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GTN 650 backlight problem

jthocker

Well Known Member
3 of us at Team AD have 650s and all run into the same problem at night.
We can get our displays to dim in the hangar after configuring from setup mode, by placing our finger over the photocell. When we actually go out and fly at night, the display stays bright and will not dim!
Help!
 
Mine is tied to a dimmer knob so no direct experience, but IIRC, there is a "slope" adjustment in addition to enabling the photocell. Is it possible it's dimming, but just not aggressive enough?
 
I have a 650 as well. I took off at just before dawn one day in the way to the paint shop and it was dimmed fine, but as the sun came up it didn't get any brighter. Eventually cycled the power to it and it was bright once it rebooted. Haven't called the Garmin experts yet, because the plane is being painted at present so I don't have access. Will watch this thread.
 
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No problems here but it did take a bunch of tweaking the settings to get it the way I like it.
 
You probably need to go and actually tweak the setting of your lighting setup to get it specific to your plane and installation. In the "Photocell Configuration" and "Lighting Configuration" pages you can change and configure things like:

Minimum Level
Maximum Level
Response Time
Slope
Offset
Key Backlight Cutoff
Photocell Transition
Photocell Curve
Day Mode Operation
Night Mode Operation

You can find all those various settings along with pictures on how to configure them in the installation manual...and you can set it to work however you personally prefer, and however it'll work best in your specific installation and location in the plane. I hear this issue often, and almost always the answer is to go configure it to work in your plane. You wouldn't want a box that dims itself exactly the same whether installed under a bubble canopy, inside a jet, helicopters with NVG, etc.. This is another one of those things that you actually need to setup to get perfected.

Cheers,
Stein
 
Starting point

Is there a place I can look to see what are the typical setting values for the parameters Stein outlined above for the back-light photocell setup?

Thanks if anyone has there's dimming correctly and could post the settings.

Steve
 
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