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  #1  
Old 08-10-2022, 01:09 AM
agent4573 agent4573 is offline
 
Join Date: Aug 2019
Location: Mountain view
Posts: 618
Default G3X and Dynon minimum brightness setting

Friend told me about a strange "failure mode" common to both manufacturers, was looking to get some advice. The main setup is a PFD/MFD with a TCW avionics backup battery. The screens are setup to use a dimmer knob to control brightness. Not sure what the dynon is using, but the g3x is wired through the gad27 for lighting control.

Failure scenario: power failure at night. you lose the gad27 lighting control and the screens revert to the ambient sensor but are still being powered by the backup TCW battery. We tested in a dark hanger and they dim to 3% and are barely readable even in the dark. Is there a setting somewhere to set minimum screen brightness when using the sensor?

The initial emergency response we thought of was to find your phone, turn on the flashlight and shine it at the sensor, or Menu-Menu-Setup-Display-Manual, then Increase brightness. During an emergency on a screen that's super dark, that's a lot of button presses during, for me, a night time engine out scenario. Discuss....
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Last edited by agent4573 : 08-10-2022 at 01:16 AM.
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  #2  
Old 08-10-2022, 07:55 AM
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Walt Walt is offline
 
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Yes you can raise the minimum brightness level in the setup menu.
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  #3  
Old 08-10-2022, 08:08 AM
lr172 lr172 is offline
 
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Don't know about the 27, but on the regular G3X, you feed a variable voltage source into the lighting bus input and then you build a configuration that relates voltage to brightness level. There is a provision for setting a different brightness below a threshold, like 2 volts. Therefore, if the ship bus is providing the variable voltage and you lose that source, the voltage will drop to 0 and the G3X will provide the brightness programmed for that (should be a setting that would work for both daylight and night). Not perfect, but definitely not flying blind. If it is too bright or too dim, you can go into setup and change it to manual mode after the failure. Can't remember if you have to go into config mode to do that, but think you can get to it via the menu button.

In my case, 0 volts is full brightness and source is different than that of the EFIS. So in the power failure scenario, it goes full bright. That is no big deal at night outside of landing phase, so would just go into setup and change it to manual dimming. Just DO NOT create a scenario where it can go very dim, as you will NOT be able to navigate the menu in full sun. My GRT is set up for dimming via the menus and if I forget to raise it after a night flight, I an unable to see the screen on the next daytime flight. GRT is simple enough that I remember the button presses; Now way for that on the G3X.

Larry
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Last edited by lr172 : 08-10-2022 at 08:21 AM.
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  #4  
Old 08-10-2022, 09:16 AM
agent4573 agent4573 is offline
 
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Cool. I've set the brightness vs voltage curve, but I didn't find all the options for where the light sensor overrides or how to set the minimum light sensor brightness. I'll go play around more in the config menu and start adjusting all that. Thanks
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  #5  
Old 08-10-2022, 09:22 AM
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g3xpert g3xpert is offline
 
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Location: Olathe, KS
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Default GAD Cockpit Lighting

Quote:
Originally Posted by agent4573 View Post
Friend told me about a strange "failure mode" common to both manufacturers, was looking to get some advice. The main setup is a PFD/MFD with a TCW avionics backup battery. The screens are setup to use a dimmer knob to control brightness. Not sure what the dynon is using, but the g3x is wired through the gad27 for lighting control.

Failure scenario: power failure at night. you lose the gad27 lighting control and the screens revert to the ambient sensor but are still being powered by the backup TCW battery. We tested in a dark hanger and they dim to 3% and are barely readable even in the dark. Is there a setting somewhere to set minimum screen brightness when using the sensor?

The initial emergency response we thought of was to find your phone, turn on the flashlight and shine it at the sensor, or Menu-Menu-Setup-Display-Manual, then Increase brightness. During an emergency on a screen that's super dark, that's a lot of button presses during, for me, a night time engine out scenario. Discuss....
Good Morning,

The DC Lighting outputs of the GAD 27 are what are used to control the brightness of your G3X Touch display. A variable DC voltage (output voltage to the G3X Touch is based on the lighting control input voltage to the GAD 27) is used to vary the brightness of the display. How the DC lighting output reacts to changes in GAD 27 input voltage changes, is modified in the Cockpit Lighting menu in configuration mode.

What happens when that DC lighting voltage is absent (GAD 27 fails) from the G3X Touch lighting bus input, is controlled in the Backlight configuration menu. Details on these settings are included on page 35-132 of the G3X Touch Installation Manual. You may want to review your settings for Light Sensor Brightness, Lighting Bus Minimum Threshold, and Lighting Bus Off Threshold. The lighting bus minimum threshold allows you to assign the bottom end of the display brightness curve to a specific DC input voltage. One option you have is to increase this bottom end, so that if the DC input ever falls to zero, your brightness only ever falls to 20% for example.

Another way to handle this situation is to make use of the Lighting Bus Off Threshold. You assign a voltage to this setting, and if the lighting bus input voltage falls below this value (GAD 27 fails and provides 0 volts to the G3X Touch), the system will revert to using the photocell.

The light sensor brightness setting allows you specify a range for display brightness while the system is operating on the photocell. You can raise the lower end of this range to avoid having the screen ever dim beyond an acceptable level.

As you can see, there is a lot of customization available here. Without looking at your current settings, we can't say for sure what you may want to change, but if you would like to send us a screenshot or picture of your settings to G3Xpert@Garmin.com, we can review them for you.

Thanks,

Justin
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Last edited by g3xpert : 08-10-2022 at 01:12 PM. Reason: Typo/Clarity
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  #6  
Old 08-10-2022, 10:04 AM
agent4573 agent4573 is offline
 
Join Date: Aug 2019
Location: Mountain view
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Quote:
Originally Posted by g3xpert View Post

What happens when that DC lighting voltage is absent (GAD 27 fails) from the G3X Touch lighting bus input, is controlled in the Backlight configuration menu.
Thanks,

Justin
Thanks, that's the info I was missing. I was looking all over the cockpit lighting menu and didn't see the options I needed. I'll go adjust the backlight settings.
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  #7  
Old 08-10-2022, 03:31 PM
Reaver Reaver is offline
 
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I'm the friend that was working with him on this. Does anybody know where the equivalent setting is for the Dynon Skyview?
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