list. It'll be a couple of days before I get to the hangar.

Is there a test for the music feature? Currently I have the airplane stacked in the back of the hangar, and the XM antenna isn't hooked up (waiting on a 90 degree TNC connector). I have the music wired from the MFD to a small 3PDT switch so I can switch music sources between the G3X and a 3.5mm phone jack. The aux jack works great in the hangar with my iPhone.

Also, I have the G3x connected to the GTR200 with the CAN bus, no serial. I'm planning to add a GNS400W. Can I connect RS232 out from the GNS to push frequencies to the GTR200?

Click to expand...

Hello James,

You are very welcome.

Once you get the XM antenna connected and the plane outside the hangar where it will pick up a signal, you can listen to the XM preview audio broadcast, even without a subscription, to test the stereo output from your GDU 375.

The GPS 400W doesn't know how to push frequencies to a GTR 200, but the capability to tune the GTR 200 from your G3X displays is so good that we doubt you will care.

Thanks,
Steve

g3xpert said:

but the capability to tune the GTR 200 from your G3X displays is so good that we doubt you will care.

Thanks,
Steve

Click to expand...

I gotta agree, I absolutely love the push button tuning feature on the GTR200

g3xpert said:

If you have this selection set to AUTO, the alert source prioritization is PFD1, MFD1, PFD2, so the MFD doesn't provide the alert audio unless PFD1 is not available.

Steve

Click to expand...

Correct me if I'm missing something but this means you would have to have audio wired from the PFD & MFD & PFD2 for the AUTO function to serve a purpose?

Thanks for the help, everything working nominally now.

Never could get the mono audio to work from the MFD, although the alerts and music work fine through the stereo output.

I gave up and pulled the wires out of the MFD, pulled new wires from the PFD to the GTR200 and all is well.

A couple of notes that may help the next person:

If you set the squelch to "0" on the aux audio on on the GTR200, and have it set to mute music, and it still doesn't work, All you will hear is silence, including the music input which you thought was working. D'Oh!

Running the stereo output from the MFD with XM to a small 3PDT toggle (MPJA currently has some subminiature switches which are suitable and really cheap) located with a 3.5mm stereo input jack works really well as a "music source select." I put mine in the right gear tower near a 12v jack for the iPhone.

Walt said:

Correct me if I'm missing something but this means you would have to have audio wired from the PFD & MFD & PFD2 for the AUTO function to serve a purpose?

Click to expand...

Hello Walt,

Well, you probably wouldn't wire all three.

The GTR 200 has AUX1 and AUX2 alert audio inputs, so you could wire the mono alert out from PFD1 to AUX1 and the mono alert out from the MFD to AUX2.

With this setup, and AUTO source selection, in the unlikely event that PFD1 became unavailable in flight, MFD would automatically go into reversion to perform the PFD1 function, and the aural alerts would be provided to AUX2 on the GTR 200.

While this is a feature of the system, we always recommend that you just wire mono alert audio from the PFD1 to AUX1 on the GTR 200 and keep it simple. It is quick and easy to move the MFD to the PFD1 position to regain alert audio should you ever have a need to do that.

Thanks,
Steve