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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November 16th, 2009 at 11:59 am
Matt,
It’s possible that the backlight lamp is not seated correctly inside the LCD screen.
Also, try reinstalling the video driver. Read this article: http://www.asklaptopfreak.com/.....placement/
November 16th, 2009 at 3:13 am
We managed to replace the backlight in my Dell inspiron 6000 but the screen does not light up evenly. It is bright at the bottom and darker at the top. Also the brightness adjustment does not work.
I would greatly appreciate any comments from any one who has had the same problem. By the way I also replaced the inverter at the same time so i know it is working.
Many thanks
November 6th, 2009 at 10:30 am
adl,
Here’s something to try.
Turn off the laptop. Unplug the power adapter. Remove the battery. Wait for a couple of minutes. Plug the power adapter and try turning it on again.
November 6th, 2009 at 12:11 am
hi
i need help
i have sony voia laptop last night was workin ok but when i turn it on this morning the light is on and i can hear the fan but no screen shown how can i fix this.
thank you
October 18th, 2009 at 9:42 am
cj2600, thank you. I have been thinking it is the LCD, too. But like you say It would be wise to check the cable connections to the video card/motherboard. I guess it will just take diving into the lower half of the laptop to learn how to access those connections. I assume by removing the keyboard.
I may have to return for more questions later. If any new advise and wisdom is out there for me, please don’t hesitate. I am not a bad do it my self guy, but this laptop/electronics thing is not my comfort area at all. But I think I will be getting better acquainted real soon.
Than you again,
Keven.
October 17th, 2009 at 10:35 pm
Keven,
Most likely you damaged the LCD screen and it has to be replaced.
There is a very very slight chance that this is connection related problem. Maybe the video cable got disconnected from the video card somehow and not seated properly. Before replacing the LCD screen take a look at the video cable. Make sure it’s connected properly. Try reconnecting the cable. If no help, you’ll have to replace the LCD screen.
LOL. I think he was joking.
Or maybe he wasn’t a technician at all.
Your problem is not related to the inverter board, that’s for sure. Let me explain myself.
The inverter board is a power supply for the backlight lamp inside the LCD screen. All it does is converting low voltage DC power into high voltage AC. If you can see the top 1/3 of the scree and it’s bright, it means the backlight lamp and inverter board work properly. When inverter fails, the ENTIRE screen is completely dark.
I think you have damaged the LCD screen.
October 17th, 2009 at 10:03 pm
I have a Gateway MX6453 notebook. It slipped off the table and even though my leg broke its fall it hit the floor with a direct hit on the back corner of the laptop. Now the screen is only working on the top 1/3. It looks great up there. But the bottom two thirds is completely gray. I light gray, and has no image showing through at all.
This happened about a year ago. I can hook up to an external monitor and with good results, but it takes a lot of guessing to find the right place to click on the laptop monitor to open the right controls for setting the laptop to work on the ext. monitor.
But that is not the question I have. I talked to a gateway service tech on the phone. Even though my warranty is long over he was nice enough to tell me he thought my problem is for sure the back light inverter. He told me it would cost 150-200 to fix. I just today looked and found ebay has them for under $10.00. I even opened the screen and verified the cables are connected on both ends and also the p/n. I am not sure how to check the cable as it is connected to the mother board.
Anyway, what do you think my problem is?
Please email your reply if possible. But I am going to book mark this site too.
Than you, Keven
October 8th, 2009 at 5:09 am
I have a Toshiba Satelite that seem to work perfectly until the screen is moved on its hinges. Depending on how far back it is moved the screen will either go mostly dark with a few lines showing (no image) or it will still have all colors Image can mot be seen). In only 1 out of 100 times can you move the screen back to get the correct image. The solution to getting your screen back is make sure it is displaying in color mode (Not Dark)
1. Put it to sleep and then wake it up (100% recovery)
2. Alt Ctrl Delete (50-75% recovery)
3. Alt Ctrl Delete then if still unreadable arrow key down once and enter (Switch User) (90-95% recovery)
Notes
a. This only happens when you move the screen.
b. It works perfectly with ext monitor even when the screen is dark.
c. I have taken the screen cover off and determined the issue is under the left side hinge where the cable from the screen (not the cable to the invertor) goes into the motherboard.
My questions are:
1. If it is a short then why does it come back to life after the above procedures. Wouldn’t it stay off until the short was resolved?
2. Can I go into the connection on the MB or is this better left to laptop techs?
Thanks for your help and thanks for the service you provide here.