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.
Laptop parts | Repair Man | 
December 26, 2008 3:15 pm
April 23rd, 2012 at 7:15 am
Hi,
My Toshiba Satellite A200-TR6 Laptop’s LCD screen is very faint however external monitor works fine.
Laptop’s back light bulb sometime works fine for hours but most of the time remains very faint. I already replaced inverter board which didn’t help.
Is it back light bulb working intermittently or the input voltage and or control signal to inverter are intermittent?
How can I verify if input to inverter is not causing problem?
Thanking you in advance…
Arvind
April 11th, 2012 at 11:54 am
My laptop boots up and i see a faint logo and then all goes black. The lights on the inverter seem to be working normally.
I got a new screen but it came with the wrong back light plug (two pin vs. Ribbon). I tried booting up with the new screen without connecting the two pin back light and i get the same result; faint logo and then all goes black
to me it seems the inverter is fine but the back light on the old screen is gone and once i find a replacement screen with a ribbon connector i should work?
Does it seem like the back light or inveter is faulty to you ?
December 12th, 2011 at 5:40 pm
@ kayla younger,
Please test your laptop with an external monitor. Do you see same red fuzziness on the external image or it’s working properly?
Were you able to fix it before by moving the display back and forth?
December 12th, 2011 at 3:45 pm
@ joehe4,
Yes, it’s very likely that your problem related to the backlight lamp failure.
Yes, it’s possible but not easy.
You can look at this example of replacing the CCFL on a laptop screen.
http://www.laptoprepair101.com/laptop/2007/12/09/replace-laptop-backlight-ccfl-lamp/
When CCFL fails, I recommend replacing the entire screen.
November 29th, 2011 at 4:20 pm
i have an hp laptop, everything work completely fine on it and it is not slow at all. my only problem is ever since i first got it aall the darker colors or sometimes just the black color to anything is this bright fuzzy looking red color, it use to fix its self and go back to normal but now it stays that way constantly. i cant look at pictures or watch movies or anything like that because of the color.
November 24th, 2011 at 11:26 am
i have a sony vaio vpc-eb1j1e at start up it goes fine, but after the windows has open my screen starts to flicker and went black. i already check it by replacing the inverter and the thing happen, is this might be the backlight problem, is it possible to change the backlight??…
November 21st, 2011 at 7:34 am
@ ambersky,
Most likely it’s either bad inverter board or failed backlight lamp (inside the screen).
You cannot tell which one is causing the problem without testing the laptop with spare inverter or backlight.
If you have no spare parts, I would try replacing the inverter board first. There is a good chance to fix the problem.
November 19th, 2011 at 11:48 pm
Hey Please help me my laptop works just fine But the screen In dimmed and i can get it any lighter!I can see the screen saver but it is very dark! Im getting worried is this just cuz the back light has blown!??
October 25th, 2011 at 7:08 am
@ Repair Man
Thanks!
October 25th, 2011 at 6:47 am
@ Dawn,
Probably this is video cable related issue.
1. check connection between the video cable and motherboard.
2. check connection on the back of the LCD screen.
3. replace video cable.
October 25th, 2011 at 6:00 am
Hi all,
Hope someone can point me in the right direction (LCD Screen, Crimped Cable, Backlight, Battery?????)
I have a Toshiba L505D-S5992 Satellite laptop. Recently the display began to dim after the laptop screen is lifted to a certain point (i.e. 1/2 way). The symptoms after hitting that 1/2 mark (same every time) are consistent with an Inverter/Backlight failure. I replaced the Inverter and still have the same problem. The LCD is normal (no spots, lines etc… until the LCD screen is lifted to 1/2 way then the screen Darkens to black although you can still feintly see the image if you shine a light or look closely enough. Attaching an external monitor works fine.
Any feedback would be great!
Dawn
August 12th, 2011 at 5:57 am
Will the inverter in a dv2000 work in a dv1000? Thanks!
August 3rd, 2011 at 7:20 pm
I just noticed that the screen brightness of my laptop (hp hdx 16t)has decreased. its not dim as you would see when using the battery but you’ll notice that the white
background of websites (e.g. yahoo, youtube, google) are a bit off-white (dirt white).
i compared my laptop’s display with a Sony vaio laptop (vaio cs23) and i noticed that vaio’s display are brighter even under default settings. i always use my laptop under AC power and with no battery attached. i already updated my bios a long time ago.
I already tried the following:
1. fn + f8,
2. adjusting the brightness under Control panel/personalization/windows color
and appearance
3. uninstalling then reinstalling Nvidia display driver
4. when i adjust the brightness under Nvidia control panel, the screen appears foggy white and its a strain to the eye.
could it be a sign of an aging backlight or inverter problem? it annoys me to see that white colors has now become off-white.
franz
June 18th, 2011 at 10:10 pm
Hi! I recently ordered a replacement laptop backlight for my toshiba a25-s3072 laptop. I ordered the backlight assembly with wires. I tried to fit it back in the lcd screen assembly where the backlight assembly is suppose to go. I feels like it is tight and bulges. I secured it with screws so I can test the backlight and plug it in with the inverter to fire up the laptop. When I turn on the laptop, all I can see is the reflection of the lighted backlight on screen and only is illuminating 1/4 of the screen and is booting up but it is faint. How do I make it illuminate the screen brightly because it only has a faint glow of the backlight on the lcd?
Hope you can help. thanks.
May 18th, 2011 at 5:05 am
I have a Dell Inspiron 1545 at times on start up my screen goes very dim. You can hardly see image. I have replaced inverter board and problem remains. Laptop works fine on external monitor. Have restart computer several time before the screen stays on. Do you think the backlight is bad and need replacing. Plz advise
March 2nd, 2011 at 8:15 pm
panchito,
What do you mean the BIOS setup looks the same? Does the BIOS screen normal, full screen?
What if you boot the laptop in safe mode? Is it working properly in safe mode?
If you can see full screen in safe mode but no in normal mode, try reinstalling the display driver.
February 24th, 2011 at 5:31 pm
hello i replace the screen hp pavilinoDV4-1548DX 14.1
but i can only see part of the window, the right side its dark,
appears the screen resolution its bad, but in the bios setup, looks the same
February 11th, 2011 at 4:56 pm
mani,
Can you see any image on the laptop screen? Looks very closely. Maybe the image is there but it’s very dark?
If that’s the case, try replacing the inverter board.
February 10th, 2011 at 6:01 am
Hi I have H.P Dv 2000 laptop with me, ther is a problem witch i am not able to view my scren proprely, but ther is display and it is working with external monitor, give me solution………
February 2nd, 2011 at 4:10 pm
Greetings,
Lately I have been facing problems with my pavilion dv9700. The LCD brightness keeps flickering. Since it is a dual lamp display, the left side seems to be dimmer than the right, when both should b equal.
What do you suggest I do? I have logged in to Linux, and the problem persists so I am pretty sure there is a hardware problem. Possibly the inverter or lamp? Please advise.
LH
January 7th, 2011 at 9:19 pm
prabhat,
It’s hard to tell what is failing. Could be:
1. Bad connection between the LCD cable and motherboard. Try reconnecting the cable.
2. Bad LCD cable. Try replacing the cable.
3. Bad LCD screen.
4. Not likely, but possible – bad video connector on the motherboard.
It’s hard to troubleshoot this problem without spare parts.
January 7th, 2011 at 11:23 am
Hi
i have lenovo y410 laptop . when i start my . Laptop lcd back light on but not show any image on the lcd and i hear the window opening sound but still i cant saw any image . Laptop fan is spain proper i also check it is not inverter problem plz help me.
December 21st, 2010 at 10:26 pm
Hello Sir,
I have Hp Pavilion Laptop ,model no. is dv2000.
I am getting one problem while start the system
then only sound is coming but display not showing
display showing as multi lining display after
few hours 4-5 i will check then display showing
properly so please give best idea to resolve my
problem.
Thanks!
October 5th, 2010 at 8:00 am
Mike Walsh,
Take a very close look at the laptop screen when it goes black. Do you see a very faint image on the screen? You might use a flashlight.
If the image is still there, most likely this is either the screen inverter or backlight lamp failure.
You cannot tell which one is causing the problem without testing the laptop with another known good inverter OR backlight lamp.
Here’s how to disassemble the IBM ThinkPad display panel and access inverter board.
If you have no spare parts and have to guess, try replacing the inverter board first.
If the problem is still there, probably this is backlight lamp failure. In this case you’ll have to replace the LCD screen.
September 9th, 2010 at 8:46 am
I have an IBM R51, The screen flickers occasionaly and goes black occasionally. When I hit the Fn F7 button (sometimes a few times) it comes back up and works fine(external monitor/none attached). I have updated all the drivers, run multiple virus scans, now I’m thinking hardware issue. Looking at the posts above, I’m thinking it could get complicated/expensive. Any advice you can offer would be greatly appreciated. It’s runing XP pro, service pack 3, machine type 1836.
Thanks
Mike