This laptop came for repair because of the LCD screen backlight failure. My customer complained that the laptop LCD screen is black but the laptop works with an external monitor.
Here are my steps for troubleshooting this laptop with the backlight failure.
First of all, I tested this laptop with an external monitor connected to the VGA port and the external monitor worked absolutely fine. I was able to get crystal clear image on the external screen even though the internal screen didn’t light up. If the external screen works fine, then most likely there is nothing wrong with the video card.
Notebook display assembly diagram
After that I took a closer look at the laptop LCD and noticed that the screen is not completely black. The laptop screen still works but the image is very very dull, you barely can see it. It means that the screen still gets data signal from the video card, but for some reason the backlight lamp doesn’t work.
From my experience I know that this problem can be related the lid close switch, faulty inverter board or bad backlight lamp. I checked them one by one.
If you have a similar problem, make sure the lid close witch moves freely. The lid switch is a small button located close to the LCD screen. This button triggers the hibernation or sleep mode when the screen is closed. If the lid close switch is dirty, it might get stuck inside the laptop case and cut off the power from the inverter board. The inverter board works as a power supply for the backlight lamp and if there is no power coming to the inverter board, the backlight lamp will not light up either.
In my case the lid button worked properly, it didn’t stuck inside the case. When I was pressing on the button very fast, I was able to light up the screen but only for a fraction of a second. The image wasn’t bright and it had a pinkish tone. A pinkish tone usually indicates a problem with the backlight lamp, not the inverter board.
Even though I suspected the backlight failure, I decided to test this laptop with a new inverter board just in case. But it didn’t help. The screen didn’t light up even after I replace the inverter board. So, I was right, this problem is not related to the inverter board.
Finally, I disconnected the screen backlight lamp connector from the inverter board and connected my test backlight lamp (I removed it from another cracked screen). For the test purpose, you can buy a new backlight lamp here. Try to find a backlight with the connector already attached to it, so you can plug it into the inverter board. Make sure the connector on the backlight lamp is similar to the connector on your LCD screen.
As soon as I turned on the laptop, my backlight lamp lighted up. Yep, that’s the problem. The laptop screen has a faulty backlight lamp.
Here’s another laptop with backlight failure
This laptop video fails in a little bit different way. In this case the backlight lamp hasn’t failed completely.
The laptop starts with video on the screen but the background has reddish tone, the screen flickers and it makes noticeable buzzing noise coming from the backlight and inverter area. After a few minutes the backlight turns off by itself and the buzzing noise stops. When the backlight is off, the image on the screen is still visible but it’s very dark.
I removed the screen bezel and connected my test backlight lamp.
My test backlight works absolutely fine. The lamp doesn’t flicker and there is no buzzing noise. So, this laptop needs a new backlight lamp.
If you find this article useful, please consider making a donation to the author. Thank you!
April 24th, 2010 at 12:47 pm
benjamin asare-humi,
I like your troubleshooting steps. You did everything correctly.
It looks like your problem is not related to the backlight lamp or inverter. You tested them and both work properly.
Apparently, in your case this is the motherboard failure (more likely) or LCD cable failure (less likely).
Maybe the LCD cable is damaged. You can try replacing the LCD cable. If the problem still exist, most likely there is a problem with the motherboard.
April 22nd, 2010 at 12:45 pm
hello
i have a problem with my fujitsu siemens laptop. the screen wont light up but i can see the image in the screen. i took out the whole screen and tested it on another laptop and it worked perfectly which means there is no problem with the screen. i changed the inverter and the light came on but it was dim. and then later it went off completely. i’ve tried different inverters but still its not coming on. but when i try that same inverter on another laptop it works perfectly. please help me.
April 12th, 2010 at 7:43 pm
thank you so much for this info. You helped me save a couple of hundred bucks, from some tech, who told me there were a bunch of things wrong with my monitor. It was just the switch. THANK YOU.
I am considering buying the video series. Thanks again.
April 6th, 2010 at 5:59 pm
HELLO
I HAVE ACER ASPIRE 4710Z LAPTOP IT GIVES SOME PROBLEM WHEN I TURN ON THE LAPTOP IT SHOWS WHITE SCREEN DOESN’T SHOW ACER OR WINDOWS . LAPTOP WORK BUT EVERY THING IS WHITE IT GIVES WINDOWS STATUP TONE ALSO . WHEN I USED TO LOG OFF & START AGAIN THAN IT WORKS PROPERLY
March 29th, 2010 at 11:04 pm
This article gives me some hope but doesn’t answer my real problem. I have a workhorse Dell Inspiron 8500 laptop with a very recent issue. On start-up the windows splash screen and booting bar are shown fine on laptop screen (so can’t be backlight?) but it then goes black (not dim) – however on remote screen it continues to boot and show desktop all OK. It is not an F8 problem; I’ve checked switch and this is OK; been into laptop Display in safe mode and it doesn’t recognise that laptop screen exists. Any thoughts/ ideas for a non-techie to try??? Any help much appreciated.
March 18th, 2010 at 9:01 pm
I have this laptop it’s a Compaq presario cq60.
The monitor was sat on so it’s not good, I took a display out of an older HP the inverter and cable connect does not match, so I am attempting to try to splice the wires, but there are so many and all different colors….
what do you think?
January 29th, 2010 at 4:33 am
thank you so much (in my tongue = terima kasih banyak) for your article this help prevent me from buying another inverter or backlight or even a new lcd screen
after reading I encorage myself to look into the lid switch only to find that it’s half stuck meaning if you close the lid it enter hibernation, but if it stuck halfway it only turns off the backlight.
I’m a fool for not checking the lid switch, I was really certain that this is an inverter or a backlight problem.
this case really adds my experience in laptop handling.
advise for newbie: CHECK THE LID SWITCH BEFORE DISMANTLING YOUR LAPTOP!!!!!
January 27th, 2010 at 11:11 am
Hello,
I have fujitsu siemens amilo v2010. The image on screen is very dimm. I tried good known backlight lamp, and it is not working. Replaced with new inverter, also no luck. Image is very dimm like backlight failure. Could it be video cable or bad motherboard?
December 27th, 2009 at 6:24 am
Hello
Have a Compaq Presario C500,when turn it on,screen stays on for about 15 seconds then turns off but there is very faint image…have not tried external monitor (next step),do you know how to get disassembly directions fot this laptop?
December 15th, 2009 at 7:22 am
My problem is a little different from others I’ve read. After turning on the unit and heating up for 10 minutes, I get a small semi-circular black spot that appears in the lower right hand corner of the screen. It appears as about the size of a thumb print. It will remain and after the unit runs for additional 10 minutes or so, the screen will start to “flicker” and become distorted. I have not just left it on to see if it will go totally black. After shutting off and cooling then restarting, the screen is clear until it warms up again. Would this be the inverter or a screen problem?