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Interesting G3X behavior after Nav Strobe 7.5A fuse blown

S

subpar_bucker

Well Known Member
Had an interesting event happen today while flying. A few minutes into the flight both G3X's went completely dark. Engine kept running, and I was able to land shortly thereafter with the help of my instructor.

Once on the ground we noticed that the Nav Strobe 7.5A had blown. I have not figured out that issue (replaced the fuse and the lights work fine). However, while troubleshooting on the ground we were able to reproduce the G3X issue:

https://www.youtube.com/watch?v=vY0rwbNXLXg

It's unclear to me why pulling that fuse causes the screens to auto-dim like that, but thought it was worth sharing with the collective.
 
subpar_bucker said:
Had an interesting event happen today while flying. A few minutes into the flight both G3X's went completely dark. Engine kept running, and I was able to land shortly thereafter with the help of my instructor.

Once on the ground we noticed that the Nav Strobe 7.5A had blown. I have not figured out that issue (replaced the fuse and the lights work fine). However, while troubleshooting on the ground we were able to reproduce the G3X issue:

https://www.youtube.com/watch?v=vY0rwbNXLXg

It's unclear to me why pulling that fuse causes the screens to auto-dim like that, but thought it was worth sharing with the collective.
Click to expand...


If you look at the full wiring diagram you will find that that fuse also provides power to the dimmer circuit. Pull that fuse and the G3X thinks it is being told to go to full dim.
 
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I would suspect the screen dimming is tied into the nav lights, if the nav circuit shorts the screens are following that voltage and dimming.
You can program the G3X dimming lower level so that if the voltage goes to zero the screen reverts to full brightness to avoid that situation.
 
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Screen Dimming

Mr. Bucker, ;)

Thanks for sharing your experience, I will bring this up with Engineering tomorrow.

The answer may very well be Walt's suggestion of changing the lower end of the dimmer curve to revert to full brightness in this situation. After reviewing the RV-12iS configuration documentation in the "G3X Pre-Sets Read-Me" file, a screen brightness failsafe mode should already be configured.

EDIT - Adding additional information:
After watching the video it appears the screen brightness control is working as intended.

If you have configured your G3X system as per the "G3X Pre-Sets Read-Me" document, pulling (or blowing) the NAV/STROBE fuse causes the G3X Lighting Bus input to go below the "Lighting Bus Off Threshold Input" setting of 0.5V, at which time the screen backlight brightness control falls over to Photocell control.

It's possible that the setting of 5% for "Light Sensor Brightness Min" is too dim for some people and these settings can be tweaked to your liking. Please refer to the G3X Installation Manual section 30.4.19 "Backlight Configuration Page" and the RV-12iS "G3X Pre-Sets Read-Me" file. https://www.vansaircraft.com/wp-content/uploads/2021/04/G3X-PRE-SETS-READ-ME-Rev14.pdf

Mr. Bucker, It's great to see you are flying your RV-12! Let me know if you need any troubleshooting assistance.
.
 
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It used to be pretty common that the dimmers were tied to the nav light switch, as we never dim until evening when the nav lights come on. Mine are wired that way; nav off = 12v to dimmer (100% brightness), nav on = 12v now runs through a voltage divider and a linear relationship between volts and brightness.
 
subpar_bucker said:
Once on the ground we noticed that the Nav Strobe 7.5A had blown. I have not figured out that issue (replaced the fuse and the lights work fine).
Click to expand...

The strobes will spike/peak at 9.1A; I had the same issue. Replace the 7.5A with a 10A and you will never have this trouble again.

Ryan Edmark at AeroLED was going to take up changing the POH and documentation for 10A instead of 7.5A with Van's Engineering after I had this issue in October 2021.
 
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Tony's point about the README file was correct. I had NOT FOLLOWED all of the configuration steps regarding setting the brightness levels there. I had a chance to do that over the weekend and now pulling the fuse results in a visible G3X. If you are interested in the details you can look at this album:

https://photos.app.goo.gl/6cafkHdYgZqHuvjUA

Apologies for failing to RTFM. I thought I had performed this step when the airplane was still at the house, but obviously I had not.
 
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