Display assembly diagram

Here is a simple diagram that will help you to understand how a notebook display assembly works and how an image appears on the screen. I’m not an artist and I tried my best drawing this diagram, so if you cannot see a laptop in this picture, don’t be mad.

A generic display assembly includes a very few parts and knowing them will help you to understand witch part can cause a problem if you laptop video not working properly.
Video cable. A video signal from the motherboard goes to the LCD screen through the video cable. The video cable connects to the motherboard (or video card) through the connector 1. The video cable connects to the LCD screen through the connector 2. The video cable (in most cases) is also responsible for supplying a necessary voltage for the FL inverter board. The video cable connects to the FL inverter board at the point 3.
FL inverter board. This board is responsible for converting low voltage DC power (point 3) to high voltage AC (point 4), necessary to light up the backlight bulb. If the FL inverter board is bad, the LCD screen (backlight bulb) will not light up when you turn on the laptop, but you still should be able to see a very dim image on the screen.
CCFL (backlight bulb). When the backlight bulb lights up, you can see an images on the LCD screen. In most cases the backlight bulb is a part of the LCD screen and if it’s bad, the entire screen has to be replaced. By the way, some specialized repair shops can replace the backlight bulb itself.
Lid close switch. The lid close switch is a small button that locates close to the display hinges. On some newer models there is no button, because the switch is magnetic. You can set up your laptop to go to a hibernation mode or to a standby mode when the LCD is closed. It’s done through power management software. These modes are triggered when the display is closed and the lid close switch is pressed down. If the LCD screen on your laptop will not light up when you open the display assembly, check the lid close switch is stuck inside (it might happen because the switch is dirty).
Related articles:
Fixing notebook video problems.
Disassemble LCD screen with water damage.
Screen inverter replacement.
Laptop has bad video on the screen.

Laptop turns on for a moment and shuts down

Today I was able to fix a “dead” notebook simply by reseating connectors. The customer brought in Compaq nx5000 notebook with the following complaint:
“Laptop shuts down on power up. When the power button is pushed, the laptop flashes green lights for several seconds and then powers down. Unit will not stay on with battery or when plugged in”.
I plugged the AC adapter and tried to turn on the laptop. After I pushed on the power button, fans started spinning and were active for a few seconds and laptop just turned itself off. The video never came on. I tried to power it on for a few times with the same result.
Here is how I fixed it.
First of all I tried simple stuff: remove the battery and start the laptop with AC adapter plugged in, reseat and swap the memory module, remove the hard drive, the DVD drive, the wireless card. Nothing helped to start the laptop normally. After that I went a little bit further. I opened up the laptop case, removed the LCD screen assembly and reseated the video card and… Surprise, surprise, the laptop started fine with an external monitor attached. Just in case I restarted it 3-4 times and each time I got video on the screen. After I assembled everything back, one more surprise was waiting for me. The laptop failed to boot again with the same symptoms. So, the only part that I added before it failed was the LCD screen assembly. I unplugged the video cable from the system board and the laptop started fine again with the external monitor. Now I know that the problem is somewhere inside the display assembly (of course, if the video connector on the system board is fine). The next logical step would be opening up the LCD display assembly and check if all connectors are seated properly. Bingo!!! I wasn’t very surprised, but I was very happy. The video cable was half-way out from the connector on the back of the LCD screen. The laptop started perfectly fine as soon as I plugged the video cable back in place. Fixed!
That was my first experience when improperly plugged video cable prevented entire system from booting.
Read more:
How to troubleshoot and fix laptop video problems
Laptop has bad video on the LCD screen. What is wrong?