Chosen Solution
Hi Guys. Im having the headache with Asus X405U. Whats going on is that the screen is black, however laptop boots normally and works smooth on external monitor. I’ve bought new display cause i was sure it is broken display, connected it and its still the same. Since that i have checked everything, RAM is soldered to the mainboard and there is no other memory module, i removed internal battery and did CMOS reset by pressing power button for 60 sec. I’ve been trying to find lid switch but unfortunately couldn’t locate it, so i went to power options and disabled it in the settings. Still no luck. I was also able to get to bios via external monitor, reseted it and been playing with lid settings there - no luck.
What i find weird is that sometimes display shows up for 3 sec and goes black again. It happened to me when i was pressing random keys on the keyboard. Same happened when i disconnected keyboard while the laptop was running. I tried to replicate it again but no success. One thing that comes to my mind is LCD flex cable but it seems good and as i mentioned above sometimes display lights up. I tried to bend it and move - there was not even a glipse.
Did anyone had similar issue? Im seriously loosing patience.
@jayeff SOLVED I did check everything literally and i was close to give up. The last thing i had in mind was that maybe gpu is faulty however i have never experienced issue with gpu when external monitor works fine. I removed motherboard, removed heatsink, checked thermal paste under CPU and GPU (its integrated) everything seemed ok. I decided to reflow it using hair dryer (i know its $@$*!& approach but im not in my country and have no tools here). Left it for 20 mins with the highest temp. After reassembling it turned on with lcd display working like a charm. Well for another few hours…. Then i got same problem again. It was 4 long days but im happy now. At least im sure what was the issue and will try to reball CPU/GPU unit properly. Im sure that many of the posts i found online about faulty Intel HD Graphics drivers and people not being able to fix it for months could be related to GPU units itself. Hope my post can solve some people headaches.
Hi @dzet , Can you see images on the laptop screen when using a torch held at an angle close to the screen? They will be very faint if they are there so trying this in a darkened room may help. If you can see images then there is a backlight problem. There is always power supplied to the screen for the backlights and it is turned on/off in the LCD panel by a signal voltage on/off the BL lead in the cable from the motherboard. If you still have the old display check the panel model number (found on the back) and search online for (insert panel make and model number) pinout to hopefully find the datasheet for the panel. This will tell you which wires the LED backlight power feed is on so that it can be tested (on a lot of 30 pin cables it is pins 26-29 and the BL is on pin 22 - but don’t take this as what it is on yours). Also try pressing on the hinge where the cable passes through from the motherboard to the lid and check if this causes the backlights to turn on/off etc
