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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February 4th, 2009 at 2:45 pm
micheal,
If it fails again even with a clean lid close switch, most likely you’ll have to replace the inverter board.
February 4th, 2009 at 2:38 pm
thanks so much, mu laptop monitor would flash on setting changes, I used a flashlight to see while I dragged windows to to my ext display. Almost felt like I had to change my lamp or converter, then I saw your “Dirty cover switch” possibility. I played with it, pushing it in and out rapidly, monitor flashing every push, the viola! it stayed on,. thanks dude,. you saved me alot of frustration
January 28th, 2009 at 5:38 pm
my laptop could only on for as much as used my hand to clip it to the ground.what could be the problem
November 23rd, 2008 at 1:28 pm
from jack w on 10-Nov:
“I have an hp dv2210 and the screen flickers off and on and dim and on. ….”
Update: 23-Nov
I ordered a inverter board for my dv2000 for $25 that incl shipping. Replaced the board and all is fixed. I only had to remove the display bezel. The display plug broke apart on disconnect but I was able to piece connections back together when replacing board. works !
jack w
November 10th, 2008 at 2:02 pm
I have an hp dv2210 and the screen flickers off and on and dim and on. Sometimes it will really flicker for a few minutes then go dark where I can see a faint image of the display.
Here is what I have observed trying to troubleshoot without disassmbly:
1) When on AC the problem gets a bit worse than on battery
2) If I restart repeatedly it will eventually work normally, usually 3-4 times on battery.
3) Problem is getting more frequent as I think something is starting to fail.
4) External monitor works normal.
I am thinking its an inverter board going out???
jack
November 10th, 2008 at 4:46 am
Hi, thanks again for such an informative site!
If you have a moment for advice, I would greatly appreaciate it. My Acer aspire 5100 has had intermittent days when it starts up but with no display at all. Now its looking like its gone permanently. I tested it on an external monitor and all is fine there. System is working fine.
Had it into acer to repair the issue under warranty 6 mnths back, and they replaced the mainboard, but didnt solve the problem.
Im suspecting the inverter, and am happy to replace it but Im confused since I frequently hear that without the inverter/backlight, I should still be able to see a very faint image on the screen. I cannot. When Im in the system on an external monitor, it doesnt show the ‘default monitor’ as being active, as if its disconnected. Should I be looking at the display cable into the board (twisting damage etc) and if so, how do I get in there (above or below)?
Also, does the intermittent nature of the problem sound like the inverter or cabling? Used to be most common after travel (especially by air)
Many thanks in advance!
October 31st, 2008 at 7:55 pm
try jiggling the handle
October 6th, 2008 at 7:13 am
Hi I have a parkard bell laptop and I am just trying to figure out what is wrong with it, it’s two years old and recently has not been charging proberly, it then went through a phase of the screen going blank but still being on, now when i plug the power adapter into the laptop the green light on the lead flashes on and off and it makes a clicking noise and it smells like burining and doesn’t charge. Firstly I thought this was one problem but now i, begining to think after reading a few posts that it is several, roughly how much would these problems cost to fix?, I don’t want to be over charged
Thanks
October 3rd, 2008 at 8:31 am
I have a toshiba p25-s607, the unit is approximately 5 years old no warranty. When I boot up I get roughly 10 green/black rows across the entire screen and nothing else. Is there a way to either replace the video card and/or the motherboard on these units?
September 20th, 2008 at 9:53 am
Bruce,
Not really. If you have a problem with backlight, the only 100% guarantied way to find the culprit is testing the laptop with known good parts.
I usually use a spare backlight lamp witch I removed from an old cracked LCD. When I have to troubleshoot a laptop with backlight problem, I unplug the LCD screen (backlight cable) from the inverter board and plug in my test backlight lamp.
1. If my test backlight lamp lights up, the backlight lamp inside the LCD screen is bad and has to be replaced.
2. If my test backlight lamp doesn’t light up, most likely it’s bad inverter.
I’ve been using my test backlight lamp with many different laptops and this method works fine.