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G3X GDU37X upgrade to GDU47X. Need to know.

pecanflyboy

Well Known Member
G3X, GDU370, GDU375, GTN650xi, with a GSU73. Upgrading to two GDU470 portrait displays. Things to know:

1. If you are going to use an Apple iPad to send flight plans from Garmin Pilot to a GTN, you must change the green configuration module in the PFD1 connector to a black configuration module. Must purchase separately.

2. There is no interconnect diagram to wire Connext when using the GSU73. Use the GAD29 Connext to any open RS232.
Referencing Rev AP of the G3X installation manual, and Rev 5 of the GTN650xi manual, the GSU73/GTN interconnect is on page 28-11. However, Garmin has directed me to the GAD29/GTN interconnect on page 27-40. This shows and RS232 connection between the GTN and the GDU4X0 using the GAD29 (3 wires). Garmin has confirmed that I can use this interconnect and associated Configuration Guidance for the GAD29 with the GSU73.

2.1 The interconnect diagram for the GSU73 between the GTN and the GDU37X for the MAPMX data only shows an RS232 "out" from the GTN to the GDU37X. You will get red "X's" in the NAV1 tuning on the GTN470 in this configuration. The fix is to add a RS232 "in" to the GTN from the GDU470 on the same channel. The GDU470 adds the function of tuning GTN frequencies remotely. For this to work, the GTN needs to receive data from the GDU (this was not a function of the GDU37X). Basically, the MAPMX needs data flow to and from to function properly.

3. For some reason Garmin made the mounting hole dimensions for the GDU470 just slightly wider than the GDU37X. So, you have to alter the panel and use a new mounting plate which must be purchased separately in an installation package. The holes are only a half a diameter apart (I suspect the engineers used the hole outer dimension of the GDU37X as the center dimension of the GDU470). If moving nutplates, you will not have edge distance unless you rotate the nutplate which is hard to do with the limited space. The installation kit nutplate is 1/4" wide and will work if you have the space. I had a supporting angle between the GDU's and was unable to use individual nutplates. So, I rebuilt the panel and powder coated. See pics

https://drive.google.com/drive/folders/1SUvk8HOEVLJBjHkp10NvQqzYyJfhXkkv?usp=sharing

4. The GDU470 is 1.5" + deeper than the GDU37X and the plugs are in a different position. If other components are closely mounted behind the GDU37X, you will have to move them and take into account that the plugs are more centered on the GDU470 and the installation is deeper.

5. If you are IFR, you will need to get another IFR pitot-static check to be in compliance since this is a new altimeter and/or you may have disconnected the pitot-static lines during installation.

6. You must re-configure ALL settings on the GDU470 after you erase or replace the configuration module. NOTHING transfers. This means you need to take pictures of all your configuration settings and menu settings before. Also, you will need to copy and save the fuel level calibration to the SD card as you will use this file to transfer these settings to the GDU470.

I'll update as I get information from Garmin, and lessons I learn during the installation.

$$
 
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There is no interconnect diagram to wire Connext when using the GSU73. Referencing Rev AP of the G3X installation manual, and Rev 5 of the GTN650xi manual, the GSU73/GTN interconnect is on page 28-11. However, Garmin has directed me to the GAD29/GTN interconnect on page 27-40. This shows and RS232 connection between the GTN and the GDU4X0 using the GAD29 (3 wires). Garmin has yet to confirm that I can use this interconnect and associated Configuration Guidance for the GAD29 with the GSU73. The G3X installation manual states: "The Connext interface and Bluetooth are not supported by the legacy G3X system and GDU 37X display." Hopefully, that means just the displays and not the GSU73.

Jimmy,

Your GTN 650xi doesn't know or care if the three A429 interfaces are made to a GSU 73 or a GAD 29. Just follow the wiring guidance on page 28-11 to make these A429 connections to your GSU 73.

The Connext interface between a GDU 4XX G3X Touch display is RS-232 and has NOTHING to do with the GSU 73 or GAD 29. Just use the wiring guidance on page 27-40 to add the single Connext RS-232 interface between your GDU 4XX PFD display and the GTN.

The MapMX RS-232 interface between the PFD and the GTN is the same on both systems, and again has nothing to do with the GSU 73 or GAD 29.

I also have a G3X system with GSU 73 which was upgraded to a G3X Touch system by changing the display and retaining the GSU 73.

Steve
 
Jimmy,

Your GTN 650xi doesn't know or care if the three A429 interfaces are made to a GSU 73 or a GAD 29. Just follow the wiring guidance on page 28-11 to make these A429 connections to your GSU 73.

The Connext interface between a GDU 4XX G3X Touch display is RS-232 and has NOTHING to do with the GSU 73 or GAD 29. Just use the wiring guidance on page 27-40 to add the single Connext RS-232 interface between your GDU 4XX PFD display and the GTN.

The MapMX RS-232 interface between the PFD and the GTN is the same on both systems, and again has nothing to do with the GSU 73 or GAD 29.

I also have a G3X system with GSU 73 which was upgraded to a G3X Touch system by changing the display and retaining the GSU 73.

Steve

Thanks Steve. I suspected the same as you have experienced. I just wanted some confirmation for other GSU73 users before I climb under the panel. You did that. Thanks again.
 
I've done a couple of these upgrades, it generally does take adding a 232 line from the GTN to the GDU470 to get the Connext connection as that usually was not installed. However, if you were smart when you wired the GTN, you installed but left the unused serial ports stowed for future use which makes it easy.
 
I've done a couple of these upgrades, it generally does take adding a 232 line from the GTN to the GDU470 to get the Connext connection as that usually was not installed. However, if you were smart when you wired the GTN, you installed but left the unused serial ports stowed for future use which makes it easy.

Understood. However, since Garmin failed to update the GSU73/GTN650 interconnect diagram to show Connext, you would have to be more than smart to know that adding the Connext RS232 for future upgrade is required. That's why I'm glad we are having this discussion to help future GTN installers.
 
Understood. However, since Garmin failed to update the GSU73/GTN650 interconnect diagram to show Connext, you would have to be more than smart to know that adding the Connext RS232 for future upgrade is required. That's why I'm glad we are having this discussion to help future GTN installers.

As Steve said, there is nothing new to the 73, the connext is GTN-GDU470 via 232.
 
I just did a similar upgrade last week, and was trying to figure out why you were having an issue, then realized I didn’t care about Connect, since I have a 430W instead of a 650 in the plane. Our upgrade was dirt simple - doing the new mounting holes took the most time, and that was only an hour of draping towels in the cockpit to catch the debris and using a die grinder and drill.

When you get it done, I predict you’ll love it - lots of “bang-for-the-buck” in the upgrade! (Probably moreso with a GTN….)
 
Garmin agrees:
I would use the diagram on page 28-11 for the ARINC conenctions between the GTN and the GSU 73, as well as the ARINC configuration guidance. In principle, yes they are the same as the GAD 29 (ARINC In/Out 1 and In 2) but that drawing shows the pin numbers and configuration for the GSU 73.

Because the Connext features are a function of the Touch displays, you should use the drawing on page 27-40 to wire the RS-232 connections between the GDU 470 and the GTN.
 
Jimmy,


The MapMX RS-232 interface between the PFD and the GTN is the same on both systems, and again has nothing to do with the GSU 73 or GAD 29.


Steve

The original GSU73 diagram for the MAPMX between the GDU37X and a GTN only shows an RS232 TX from the GTN. To function properly, the GTN and GDU470 need TX and RX so another RS232 has to be added.
 
I now have everything working correctly. I updated the first post in this thread to share my issues. Connext, Bluetooth with Garmin Pilot, Flight Plan transfer, etc. are now working perfectly.
 
I've done a couple of these upgrades, it generally does take adding a 232 line from the GTN to the GDU470 to get the Connext connection as that usually was not installed. However, if you were smart when you wired the GTN, you installed but left the unused serial ports stowed for future use which makes it easy.

I'm having a GNS-430W replaced with a GTN-650Xi. The existing panel has two GDU-370's and a GSU-25 (& a GTX-23ES, GDL-39R & GMC-305).

At the risk of telling the installer how to do his job, is the bold above something I should mention, in anticipation of a later GDU-370 to GDU-470 upgrade?

Any other considerations with this swap?
 
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I'm having a GNS-430W replaced with a GTN-650Xi. The existing panel has a GDU-370, GDU-375 and a GSU-25 (& a GTX-23ES, GDL-39R & GMC-305).

At the risk of telling the installer how to do his job, is the bold above something I should mention, in anticipation of a later GDU-370 to GDU-470 upgrade?

Any other considerations with this swap?

I think running the wire the extra wire will cost you a lot less now, than later. You never know when your GDU-370 might glitch. When I started this thread, Garmin did not have any GDU-370 refurb's to supply those that are dying. You might be forced, like I was, to upgrade.

$$
 
After putting some time on the new GDU-470's, I have some feedback:

Pro's: The case is more robust! No plastic to crack. It's an aluminum case and mounts much more securely. More versatility, and I like being able to share the flight plans between my Garmin Pilot and the GDU and GTN. You are able to customize the displays, even without going into configuration mode. For instance, I display a lot of waypoint, fuel and time information with two rows while flying cross country. Around the field I just display one row with g's.

Con's: The display seems smaller and dimmer. I would like to reduce the size, or eliminate some of the extra information in the headers. To display this information you sacrifice map and PFD size. Even with the brightness at full up, it's not as bright as the GDU 370/375's. The most bothersome issue is the max volume is much reduced on the GDU470. I've not changed anything, and Garmin ran out of ideas in the first email. I'd estimate the max volume is 1/3 less.

Worth the upgrade?.......no. I like the tactile feel of the GDU 370/375, especially in rough air. Touch screen can be tough in these conditions. I'd like to be able to have larger, brighter, and louder displays. And frankly, super disappointed that Garmin could not design the chassis to mount in the same holes.
 
Jim - Thanks for taking the time to report your transition experience. I have two original 370/375 screens and often consider an upgrade when missing things like the FF-to-650 flight plan transfer.

It seems like a lot of button pushing to handle the AP in IFR flight. I have had to hold the panel several times to even touch the buttons, and wondered about touch screen in same.
 
Interesting thoughts on the upgrade. I don't have any appreciable real world experience using either screens (370 vs. 470) but I'm surprised to read that you don't think the juice was worth the squeeze. Thanks for the feedback.

Regarding the extra wires during the 650Xi installation for the purpose of future proofing, what exactly would I need to specify to the installer?
 
After putting some time on the new GDU-470's, I have some feedback:
Con's: The display seems smaller and dimmer. I would like to reduce the size, or eliminate some of the extra information in the headers. To display this information you sacrifice map and PFD size. Even with the brightness at full up, it's not as bright as the GDU 370/375's. The most bothersome issue is the max volume is much reduced on the GDU470. I've not changed anything, and Garmin ran out of ideas in the first email. I'd estimate the max volume is 1/3 less.

Worth the upgrade?.......no. I like the tactile feel of the GDU 370/375, especially in rough air. Touch screen can be tough in these conditions. I'd like to be able to have larger, brighter, and louder displays. And frankly, super disappointed that Garmin could not design the chassis to mount in the same holes.

I've upgraded a number of these, including my own from 370's to 470's. The screen on the 370 was excellent, but the unit was so slow when it came to using the map that I hated that. It possibly might have been a little brighter, but I also love the touch screen. LCD screen brightness is viewing angle dependent to some degree, so keep that in mind when mounting. It is a bit of a learning process to anchor your hand to the screen using the "hand holds" but I've never really had an issue using the touch on any of the Garmin touch screens in bumpy air. Volume has never been an issue, using a GMA audio panel most of the G3X volumes are turned down to around 50-60% for the alert inputs, so that sounds like a problem with your installation.

I would NEVER go back to the old screens, the GDU4xx series blows the 370 series out of the water.
 
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The display seems smaller and dimmer.

I'm sure g3xpert will be along to confirm, but I happen to know that the display used in the GDU 470 is in fact brighter and higher-contrast than the one from the GDU 370, and is exactly the same size down to the millimeter.
 
Another thing to consider is the age of the product line and future serviceability - when I upgraded our -3 from 370’s to 470’s last year, Garmin really wanted the 370’s back so that they could harvest parts from them for their service department….. that tells me something about where they are in the lifespan of the 370’s…..
 
FD Mode Control

Jim - Thanks for taking the time to report your transition experience. I have two original 370/375 screens and often consider an upgrade when missing things like the FF-to-650 flight plan transfer.

It seems like a lot of button pushing to handle the AP in IFR flight. I have had to hold the panel several times to even touch the buttons, and wondered about touch screen in same.

Hi Bill,

If you do not install a dedicated autopilot controller like the GMC 507, you can control the autopilot by touching the autopilot annunciator (outlined in red below) on the G3X Touch. This brings up the AFCS control menu on the MFD portion of the display. You then make your desired selection, and press the BACK button to exit the menu.

ss.jpg

Thanks,

Justin
 
GDU 4XX Upgrade

After putting some time on the new GDU-470's, I have some feedback:

Pro's: The case is more robust! No plastic to crack. It's an aluminum case and mounts much more securely. More versatility, and I like being able to share the flight plans between my Garmin Pilot and the GDU and GTN. You are able to customize the displays, even without going into configuration mode. For instance, I display a lot of waypoint, fuel and time information with two rows while flying cross country. Around the field I just display one row with g's.

Con's: The display seems smaller and dimmer. I would like to reduce the size, or eliminate some of the extra information in the headers. To display this information you sacrifice map and PFD size. Even with the brightness at full up, it's not as bright as the GDU 370/375's. The most bothersome issue is the max volume is much reduced on the GDU470. I've not changed anything, and Garmin ran out of ideas in the first email. I'd estimate the max volume is 1/3 less.

Worth the upgrade?.......no. I like the tactile feel of the GDU 370/375, especially in rough air. Touch screen can be tough in these conditions. I'd like to be able to have larger, brighter, and louder displays. And frankly, super disappointed that Garmin could not design the chassis to mount in the same holes.


At full voltage, the GDU4XX displays are rated at a higher brightness value, in addition to higher contrast.

While not the same button-ology as the previous generation screens, most all system operations can be performed with the dual concentric knobs and 4 buttons, with an occasional touch required. It does take some getting used to.

Your audio problems are likely due to a installation problem. You can likely resolve the issue using either the audio level set on the display, or the input level on the audio panel/intercom.

Thanks,

Justin
 
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...it generally does take adding a 232 line from the GTN to the GDU470 to get the Connext connection as that usually was not installed. However, if you were smart when you wired the GTN, you installed but left the unused serial ports stowed for future use which makes it easy.

Regarding the extra wires during the 650Xi installation for the purpose of future proofing, what exactly would I need to specify to the installer?


I guess these are the serial connections that should be pre-wired to the GTN in anticipation of a future G3X touch upgrade?

Connext 1.jpg
 
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I guess these are the serial connections that should be pre-wired to the GTN in anticipation of a future G3X touch upgrade?

View attachment 40943

Looks correct to me. Also make sure the MapMX RS-232 connection is bidirectional... in many early installations this is wired as a receive-only connection, which will cause you problems later if you ever want to control the COM radio in your GTN from a GDU 4xx display.
 
Looks correct to me. Also make sure the MapMX RS-232 connection is bidirectional... in many early installations this is wired as a receive-only connection, which will cause you problems later if you ever want to control the COM radio in your GTN from a GDU 4xx display.

Thanks for the feedback, Matt. Good info.
 
I did resolve the volume issue. There was a GDU370 audio output that was doubled up with the new GDU470. Basically, the 470 was going to two places, instead of one. Once that was fixed, volume dramatically increased.

While the screen may be the same size, the horizon and map are smaller because more information is packed in the top and bottom of the screen. Garmin is slowly allowing the user to edit these screens and unpack it.

While it may be brighter, my 370 was easier to see and brighter in direct sunlight, just my experience.........yes, I know how to adjust it.
 
What about a GPS175?

I'm considering upgrading my GDU37X portrait screens to the GDU47X units. I use a GPS175, which accepts bluetooth flight plans from Garmin Pilot and the G3X uses them as an external flight plan. Will I need to change my Config Module, also?
 
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