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GAD-27 Dimming

D

Dad's RV-10

Well Known Member
I've got to decide how to allocate the three dimming circuits on the GAD-27. The panel has two GDU-460's, a GTN-750, GMA-245, GMC-507 and a G5. From looking at the manual, it looks like the G5 lighting is pretty much controlled by its internal photocell.

From practical experience, does having ALL instrument lighting on a single dimmer work in the real world? In other words, can proper lighting balance be achieved if the display/screen brightness and the radio background/button lighting are controlled together?

Or should we allocate one dimmer to control the GDU and GTN display brightness and another to control radio button/backlighting?

I'm inclined to keep the display brightness and button/background lighting on separate dimmers and use the third dimmer for cabin lighting.
 
I only used 2 of the GAD 27 controls 1. Switch Backlight, 2. Glareshield LED strip.

After 300 hours, I think I would add a footwell or cargo/cabin light.

The rest of the stack/radios/displays use internal photo cell.
 
I used all three. A) was for instruments like GDU460,s GNX375, etc; all the instruments that allowed dimming.
B) was for the panel LED strip that is attached to the underside of the glare shield.
C) was for the illumunation of the switches. My rocker switches are black have LEDs inside that illuminates the white lettering.

Please note: the dimmer for the GDU, GNX, etc, when turned all the way left, reverts to the internal photocell, so it defeats the dimmer pot. This is really helpful when things are happening fast and furious setting up for approach, or just being lazy.

The glare shield lighting is really important at night. I leave it low for Cross countries, but then turn it up for approach so i can quickly see where at the knobs are at.
 
IMHO this is a ‘personal preferences’ question. Everything on one dimmer, some displays are likely to be brighter or dimmer than optimal while others are just right. But, you don’t have to fuss with multiple knobs either. Same for internal photocell. It comes down to will you tolerate less than perfect lighting for operational convenience, or not? I use a mix myself (external knob for efis, second external knob for glareshield, everything else on internal photocells.)
 
BobTurner said:
Everything on one dimmer, some displays are likely to be brighter or dimmer than optimal while others are just right.
Click to expand...

Theoretically, "some too bright, some too dim" should be avoidable by properly adjusting the lighting mapping parameters.

That's what I'm asking; From personal experience, have any of you been able to successfully map the variable lighting parameters within the G3X and GTN configuration pages to result in liner response of both the screen brightness and button backlighting across multiple devices (GDU, GTN, etc) on a single dimmer?

Or it it difficult (or impossible) to achieve?
 
Dad's RV-10 said:
Theoretically, "some too bright, some too dim" should be avoidable by properly adjusting the lighting mapping parameters.

That's what I'm asking; From personal experience, have any of you been able to successfully map the variable lighting parameters within the G3X and GTN configuration pages to result in liner response of both the screen brightness and button backlighting across multiple devices (GDU, GTN, etc) on a single dimmer?

Or it it difficult (or impossible) to achieve?
Click to expand...
I mapped mine pretty easily. It is not hard and took me about two hours. If it is an all Garmin panel, the intensity verses voltage was pretty much spot on the same for each. I think I had to make one minor tweak because one of the items was too dim.

In practice, I think your eyes accommodates the varying intensity fairly well. I notice it when I take a picture of the panel with my iphone. But that could be due to polarization too, I don't know exactly.
 
PilotjohnS said:
I mapped mine pretty easily. It is not hard and took me about two hours. If it is an all Garmin panel, the intensity verses voltage was pretty much spot on the same for each. I think I had to make one minor tweak because one of the items was too dim.

In practice, I think your eyes accommodates the varying intensity fairly well. I notice it when I take a picture of the panel with my iphone. But that could be due to polarization too, I don't know exactly.
Click to expand...
I recently fired up new panel for the first time. 2) G3X screens with gtn 750 and auto pilot. 3 dimmers.
1- buttons
2- avionics
3- floodlight.
Question is: both G3X screens, gtn 750 and auto pilot are on the avionics dimmer. When I turn up the brightness the 2) g3x screens turn brighter and the 750 and auto pilot get dimmer. Anyone ran across this and figured it out?
Thxs
 
Mfozzi said:
I recently fired up new panel for the first time. 2) G3X screens with gtn 750 and auto pilot. 3 dimmers.
1- buttons
2- avionics
3- floodlight.
Question is: both G3X screens, gtn 750 and auto pilot are on the avionics dimmer. When I turn up the brightness the 2) g3x screens turn brighter and the 750 and auto pilot get dimmer. Anyone ran across this and figured it out?
Thxs
Click to expand...
Yes, this happened to me too. I ended up using internal photo eye (avionics dimmer all the way left) and turning up the glare shield lights so the photo eyes think it is dusk. I need to dig into this too because I don't remember it doing this before. Maybe I had a reset????
 
PilotjohnS said:
Yes, this happened to me too. I ended up using internal photo eye (avionics dimmer all the way left) and turning up the glare shield lights so the photo eyes think it is dusk. I need to dig into this too because I don't remember it doing this before. Maybe I had a reset????
Click to expand...
Thanks for input. Going play more with tonight.
 
I am thinking i pulled some wires away from the terminal strip that has the lighting bus fanout. That seems to be the only explanation. Will check later this week i have lost lighting bus control of gmc500, gma,245, and gnx 375, but still have it for g3x

Unless this was affected by the last software update?
 
Ok it appears my trouble with instrument lighting is the lighting control input in my panel wiring.
My gnx375 is not showing the lighting input voltage varying when the g3x are dimming.

Since 3 instruments are affected, either i am overloading the voltage input (10 ma max) or my ground ( lighting low) is now open.
 
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PilotjohnS said:
Ok it appears my trouble with instrument lighting is the lighting control input in my panel wiring.
My gnx375 is not showing the lighting input voltage varying when the g3x are dimming.

Since 3 instruments are affected, either i am overloading the voltage input (10 ma max) or my ground ( lighting low) is now open.
Click to expand...

Keep us posted.
 
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