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.
Looking for a new screen, video cable or inverter board? Find it here.
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.
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October 23rd, 2006 at 10:35 am
[...] If you take a look at the generic notebook display assembly diagram, you’ll see that there are four parts that can cause the backlight failure: lid close switch, video cable, FL inverter board, CCFL (backlight bulb) itself. Let’s go through them one by one. [...]
October 21st, 2006 at 5:16 pm
I have a toshiba satalite p35-605 17 in laptop and i bought a cable to connect to the tv. I have tried to get it to display on the tv for hours, but its not working. I used the fn f5 key and altered settings in the properties but nothing seems to work. the tv screen will flicker, but doesnt do anything else. if anyone knows what might be the problem let me know. I have tested the cord with other computers and it works fine. thanks
jon
October 18th, 2006 at 7:42 pm
Rodrigo,
It’s not your fault that you have these lines and unfortunately you cannot be safe from this problem in the future, it might happen again on any other screen. I’m almost positive that’s a bad screen, I cannot be sure 100% without looking at the screen.
October 16th, 2006 at 9:07 pm
Thanks cj… It looks like that… But now I have way more lines than that! hehehehe…
So my only hope is to replace my entire LCD? Do you know what causes this problem? I don’t want that to happen again!
October 16th, 2006 at 5:17 pm
Rodrigo,
Check out my post related to a bad laptop video. Does your screen look like example 2 in the post? If yes, then most likely it’s the screen problem.
October 15th, 2006 at 10:30 pm
First of all, thanks for the great site!
I had the same problem as ngbede. I have a Toshiba P35 with a 17” widescreen LCD. One day, a vertical line appeared at my LCD and since then they increase day by day… They start at one color and progress to white… One component of the RGB is always turned on for the entire line, but others components continue to work for some time and then they all turn on.
I read something on the web about a “LCD driver” (not the software driver) that may be damaged if overheated. I had problems with overheat caused by a dirty heat sink.
What can I do to fix this? My local tech tried to play with the cables with no sucess.
September 17th, 2006 at 6:09 pm
Sophie,
I guess that a bad LCD screen. Take a look at the third picture on this post, your line looks the same, right? The screen should be replaced and it’s necessary to take the laptop apart. So, I think there is nothing that you can do yourself. Screens are expensive, and it could be more cost effective to buy a new laptop then to replace the screen.
September 16th, 2006 at 1:47 pm
Please help me im hopeless with computers!!!
I have a dell inspiron 6000. I turned the laptop on this morning and straight away there was a single vertical yellow line about 3 pixels thick right down the middle of the screen. This line is present through all the programs and ive tried rebooting the computer.
I have no experience to start taking the computer apart: is there anything i could try before taking the computer in to see a tecnician.
Please help
Sophie x
September 9th, 2006 at 8:32 pm
ok i have a dell inspiron1150 i read the artical of fixing the dim screen ok when i first turn the computer on i see the dell name for a sec then its all dim i looked for swicth no luck in fiding one but i see talked about magnet which i did find whats the magnet pull a switch from insode the computer or is there something else wrong with it . it did it before but i left it alone foe few days then it worked but the time its staying dim .need some help dont really want to get a new one
September 8th, 2006 at 1:34 pm
I’ll try anything!
I think I will look for one and see if a friend can fix it for me as he is good with computers, not sure about laptops, but they’re sameish.
Cheers for your help