ASUS G2S Backlight Randomly Shuts Off

I did a search on this site and the internet and could not find a close enough match to the problem I have been experiencing. Note that I have sent this computer in 3 times for different problems. The last time I sent it in, they switched it with someone else's by accident and it took 2 weeks to get that problem resolved. I have no wish to RMA this computer ever again, and I am way past warranty anyway.

Every now and then (usually when the computer has been on for an hour or so) the backlight (not the screen) will turn off. To get it back on I simply press FN+F7 two times (one to turn it 'off' and other other back on). This usually fixes the problem, but then it will turn off again a couple minutes later. It is completely random, sometimes a couple times in rapid succession. It doesn't seem to matter what position the screen is in or how bright it is. I am thinking it is a loose connection cable between the two halves of the laptop. I asked ASUS about it in my RMA when they replaced my Motherboard. It seems they replaced the entire monitor half of my computer, but the problem still persists.

As a side note: It seems to worsen/happen more frequently when I have something such as a portable hard drive in and it almost unbearable when it is not plugged into the wall.

Let me know what you think it might be, and if it is something that I could get at myself. I've repaired only desktop computers before, but I'm not afraid to take this system apart (the repair team from ASUS already removed the warranty stickers).

 

There are several possible causes:

1. Problems with the power management software/drivers. Try removing the entire ATK suite of drivers and applications, and reinstalling the latest versions from support.asus.com. Also update your BIOS to the latest version, for good measure.

This possibility is supported by the fact that the problem is worse when the computer is not plugged in -- since a different power management profile is applied on battery power, and this different profile may make the problem worse. A more radical fix would be to reinstall Windows from scratch. To check if it is indeed a software problem, try running the computer under a Live Ubuntu CD for a while, and see if the problem appears. If it does, it's most likely in the BIOS/hardware.

2. The mechanical switch that tells the computer the lid is closed is bad, and makes contact when it shouldn't. Solution: replace or disable switch (requires disassembly). I do not think turning off the backlight on lid close is something that can be controlled by software, as to my knowledge it is BIOS controlled and not user changeable on ASUS laptops.

3. The inverter is going bad and can't drive the backlight reliably anymore. Solution: replace inverter. See the Info BoothFAQ for possible sources for the new inverter. It is a cheap part BTW, under 20 dollars.

4. The backlight itself is bad. Solution: replace LCD (requiring disassembly) or only backlight within LCD (much more difficult, requiring extensive disassembly). Large costs, if this can't be solved from warranty I would perhaps suggest a new laptop instead, also depending on your funds.

5. Bad/partly interrupted or shorted connection cable between mainboard-inverter, or inverter-screen. How to test: moving the laptop lid would probably trigger the problem, and may fix the problem once it has occurred. Solution: replace cables (cheap like the inverter, requires disassembly).

I do not have a clear idea on how to isolate among 2-3-4, unfortunately, except by actually changing the affected parts...

I would maybe suggest trying to isolate a software problem first, see my suggestion under 1, and if not, order the inverter + cables and exchange them.

Hope this helps.

 

Those are some excellent problem suggestions.

I have restored the computer to factory condition, so I doubt it is a software issue. I may try removing power management software, but it doesn't seem to matter if I run it in battery mode or high performance - as long as it's plugged in. I will try it anyways and get back to you. ASUS replaced the entire top portion (including LCD and backlight), so I'm sure it isn't that. I'm thinking the cable between the two halves. I have never seen what an inverter looks like or what it does, but I'll do some research. Any chance if you know it can be reached without extensive disassembly? Thanks for all your help.

 

The inverter is a relatively small circuit board, usually located in the bezel of the screen. Check some of the disassembly guides on the Info Booth, you will find pictures of how an inverter looks like. You need to disassemble the LCD bezel to get at it, it's a medium-difficulty disassembly job as far as laptop disassembly goes.

If you are sure the entire top was replaced (not just the LCD itself) then it's probably not at fault, and the power management software, lid-closed detection switch or interrupted cable are more likely to be the problem.