Screen backlight lamp
A backlight lamp (also know as backlight bulb, screen backlight, CCFL tube or bulb) is the main and only source of light in a laptop LCD screen. A typical laptop LCD screen has only one backlight lamp installed. The backlight lamp mounts inside the laptop screen in the lower part of the screen as it outlined on the picture above.
A pair of cables with one connector coming from the screen plugs into the screen inverter board.
The backlight lamp receives high voltage AC power from the screen inverter board which receives low voltage DC power from the motherboard via the LCD screen cable as it shown on the picture below.
On the next picture you see a typical backlight lamp removed from a typical laptop LCD screen. There are two cables soldered to both sides of the backlight lamp attached to one connector.
BACKLIGHT LAMP REPLACEMENT
It is possible to replace a failed backlight lamp with a new one but it’s not easy because the backlight lamp is buried deep inside the LCD screen and it’s very easy to damage the screen during the disassembly process. This repair should be performed only by an experienced technician. You can find some home made backlight replacement instructions if you do this Google search. For inexperienced people it would be much easier to replace the whole LCD screen.
BACKLIGHT LAMP FAILURE SYMPTOMS
1. The laptop screen lights up only for a short period of time or will not light up at all. The image on the screen is so dim that you can barely see it. At the same time, an external monitor attached to the laptop works fine.
2. When you turn on the laptop, the screen works fine for a while, then start flickering and the light turns off. Again, there is a very faint image on the laptop screen and external video output works fine.
3. The screen works but the image has a reddish/pink tone. External video output works fine.
The backlight lamp failure symptoms are very similar to the inverter board failure symptoms. If you have to guess which one is causing the problem, try replacing the inverter board first.
July 8th, 2010 at 10:38 pm
Alex,
It sounds like you have two different problems in one laptop.
Do you still have a dim image on the laptop screen? Did you try reconnecting the video cable connector on the back of the screen?
July 7th, 2010 at 7:02 am
Hello,
I have a problem and I can’t figure out what the problem is. It started with a dim display. I tried another inverter but it didn’t solve it. I could use the laptop with an external monitor but now that doesn’t work anymore. The ext. monitor won’t start up(tried it with several ones) so I’m afraid my video card might be broken as well now. Windows works, I can hear the login sounds. Could you please give me an advice? Any clue on what the problem(s) is/are?
May 15th, 2010 at 5:48 am
Hello, I have a Compaq Presario V2000 laptop. My LCD screen started getting a red tint all over the screen so I replaced the LCD cable in it. Though, after that, the whole screen became dim so I couldn’t see it even when it was still showing.
So, I looked around and bought a replacement inverter for my laptop but got the same result. Then I bought a brand new LCD monitor and surprisingly didn’t work either. I tested the new LCD on my dad’s HP Pavilion DV1000 and the backlight turned on from pressing the lid close switch. I also tested my LCD cable and the inverter and it shows that it works on the other laptop as well.
Could it be my lid close switch that is causing the problem? I can still press it to make it go to standby but the backlight doesn’t flash on. Thanks in advance!
May 9th, 2010 at 7:08 am
i have problem from dell vostro 1310 there is a screen problem its showing white screen. and not showing windows? i had connect external monitor its working. plz help me
May 8th, 2010 at 4:46 pm
I have a sony VAIO laptop which lately showed signs of a screen problem. During a cold boot everything works fine, but when i start to reboot it, the screen shows only a white blank screen. I can hear Windows starting normally but you see nothing on the screen (only white). This symptom has been on for a while that even a cold start would show also a white screen. I tried connecting an external monitor and everything worked fine. I have replaced the lcd screen with a new one but the problem still persist from time to time. Could this problem be related to a bad inverter or backlight? Are there other components that would affect this problem like power supply, battery transfer switches etc? Appreciate the help, thanks.
April 12th, 2010 at 8:20 am
Mamta,
Can you test your laptop with an external monitor? Can you get video on the external monitor?