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G3X Displays Dim When NAV/STROBE Fuse Blows

Amadeus

Well Known Member
Flying RV-12iS with Garmin dual G3X system. Occasionally the NAV/STROBE fuse will blow and when it does the G3X displays go dark. Are the G3X screens routed through the NAV/STROBE fuse? It doesn't seem so as the autopilot continues working and I can twist the heading bug knob to change direction even with dark screens. Also, once the fuse is changed out for a new fuse the G3X displays light up again without the units rebooting. They just pick up as if I had turned down the dimmer knob then turned it bright again.

I've pulled both wingtip AERO lights and checked the wiring for any nicks in the insulation but both sides look perfect. Any suggestion on what I should check next for the source of the fuse blowing?
 
This is not possible without a major wiring mistake in your power distribution.

With the little bit of information you provided, I’d guess you have a common fuse feeding your Nav/Strobe and EFIS. I would also guess the power goes through this common fuse, then to your EFIS fuse. In other words your EFIS fuse is in series and downstream of your Nav/Strobe fuse.

Or I suppose you could have some weird connection between your Nav/Strobe and your G3X for indication - but why do that?? Perhaps you have a dimmer feed to the G3X coming off your Nav/Strobe fuse.

Ring out your wiring, document it all, then fix.

Carl
 
my guess is that your G3X dimmer control is tied to the nav/strobe fuse bus. If you lose the 12V bias on the dimmer voltage divider, the G3X will see basically ground on the dimming input, i.e. minimum brightness setting. Change the G3X dimmer source to "photocell" and see if it resolves the screen brightness.

Check your wiring diagram, if you have an EFIS dimmer control, to see what feeds it. If it is the nav/strobe circuit, you may want to change it to the avionics power buss.
 
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