Question Laptop screen went black out of a sudden

[prm1]

Hi guys, I'm new here and really hope I can get some help

I was using my laptop normally (Samsung np-sa31, Bremen - M motherboard), I turned it off, by pressing the power button and then closing the lid if I remember correctly since I was in a hurry.

After coming back to the device, the screen just wouldn't turn on! It just stayed black.

I tried everything. Messed around with the BIOS, reconnected the LCD cable, repositioned the RAM sticks and tried to run it with only one of the sticks, removed the CMOS battery and then placed it back, tried to clear static via power button, and much more, INCLUDING buying a whole new screen! The same problem still persists.

The laptop is fully working when connected to an external display via VGA cable, you can see everything on the screen when you flash with a flashlight on it (same for the original LCD and the brand new one I bought).

I have no idea what's wrong. I fully disassembled the laptop and I will add imaged of the motherboard, to me, nothing seems out of place and no fuses are burnt (the heat sink was removed for the sake of the photo), but maybe you guys will know what to look for and I'm just missing something.

https://pasteboard.co/ogkZ1xfYLAkd.jpg

https://pasteboard.co/P9Zqc2IouPl1.jpg

Thanks!

 

[helpstar]

Which laptop model is it exactly?
Did you replace the CMOS battery with a new one yet?

You wrote that the external monitor is working fine, but is it working with the flashlight only too or is it just standard ok?
If only the integrated displays show no light, the backlight is faulty or the connection to it. Did you replace the LVDS (internal display cable) cable?

 

[prm1]

Which laptop model is it exactly?
Did you replace the CMOS battery with a new one yet?

You wrote that the external monitor is working fine, but is it working with the flashlight only too or is it just standard ok?
If only the integrated displays show no light, the backlight is faulty or the connection to it. Did you replace the LVDS (internal display cable) cable?

Hi, thank you for replying.

This is a Samsung np-sa31, there's not much about it online.

I did not replace the CMOS battery, I just reseated it. There are no signs that the battery is dead, could it really be the cause?

Sorry if I wasn't clear, the external monitor works just fine and the laptop can be used with no issues. The issue is with the integrated displays, both with the old one and the new one I got, you can only see what's on the screen using a flashlight.

I didn't replace the LVDS cable.

 

[helpstar]

is the backlight inverter of your laptop an extra board? might be faulty if both displays are working with a flash light
the CMOS battery could always be a problem, but since the external monitor is working well, should be fine though
my thinking would be the cable to the monitor, it´s the most bend part in a laptop

 

[prm1]

is the backlight inverter of your laptop an extra board? might be faulty if both displays are working with a flash light
the CMOS battery could always be a problem, but since the external monitor is working well, should be fine though
my thinking would be the cable to the monitor, it´s the most bend part in a laptop

It's an extra board, but the new display I got came with it. I just noticed that there are a few burnt fuses, however I'm not sure. I will add the MB schematic and the photos. Please take a look. Are those burnt and are they related to the backlight power? Based on the schematic all the features that those fuses responsible for are still working so I'm not sure.

https://pasteboard.co/4HPSRBWnMztr.png

https://pasteboard.co/Koj1vLHUwwED.png

https://pasteboard.co/LjXjNzKfdywk.png

https://pasteboard.co/IhAddmCzJnTm.png

https://drive.google.com/file/d/1Ck3IUzfLsWUSD8Wg_dWP81AzKKqHVKaY/view

 

[helpstar]

did you replace the cable yet?

 

[Reynod]

My old Toshiba went the same way and it was the cable between the mobo and the screen - the cable passes through one of the screen hinges and it was damaged.

 

[helpstar]

The "fuses" are only LEDs on the board

 

[Garyk_]

Did you notice any physical damage or unusual behavior before the screen stopped working?