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 7th, 2010 at 9:06 pm
Hi I’ve got a Compaq V2000 working fine till I got back yesterday after leaving it on downloading stuff. I now have bottom 2/3 of the screen having horizontal bands across that looks like double images. Tried to reseat the video connectors don’t work, hooked to an external monitor and it works fine. Could it be the lcd that need to be replaced or should I try a new cable?
Thanks
February 24th, 2010 at 1:25 am
thank you sir, I learn more from you.
February 22nd, 2010 at 2:22 am
dear sir
i hv reformat and reinslatted win xp sp1 to my another toshiba satellite l300 but the camera cnf7051 cant be installed and the pop up ‘webcam drive open fail. restart camera or computer’ keep pop up. i ve done it so many times but stll cant install the driver i ve downloaded the driver from toshiba site but seems doesnt work up. help me
thank you
ps your site very helpfull for those need an advised
February 22nd, 2010 at 2:12 am
dear sir
i hv acer travelmate 6292 my screen appeared to be very dark but still can see an image when look closer to it and when connected to external monitor, what should be repaired the lcd, backlight, inverter or the video cable?.
need your help and advised.
thank you in advanced
February 17th, 2010 at 10:45 am
Did you ever solve this problem?
I have a similar problem to #126-George. I have a dell Inspiron. Half of the screen went black so for a while we plugged in an ext. monitor and I ordered a new lid for it (It was cheap) installed new lid, it worked great, then plugged it in and went dim (cord was frayed) ordered a new inverter installed it. The screen is dim, will get bright when I run diagnostic test then says error accessing lcd inverter. When I go back to regular mode, screen is again dim. (controls neither brighten nor dim screen)
February 16th, 2010 at 11:49 am
Jc Shaulis,
If you have a question you can post it here. I’ll answer If I know what’s going on.
February 16th, 2010 at 3:06 am
Yo, I tried to email you because of an issue I had on this post, but I can’t really figure out a way to find you. If however you see my email address, can you send me a e-mail? Thank you.
February 7th, 2010 at 1:01 pm
Kris,
If the top 2/3 of the screen still works fine, this is not inverter problem. That’s for sure. Your description sounds more like the LCD screen failure.
I’m pretty sure that you’ll have to replace the LCD screen.
That’s right. The video card works properly.
February 7th, 2010 at 12:58 pm
I am working on this laptop for someone and the LCD seems to be messed up. I am not sure if I need to replace the LCD or the Inverter board. Here is what is going on. The Top 2/3 of the screen is just fine. The bottom 1/3 of the screen is a bunch of vertical lines. When you move the mouse to the bottom of the screen the pointer disappears in the vertical lines. I hooked it up to an external monitor and the screen on the external monitor is just fine so I don’t think it is the video board. I just need to know what to do. Replace the LCD or the inverter board. Any help is appreciated.
January 25th, 2010 at 11:59 am
Hi
I have a problem with a HP ZV5000. I received it with no hard drive and at that point it appeared to boot but there was no LCD or external output (I was told by a friend this was ‘a thing’ with some HP’s). I have now salvaged a HDD from another laptop, and formatted and installed XP, gone to the HP site and downloaded all the relevant drivers I can find. The notebook works fine but the LCD screen is black. There is output to external monitor now though. When I press Fn/F4 (screen toggle) The external goes blank for about half a second then comes back on. Nothing happens with the LCD, So I presume maybe inverter? or back-light?? However, when I boot the laptop using puppylinux it remains black until The X???? (i forget the name) video driver detects the card, and at this point the LCD light ups glowing a lovely white/grey colour (this is done with a CRT plugged in so I can see what is going on). Still no picture though.
I am stumped as to what might be causing it. Is it a driver issue? But then why don’t I get an OS splash? Sorry for prattling on I have looked all over the net for a solution but am failing to find anything similar.
Thanks for reading everyone.
DTB