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.
December 23rd, 2006 at 5:16 pm
[...] I think you might have a failed screen inverter (FL inverter); this problem is very common with laptops. The inverter board acts as a power supply for the LCD screen backlight bulb, it converts low voltage DC power into high voltage AC. On most laptops the inverter board is located inside the display assembly below the LCD screen and you can get access to it if you remove the screen bezel (LCD mask). [...]
December 20th, 2006 at 10:36 am
I have a 4 year old Sony Vaio screen was dim now only lights for a second when I open or manually use the close switch. Do you sell bulbs? Mike
December 18th, 2006 at 8:42 pm
Ryan,
It’s rear but it’s possible. I’ve seen that before 2 or 3 times. It’s possible that the video harness itself is fine, but the motherboard has a faulty connector the harness plugs into. I would probably go with replacing the video harness next. It gives you 50% chance and it’s much cheaper then replacing the motherboard.
It means that data signal is coming from the motherboard to the LCD screen , but there is no power coming to the inverter board and as a result the backlight bulb will not light up. I’m not really familiar with Compaq laptops and not sure 100% if the video harness caries both the data signal for the LCD and power for the inverter, most likely it does. If that’s the same harness, I would probably try replacing it. Sorry man, cannot give you better advice.
December 15th, 2006 at 12:25 pm
Regarding my post below, I should also add that, when i shine an independent light source into the lcd with the laptop on, it shows fine, so I’ve rule out the LCD as a cause also.
-Ryan
December 15th, 2006 at 11:49 am
Hello, I have a Compaq Presario R3000, and about a month ago, the screen went dim and then ultimately out. I’ve troubleshooted it first by replacing the backlight - no luck, then the inverter - no luck. When hooked up to an external monitor - it’s fine. That only leaves the harness that connects the inverter to the main board, right? Or could the main board sitll be the culprit even though it functions fine with an external monitor?
Thanks in advance,
Ryan
December 10th, 2006 at 9:52 pm
hi thanks for the information… Now I’m i had a pob with the laptop is it might the power prob with the screen… i gonna try.. and let know the stiuation….
thanks
December 7th, 2006 at 2:16 am
I m having a problem with my lcd it boots fine but here is a dark screen on my ibm p3 it works fine with an external monitor but it can not play the vedio files (songs) while i plug into the external monitor .Here is a white line also on the laptop screen in the left side of it.I can feel a dim light in it but no any display what kind of problem is it can i sort it out my self,plz reply immiediate.
thank u
sumit solomon
December 5th, 2006 at 4:38 am
Help! The bottom 2-3 inches of the screen on my Dell Inspiron 6000 laptop changes to grey with a bunch of lines in it. When it’s like this, nothing can be seen and the cursor does not work in this. I press on the left side of the screen in this area, functionality pretty much returns; however, the moment I take my thumb off, the image starts to fade and then it turns grey again with no functionality. Thank you!
December 3rd, 2006 at 1:35 am
Brad,
What’s wrong with your Sony laptop? Are you sure that you have a bad backlight and not a faulty inverter board? The backlight bulb is located inside the LCD screen. I know that it’s possible to replace the bulb (never done it myself) but it takes a lot of time. First you have to remove the screen and then disassemble the screen.
I work mostly with Toshiba laptops and created a few disassembly guides for Toshibas. Some of those guides show how to remove the LCD screen. There shouldn’t be much difference between Toshiba and Sony laptops. Read through a few guides and you’ll see how to remove the screen. After that you just have to figure out how take it apart.
December 1st, 2006 at 8:23 am
I have a question how do I get to the back light on a sony vaio fxa-59…. They want $20 for the light vs. $450+ for a completly new monitor or a completly new PC