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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July 30th, 2009 at 7:36 am
hi my Acer aspire 9302 screen is totally blank/black.If i press the power on button and press f2, bios displays correctly but when i try to boot into windows, i get NTDRL(or something like that)FAILED and then the screen goes black/blank again.fans are working,HDD working(i think), blue tooth working.Have not tried it successfully with an external monitor yet. Can someone please help me out here as the laptop is brand new and i went through a lot to get it. Thanks
July 29th, 2009 at 8:15 am
my IBM T21 is not booting. I checked the battery ,CMOS cell,replaced RAM.In DC mode or in adapter mode it does not show any indication but grenn led glows (right top first)when charger is connected . when power switch is hit the system indicator just flash and goes off no screen no beeps no other indications
what may be the reason
July 16th, 2009 at 5:41 am
Guys I have problem with my HP Pavilion dv9000, when i turn on the power button it won’t function, i put the power cable to charge the battery and when i push the power button there is no function at all, the power led is off, only the charging led is on….. was it the system board is damaged? PLS HELP ME GUYS…TIA..
July 12th, 2009 at 11:27 am
I am having a black LCD problem and tried the ON OFF exercise many times with no sucess. Do you repair laptops?
I have an Alienware Area 51 M5550 that just started to have this video display issue. When I turn the notebook on the screen is totally black as if there is no connection between the “box” and the lid or video display. Even though the screen was black the computer was booted and running fine as I got to all my “shared” files via my wireless network. I turned the notebook on and off a number of times with no luck.
Then this morning I turned it on and I had full video. Backed up all the files and turned the machine off. When I tried to turn it on a few minutes later – black screen.
When I tried your Fn + F4 trick I got most of the video screen back ie: I can see and use about 75% of the screen. No what? And where do I get this fixed?
July 10th, 2009 at 7:13 am
i have a power failure on my laptop pls how can i repair it pls send the answer to my mail pls i need ur assistance
July 1st, 2009 at 6:13 am
As I read some of these postings I see a lot of similar problems to mine. That is, the backlight does not come on and the video is working. At first I thought it was the close lid switch, but after disassembling the monitor on the Toshiba P205 I noticed that it uses a magnet to activate a reed switch. Also, when I close the lid (or run a magnet across the palm rest) the laptop goes to sleep, so I am to assume that the switch is working. -I have also connected an external monitor which does work. I don’t know if it is the backlight, inverter, or the power cable for the inverter (same as video cable). When I get home tonight I will run some tests and post back with the results. The symptoms to the problem are:
-the monitor goes blank almost immediately after turning the laptop on
-If the lid is opened and closed repeatedly (litterally) the backlight comes on for up to a few minutes then goes off
-the monitor does not respond to blunt force or shaking of the monitor
-at times when the backlight is on, it seems that only half of it is lit.
June 27th, 2009 at 10:41 pm
Nathaniel,
Take a closer look on the laptop LCD screen? Can you see any image at all? Maybe the image is there but it’s very dark?
Have you tried switching video from the external mode to internal using Fn and F4 keys? Press down the Fn key and at the same time press once on F4.
If there is no image on the laptop screen at all and Fn+F4 doesn’t help, there could be a problem with the video cable.
June 24th, 2009 at 4:09 pm
I have a v2000 persario I have replaced the LCD and the Motherboard. I can hook up an external monitor and see it booting but still i cannot get anything to come up on the LCD. Talked to tech support and still I am not getting anywhere!! Is there any other parts that can be replaced..
June 17th, 2009 at 12:33 pm
hi there i have a fujitsu siemens amilo pro v2030, the screen is not functioning correctly as is very dim, i replaced the invertor but symptons still persist the invertor was purchased from ebay but sellers assured it was checked and 100% working before dispatch can i assume that its the backlight bulb that needs to be replaced or could it be the ribbon, thanks in advance
April 4th, 2009 at 6:34 pm
Jofel,
I don’t think it’s possible. At least I have seen any tutorial on converting a laptop LCD screen into a desktop LCD monitor.