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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March 17th, 2007 at 8:54 am
Hello i am having m,ajor problems with turning on my computer.it satrted when i insatlled a program call system mechanics 7.0 .It was to advanced and i did not know how to use it.Any it cleaned away my web roser and i could not get on the internet.So i went back and reinstalled everything that was removed from my computer.Shortly after that my lap top made ths crazy beeping noise and it would not stop.Orange light came on too.i shut off manually .Then i went to turn on again and it would start for about 3 sec.then shut off.know i can not turn it on at all.I bought this from a friend and there is no warrenty i live in the deep north.And would cost alot to send away.Is this a mojor problem or can i fix this my self .Is my computer completely destroyed by a virus that i re installed ?please for the love of god get back to me please.
March 12th, 2007 at 10:53 am
CJ,
Yeah, I’ve used it with an external monitor so I know the video card (etc) still works. I can also see a faint image on the screen (which is how I know it’s not the lcd screen itself). I’m probably going to take the screen apart later today to check the bulb size and order a new one. I have a friend that has a soldering gun so I should be able to mount it once I get it. If you have any further ideas on what it could be, I would greatly appreciate the info. Thanks.
March 12th, 2007 at 8:58 am
i have a notebook 2800t which only displays the backlight and has no image showing. i have tried connecting it to a external monitor and it shows up to the xp screen fine then it turns the screen off but continues to boot on the laptop… i have also tried booting it in safemode and vga mode and the external works fine but as soon as you try to put the resolution up in vga mode it turns off. id love any help on trying to get the laptop screen or at least the external working (as i really cant afford a new screen) any help would be very appreciated thanks!
March 10th, 2007 at 5:32 pm
Clinton,
Did you test the laptop with an external monitor, can you get any external video? Can you see a faint image on the LCD screen? If you have a bad CCFL tube the laptop still should work with an external screen and you should make out a faint image on the laptop LCD.
March 10th, 2007 at 5:09 pm
mangesh vasiya,
check the memory module, try reseating it. If it will not help, swap it with a known good memory stick and test again.
March 8th, 2007 at 9:09 pm
Hey. I know problems are posted all the time, but I am still in need of help. Earlier I thought that the inverter I ordered was the wrong one, so I ordered a different one. The screen still doesn’t light up though. The only thing I remember from the night it stopped working was a distinct burning smell from the back of the laptop (near the fan). Do you think this could be the CCFL tube or something else? I’ll probably end up getting it repaired unless it’s something sorta easy to fix. Thanks for any help.
March 7th, 2007 at 10:22 am
i ahve mercury green320 laptop it have problem no dispaly.no beeb,power is on,but no beeb comes & no desplay.
March 6th, 2007 at 1:55 pm
Hi there,
I want to buy/assemble a LCD desktop monitor like the one I have in my notebook (15.4″, WSXGA+).
Can you possibly give me any further reference, please?
Thank you so much.
March 4th, 2007 at 2:14 pm
lostnrestless,
Yes. On some models the display will go white when you unplug the data cable from the screen. The lines disappear because there is no signal coming to the LCD.
From my experience, when you have a bad video cable it will affect image on the entire screen. You can get no video at all, corrupted video, bad colors, etc… but across the entire screen.
If you have a few vertical lines running across the screen, as it shown in the example 2 in this post, then most likely you have a problem with the screen itself.
March 4th, 2007 at 1:40 am
thanks for ur reply…can i bother u one more time, this time with more specific details:
with help frm ur posts i managed to take out my lcd screen.. to reach the ribbon cable at the back (thanks for improving my knowledge of laptop hardware by leaps n bounds btw!). i was fiddling around with the ribbon cable when i noticed this – if i take out the ribbon cable and power up the display is pure white (ccfl bulb) but WITHOUT those annoying lines. is that to be expected? to rephrase, since those lines come up only when the ribbon cable is plugged, im wondering if it could ’still’ be the ribbon cable??
also no angles/pressure does anything anymore after i’ve tinkered with the ribbon cable on the backside. the lines are now like a shaded area about 7 pixels wide.
thanks again mate.