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 3rd, 2007 at 12:37 am
Hi there..
im suffering the same fate as many here- vertical lines on my laptop (which is not so old). i specifically bought it for the display quality – nec ‘super shine view technology’ crap… and now im stuck with multiple vertical lines on the lcd. the problem is they’re clustered to 3-4 very very close ones.. like one thick line, and they disappear if i put ‘pressure’ on the lcd at some angles. please tell me this could still be a bad ribbon cable. to be very honest, it was just one to begin with – but seeing that putting downward pressure made it go away, i ‘jerked’ my screen somewhat hard 2-3 times.. and now im stuck with this thick one.. dnt tell me how stupid that was, ‘cos i already knw.
also, would u be able to help me with the service manual for disassembly , it’s an nec versa m540 (i knw its sold as packard bell in europe).
February 25th, 2007 at 10:56 pm
I want to know is the Fl Inverter inside the LCD screen. I have a Dell Latitude Cpx.
February 25th, 2007 at 2:22 am
Apoorv,
Probably it’s just a bad LCD inverter. Try replacing the inverter board.
February 24th, 2007 at 1:00 pm
I have a Dell Inspiron 6000 with a WSXGA screen.
Since 2 weeks I’ve been having a problem where the backlight intermittently doesn’t come on when I boot up my laptop.
Sometimes after toggling through the CRT/LCD switch, the backlight will turn on again.
Any suggestions?
February 24th, 2007 at 11:34 am
nevermind. i checked the part number on the inverter i got in the mail and it’s not the one i need. i contacted the guy and should hopefully be able to get the part soon.
February 23rd, 2007 at 2:40 pm
I have a Systemax laptop (yeah I know) and the screen went dark a while ago. I can see the image faintly and it does work with an external monitor. I looked online for a replacement inverter but I couldn’t find one. I eventually found one that is close to the same (website says it can act as a replacement for mine). I bought it and got it today. After plugging it in, the screen sitll doesn’t work. It stays dark the entire boot up/etc process. Is it the bulb? I don’t mind trying to open the lcd… I just want to sorta be sure about it before I do.
February 11th, 2007 at 8:19 pm
No I could see it on the external monitor. They say it’s the FL inverter but I just don’t know where to find that in the dell latitude Cpx
February 11th, 2007 at 12:48 pm
Marilyn,
Test the laptop with an external monitor. If you get the same problem on the external video, probably you have a bad video card.
February 10th, 2007 at 7:41 am
Great site and drawing of the laptop!
I have Dell inspiron 8100 that has the equivalent of snow…colored lines with mixed, squiggling color, but still able to read display. The problem comes and goes, unrelated to how long laptop is on.
Can you help? Thanks!
February 10th, 2007 at 12:03 am
how do I reset nvram on a toshiba satellite 1955 with no video post