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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October 1st, 2009 at 10:38 pm
I wish I could find the toshiba software applet for the P25 S607 that controlled performance
I’d like to set this dust magnet to long batter, low CPU power as it is now a usenet scoop.. and chewing through electricity
it is a great space heater now
September 26th, 2009 at 1:45 pm
sarah,
Can you test the AC power adapter, just to make sure the laptop is still getting power from the wall?
Most components inside the laptop are mounted on the motherboard. From your description is sounds like one of the components have failed. I cannot tell if this component can be replaced or you have to replace the whole motherboard without removing the motherboard and taking a closer look. It’s necessary to remove the motherboard for further investigation.
Most likely yes. You’ll have to buy an external USB enclosure for notebook hard drives. After that you mount your hard drive inside the enclosure and connect it to another working computer. The hard drive will pop up in My Computer. You should be able to access the hard drive and back up your data.
September 26th, 2009 at 1:09 pm
Hi,
My IBM R50 laptop was on for hardly 15 minutes and connected to a power supply when I heard a short frizzling sound and smelt burning. In a matter of seconds the machine went dead. I unplugged it from the power supply and tried restarting but nothing happened.
Has it anything to do with the power supply inside the laptop? Can it be changed? Or could it be the motherboard?
Do you think even if the laptop does not ‘revive’ is there a way of getting my stuff from the hard disk?
Thanks for letting me know.
September 22nd, 2009 at 11:47 am
motoplux,
I cannot tell, could be either one. They both have very similar failure symptoms. I would definitely try replacing the inverter board first.
September 22nd, 2009 at 11:30 am
Hi there.
I have a problem with my Toshiba M50 LCD. It happens that when I increase the brightness of the screen after few seconds the image becames very dim (the lcd seems to be black but looking well the image is very very dim). Closing and reopening the lcd, in order to switch the lid close switch, the screen lights up again, but after few seconds same problem. Instead, getting the brightness to the minimum, and lighting up the screen, the LCD dosn’t switch off anymore. Do you thing it is an inverter problem or a backlight lamp problem?
Thanks in advance
August 28th, 2009 at 10:00 pm
amber,
Take a look at the example 2 in this post. Does it look like your problem? I think so.
Sounds like you have a problem with the LCD screen. You’ll have to replace the screen or use it as is.
August 28th, 2009 at 2:43 pm
Hello,
I own a 4 year-old Laptop and some weeks ago 3 coloured lines apeared on the screen (pink and yellow), they are very thin but even though they disturb me when I watch movies.
I am really not a computer expert so, could somebody please tell me if it is an unrepairable damage of the screen or if I can somehow fix it?
Thank you very much
August 17th, 2009 at 8:25 am
Hi,
A friend of mine asked me to replace their notebook screen as they got liquid into it.
I replaced it and the screen would not light up so I thought the backlight must have been damaged in transit. I was sent a second screen and have just fitted it but the same issue exists.
You can just about see the image but the backlight is not coming on. I also connected an external monitor via the VGA port which works fine so what else could be causing the issue?
Thanks
Paul.
August 3rd, 2009 at 3:29 am
i have a toshiba lao top that was not coming on, so i open it removed the video and it powered. i tested the voltage input and notice it had short circuitwish the video memory. PLEASE I AM LOOKING FOR THE VIDEO CARD
July 30th, 2009 at 8:09 am
Jason,
Sounds like a software related problem. NTLDR is on of the main boot files for Windows. If it’s missing or corrupted, Windows will not start.
First of all, try fixing the problem by running the repair process from the installation disc. Boot your laptop from the recovery/installation CD/DVD and select the repair option.
If it doesn’t work, try reinstalling the operating system from scratch. This will erase the hard drive so all personal files will be gone. Again, run the recovery disc and instead of repair choose another option – reinstall OS.