Laptop LCD display brightness issue

[andyred]

Hello All,

I encountered these days an issue which I've never seen before and I've repaired a couple of computers so far.
The LCD display on a Asus N76VZ laptop is always on maximum brightness. Replaced the video cable with a new one, checked if this isn't an OS issue by reinstalling the same OS, another OS (Windows 10, Win 8, Win 7), in neither the brightness cannot be adjusted. Is like the OS is seeing the LCD doesn't have adjustable brightness. There is no OS setting either which is causing this.
So it remains the hardware. I know when a display or inverter are going bad, display usually gets dim not stuck on maximum brightness.
Perhaps some of you encountered this before and can provide some advice how to fix it.
Thanks in advance

[ktmmotocross]

Re: Laptop LCD display brightness issue

did u have brightness slider in power control page?

[caspian]

Re: Laptop LCD display brightness issue

find (Fn + key) for brightness adjustment in this laptop. then try to check whether it can decrease brightness or not.

[andyred]

Re: Laptop LCD display brightness issue

Nothing works, it's not settings/OS related (combo keys, sliders do not work).
OS was reinstalled as well and it's the same

[caspian]

Re: Laptop LCD display brightness issue

enter the Bios page and see how is the brightness.

[andyred]

Re: Laptop LCD display brightness issue

maximum brightness in bios as well

[SMDFlea]

Re: Laptop LCD display brightness issue

Did you install the ATK ACPI driver .

[andyred]

Re: Laptop LCD display brightness issue

Yes it is installed (latest version .40). Again this is not software related since I have the maximum brightness in BIOS as well

[caspian]

Re: Laptop LCD display brightness issue

It might be a great help if you ask the laptop owner when the problem started to happen. I mean: after what operation on the laptop.

[SMDFlea]

Re: Laptop LCD display brightness issue

Did you replace the screen,or have you tried another one ,have you tried a bios update .

[ktmmotocross]

Re: Laptop LCD display brightness issue

did u have brightness slider in power control page?

[andyred]

Re: Laptop LCD display brightness issue

@caspian a week ago out of the sudden, the display stopped working, it was the vga cable (two wires broken). I've replaced the cable with a new one but I have this issue. Tested with another known working cable and it's the same.

@SMDFlea latest BIOS available installed, screen was not replaced don't have another screen to test with

@ktmmotocross Windows 10 v1809 doesn't have a brightness slider in power control page as per design

[Jesse James]

Re: Laptop LCD display brightness issue

I know you said its not os problem but this worked for me in the past

go to display adapters. open the tab and right click on the graphics card thing that comes up update driver software browse my computer let me pick select basic display adapter do the same thing again but revert it back to the previous graphics card Basically resetting it, it worked for me. Good luck.

[andyred]

Re: Laptop LCD display brightness issue

@Jesse James tried absolutely eveything software related...no go

[andyred]

Re: Laptop LCD display brightness issue

Any other ideas guys?

[SMDFlea]

Re: Laptop LCD display brightness issue

@caspian a week ago out of the sudden, the display stopped working, it was the vga cable (two wires broken). I've replaced the cable with a new one but I have this issue. Tested with another known working cable and it's the same.

@SMDFlea latest BIOS available installed, screen was not replaced don't have another screen to test with

@ktmmotocross Windows 10 v1809 doesn't have a brightness slider in power control page as per design

So, 2 wires were broken, they may have shorted together and damaged something. To see if the fault is on the motherboard you need the Boardview, check the LVDS/PWM area. Try another screen or check the screens PCB for any obvious burnt parts,shorts .

[andyred]

Re: Laptop LCD display brightness issue

Unfortunately I could not find any complete Boardview for the Asus N76VZ model. I could not see any obvious burnt parts or shorts neither on the motherboard, neither on the screen.

[SMDFlea]

Re: Laptop LCD display brightness issue

You can ask for a boardview in the Schematic Requests sub-forum, hopefully someone will have it and post it,if not ,you will have to buy one.

[raajkumar]

Re: Laptop LCD display brightness issue

Is it responding or showing OSD when you press the hotkeys for Brightness ?

[andyred]

Re: Laptop LCD display brightness issue

@raajkumar it's the same on windows 7 or in the bios. It shows the brightness control when you press the keys, but min or max makes no difference, is still maximum brightness