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.
Need spare parts for your laptop?
If you are looking for spare parts for your laptop you can find brand new and used parts here. Just search by the part name and laptop model.
July 25th, 2009 at 8:12 pm
Hey guys,
Awesome site you have here.
I currently own a Fujitsu Lifebook N6110. I had several strips running vertically on my screen so I bought a new compatible lcd screen. However when I took apart the laptop to replace the screen, I noticed that the original broken LCD had two backlight connectors, whereas the replacement only had one.
Can I just replace the original inverter with a new one that accepts only one connector? If so, what kind of inverter would be compatible? If not, what are my options (as I cant really return the LCD anymore)?
July 16th, 2009 at 10:03 pm
Chris, Jeremy,
Have you guys tried upgrading the BIOS to the latest version?
July 16th, 2009 at 9:59 pm
Alex,
Most likely it’s either bad backlight lamp or poor connection between the video cable and inverter/motherboard/LCD screen.
1. Try reconnecting the video cable. Make sure all ends are plugged in correctly.
2. Try replacing the LCD screen.
I don’t think that you can damage the inverter board by dropping the laptop. Most likely you’ve damaged the backlight lamp.
You can buy the entire display assembly (LCD and inverter) on eBay for about $50-60.
July 13th, 2009 at 9:22 pm
Hey Chris,
Thanks to the power of Google I found your posts about your Vaio-AR series. I think I am having the exact same symptoms… it is very dim compared to how it used to/should be… I am getting a brightness reading of 120 cd/m2… according to specs it should be in the neighborhood of 300 cd/m2. I am very interested to see if you find any solution to the problem.
I have a Vaio VGN-AR390E with the 1920×1200 WUXGA and the low-brightness is driving me crazy! I hope you or the repairman has some insight.
Thanks!
July 13th, 2009 at 12:32 pm
Hello, I’m trying to fix my old Inspiron 600m that fell from 3 feet and the LCD display is not working since. I found out that it works with external display so I pretty much narrowed the problem to broken inverter or backlight lamp. However, I also found out that while the screen looks entirely blank, when you look at very sharp angle (and using a flashlight), I can actually see the laptop screen. Does this give me any additional information — i.e. whether the problem is inverter or backlight lamp? Thanks a lot!
July 8th, 2009 at 2:29 am
Ok. I’ve put it apart. LED logo is a separate circuit so it is unrelated to backlight. Both lamps seem to work. I unconnected one after another from the inverter board and the result was the lamp ignited then after a brief moment turned off completely. Each lamp did the same. So I guess both are working but the inverter refuses to run with a single lamp only. I am on my way to order a new ccfl tubes and replace the backlight, but I am usnure about certain things.
- Since my laptop is working I haven’t attempted to pull out the ccfl tube and to measure it. The screen diameter (across all visible pixels rather than glass) is 432 mm (that is 17″, not 17.1″). The lcd panel active area is 367 mm wide. Now, there are two tubes, which are recommended for this screen: one is 370 and the other is 375 mm. Which one should I get – I guess that 370 should be better, but I’ve seen somewhere the 375 mm to be recommended for my screen.
- Another thing is should I also consider other tube parameters (like ignition voltage / running voltage – or are they just linked to tube length and diameter) and more important – the colour temperature. The screen now (although somewhat dim) is pleasantly warm, reds and skin tones are rendered very naturally. I am a little bit afraid that when I get two new and bright 9000K tubes I loose that fine colour rendition capability. I do not do heavy photo-editing and stuff, but I shoot a lot of pictures and would like to look them good on my screen.
What do you think?
July 3rd, 2009 at 5:57 am
That’s 17″ vaio AR with wuxga+ double lamp – no brightness settings in BIOS. Decreasing/increasing works ok – but the screen on the highest settings is pretty dark, like it should be on the lowest setting. I’ve also noticed that the place where the inverter is (presumably – I haven’t opened the screen yet) – under lcd, in between speakers, close to the vaio logo gets pretty hot. I mean I can touch the bezel and keep my hand there, but I feel it is hot. Right now its 82F indoors so maybe that’s why it gets so hot. I don’t know… The vaio logo is also dimmer compared to what I’ve seen on another unit (another AR, different series though). I don’t know if the logo LEDs are on the same PCB as inverter. If this is the case – that may indicate that the inverter has some voltage deficiencies? I have a multimeter and a scope and I can measure voltages/frequencies on the inverter, but don’t know what values to expect, etc.
July 2nd, 2009 at 10:44 am
chris,
What laptop did you buy? Did you check settings in the BIOS? Maybe you can change the LCD screen brightness in the BIOS?
What if you try decreasing the brightness, does it work?
July 2nd, 2009 at 9:38 am
Hi I just bought a second hand laptop and I’m having the same problem. The screen is not “as bright as it should be”. The laptop is approx 2-3 years old. Fn+F8 is all the way up.
I’ve been wondering whether that’s something with the inverter or the lamp.
You say that bad inverter means fickering or bklight completely off. But I wonder whether the inverter may have suffered some kind of ageing and is not supplying enough juice to lamps. Like the wrong voltage/frequency/duty cycle,… dunno. Is that possible? I guess it is either the inverter or the lamp. But my laptop has two lamps and the screen is backlit evenly so I doubt they’d both could fail in the same way.. What do you think?
May 27th, 2009 at 8:51 pm
Dorji,
Have you tried to increase the screen brightness using Fn+F8 key combination? Press and hold down the Fn key and at the same time tap on the F8 key. Could be just a problem with the settings.
I don’t think that 2 years is a long time for the backlight lamp. My laptop is over 4 years old and I use it every day. The screen is still bright as before.
Replacing the inverter board will not help. That’s for sure.
May 27th, 2009 at 12:09 pm
Hi,
I have an HP pavilion DV6000 notebook bought in February, 2007.
I have noticed that the screen brightness is not what it used to be when it was new. It’s a little dimmer when compared to new notebooks these days.
They say LCD screens lose their brightness overtime and mine’s been more than 2 years of heavy usage.
If that’s the case, what can I do to bring up the brightness to the level it was when it was new. Do I have to change the inverter or the backlight lamp.
Thank you in advance.
May 8th, 2009 at 9:03 am
Michael,
Isnt’ it strange? I notices that too. Sometimes it’s cheaper to replace the whold display assembly than just the LCD screen.
May 8th, 2009 at 8:36 am
I had a problem with backlgith in my Dell Latitude D610 notebook. The screen was bright only for about 1-2 minutes on startup and after that it was turning very dark. If I reboot the notebook it was doing the same.
I wasn’t sure if I had a bad inverter or backligth and instead of replacing them one by one I replaced the entire display which included the screen, inverter, cable, plastic covers, etc…
I found a good used display on eBay for less than $70 and it was cheaper than the new screen!
The replacement took me about 30 minutes and it was easy. Works great!
May 7th, 2009 at 9:12 am
adeel,
It’s hard to tell what is wrong in your case. The inverter and backlight fail the same way and have the same failure symptoms.
You said that in times only one corner of the screen is lit. I think you have a faulty backligth lamp. When inverter fails, it usually fails completely and there is no light on the screen at all.
You can buy an inexpensive backlight lamp and test your laptop to make sure it’s the backlight failure. The procedure could be found in the following post: How to test LCD screen inverter in a laptop
March 7th, 2009 at 10:56 pm
hi i have a acer aspire 5920 my back light flikers on and off sometimes its on completly and others its off. other times only one corner of the screen is lit. what do u think is worng.(backlight lamp and/or inventer. pleas help me.
February 3rd, 2009 at 10:25 pm
James,
The backlight lamp is not expensive, you can find it on ebay for $10-15 but it’s very hard to replace the lamp. You’ll have to take apart the LCD screen.
February 3rd, 2009 at 8:49 pm
Is this lamp expensive? Where I can find a backlight lamp for a laptop?
February 3rd, 2009 at 11:44 am
Tim,
1. Could be loose connection between the cable and inverter board. Try reconnecting the cable first.
2. It’s possible you damaged the backlight lamp and the LCD screen has to be replaced now.
February 3rd, 2009 at 8:25 am
I accidentally dropped my Dell XPS laptop from a 2 foot table. I was lucky because it landed on the carpet and now the screen didn’t crack but it will not light up. The laptop turns on and starts but the screen is so dark that it really hard to see anything. Do you think I broke the screen lamp?
January 14th, 2009 at 11:42 pm
[...] inverter board works as a power supply for the backlight lamp mounted inside the LCD screen. The inverter board converts low voltage DC power (few volts) [...]