Asus X555 U backlight problem

[shybear]

hi,
I've a really weird problem with this laptop.
It works properly with DC power but when I disconnect it, LCD backlight shutdown.
It happen already when you're in BIOS setting and laptop doesn't power off just the screen, even if its dark, is still visible and it appear if I attach again DC power.
Mainboard is X555UJ rev.2 and even if I didn't find schematic I find boardview that I attach here for reference.
This model has Intel integrated graphic card and LCD is attached on J4502.
+LED Vcc is 19V with DC power always inserted and 8V only with battery that decrease to 7,4V if I power on laptop.

I suppose that pin 34 (BL EN C) that I think it could mean "backlight Enable Circuit" doesn't get power just from battery.
On this point there is D4501 (tested OK) and R4504 that measure 1K.
I've already dumped and next updated BIOS to last release so it make me suppose it could be an hardware failure on mainboard.
This issue doesn't happen on DV-I port but there is something strange.
In Windows 10 even if I set to duplicate or extend screen when the external monitor is attached LCD is completely black, no matter if laptop DC jack is inserted.
Battery works fine and charge at 100%.

MOD Edit: Boardview - https://www.badcaps.net/forum/showthread.php?t=91136
.

[mcplslg123]

Re: Asus X555 U backlight problem

There are few articles on this issue already in this forum. First try replacing the coil near backit circuit of laptop screen. Dont measure, just replace it and check again.

[shybear]

Re: Asus X555 U backlight problem

There are few articles on this issue already in this forum. First try replacing the coil near backit circuit of laptop screen. Dont measure, just replace it and check again.

This one in pictures or are you talking of big coil PL8601 marked 1R0 ?

[mcplslg123]

Re: Asus X555 U backlight problem

@shybear, not on mb. Pull out the screen and look neat inverter circuit on the back of screen itself. The coil is located close to backlit connector and most probably marked "100"

[shybear]

Re: Asus X555 U backlight problem

@shybear, not on mb. Pull out the screen and look neat inverter circuit on the back of screen itself. The coil is located close to backlit connector and most probably marked "100"

Yeah I followed the other thread
https://www.badcaps.net/forum/showth...cklight&page=3

and I sorted its on display. I exchanged with an other broken Innolux panel I had here and now it works even if sometimes with battery flickers so I suppose this other coil isn't so good healthy.

On an Au Optronics I found an other coil (L401) marked 6R8 do you think is it safe to try to use it or is it better to looks for 10uH ?

[mcplslg123]

Re: Asus X555 U backlight problem

You need exact 10uH coil.

[shybear]

Re: Asus X555 U backlight problem

You need exact 10uH coil.

It's fine, anyway problem solved
Really thanks for support

[emicronet]

Re: Asus X555 U backlight problem

Thanks

[Christian0734]

It's fine, anyway problem solved
Really thanks for support

Hello, you mention that the problem has been solved. How did you resolve it? Was it by changing the coils on the screen's board? I am interested because I am facing the exact same issue with an ASUS X553M. Sharing your solution could greatly help the community. Thank you for your response

[RethoricalCheese]

The solution has been repeatedly shared already. Change the inductor.