Do you have a problem with the backlight on your laptop? If yes, you are not alone, that’s one of the most common laptop problems. In most cases the screen inverter is the culprit. Here are some LCD screen backlight failure symptoms that could be related to a bad inverter board:
- Laptop boots as usual but after some time the screen blacks out. You still can see an image on the screen but it’s very dim. You might even use a flashlight to see it better. Sometimes the backlight comes back for a while but then goes off again. In some cases you can turn the backlight on if you tap rapidly on the lid close switch.
- The screen always stay black and the backlight never comes on but you still can make out an image on the LCD. It’s dark, but the image is still there.
-In some cases you might hear a buzzing noise coming from the area where the inverter board is located, it’s on the bottom part of the display assembly.
NOTE: if you cannot see an image on the screen, most likely you have a different problem and there is nothing wrong with the screen inverter.
Other related articles:
Laptop has bad video on the LCD screen. What is wrong?
Notebook display assembly diagram. How image appears on the screen.
How to troubleshoot and fix laptop video problems
How to replace laptop backlight lamp (CCFL)
Here’s an example of replacing the FL inverter board on an IBM ThinkPad T41 notebook. This guide will work fine for any other IBM notebook. Replacing screen inverter on other notebooks like Dell, HP, Toshiba, etc… will not be much different.
First of all, unplug the AC adapter and remove the battery.
In order to access the inverter board you’ll have to remove the LCD screen bezel. On most laptops screws are hidden behind screw seals. In this case we have 5 screw seals on the front. Carefully remove the seals with a sharp object and glue them on the LCD bezel, in this case you will not lose them. Remove all screws and mark them somehow so you are not confused when you assemble the notebook back.
Some laptops also have screws on the side of the display. This notebook has 3 screws on each side. Remove screws seals and then remove screws.
Start removing the LCD bezel with all fingers. Carefully wiggle the bezel to release plastic latches. Never use any sharp object during disassemble because you can accidentally damage the screen.
If latches are very tight you can use a guitar pick to unlock them. Insert the guitar pick between the LCD bezel and cover and carefully move it alone the side.
This notebook allows you to replace the inverter board without removing the LCD bezel completely. Lift up the bottom part of the bezel and remove one screw securing the inverter board to the LCD cover. This location is very common for the screen inverter. On most laptops you’ll find it under the display bezel below the screen.
Carefully lift up the FL inverter and rotate it a little bit. Unplug cables on both sides. The left side of the inverter board connects to the video cable, the right side to the backlight bulb (CCFL tube) inside the LCD screen. Remove the inverter and replace it with a new one.
To find a new inverter board (and any other spare part too) for any IBM notebook you should use the FRU number from the part.
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April 9th, 2009 at 8:06 am
Alan,
First of all, check the lid close switch – a small button located close to one of the display hinges. Make sure the button moved freely and is not stuck inside the case. Can you make the backlight flash if you tap on the lid close switch?
If tapping on the switch doesn’t help, apparently there is a problem with the motherboard.
Also, you may have a defective video cable.
I don’t know what else could be wrong. It’s either bad cable or motherboard.
April 7th, 2009 at 3:45 am
hello,
My X40 screen has gone black, and i don’t know whether it’s the inverter or the back light. how can i figure this ?
Also i have a asus m5 which is dead. Can i user this screen and the associated inverter on the x40 ?
April 5th, 2009 at 10:13 pm
I have replaced the LCD (twice) and the inverter (3 times!) on my IBM R51 – screen’s black but working -I can see a faint image.
So I guess the motherboard power to the ibnverter’s the problem – is that diagnosable or fixable?
March 31st, 2009 at 10:54 pm
Robert Folkes,
It’s either bad inverter or faulty backlight lamp.
I doubt that you can test the inverter board with a regular voltmeter. I’ve been looking for a good reliable method to test inverters with a voltmeter for a long time and haven’t found one yet. As soon as you attach the voltmeter to the inverter board, it shocks the system and the laptop stops working properly until you restart it. That was my experience with testing inverters. The only reliable way is installing a known good inverter board or attaching a known good backlight lamp.
That means you have a problem with the backlight lamp inside the screen. Also, there could be a problem with the motherboard or video cable but it’s not common. My guess, it’s either defective inverter or bad backlight.
That’s right, it works correctly only when it’s loaded – the backlight lamp is attached.
Not at all. Try replacing the inverter again. If you still experience the same problem, move to the backlight lamp.
March 31st, 2009 at 10:43 pm
My Advent 7108 goes dark after a couple of seconds, but if I look really carefully I can still see the graphics, cursor moving etc and the atatched monitor works fine. If I toggle between the monitor and the laptop screen the picture comes back for a couple of seconds. I see a high voltage on the output of the Darfon inverter for a couple of seconds (not not long enough to get a stable reading on my DVM).
Classic inverter problem you may say, but exactly the same thing happens with the replacement inverter. Have I just been unlucky and the repalcmeent unit (sold as tested and working) has exactly the same issue as the original?
I don’t see how it can be the screen since the inverter cannot sustain an output voltage with the screen unplugged.
Am I being unreasonable to expect the supplier to send a replacement or refund?
Thanks in advance
Robert
March 31st, 2009 at 9:01 pm
michael,
1. Could be defective inverter board.
2. You have a faulty backlight lamp. If that’s the case, you’ll have to replace the LCD screen. You can try replacing the lamp but it’s not easy at all and only for people with experience.
March 31st, 2009 at 8:57 pm
hi. so i just followed your instructions on how to take apart a toshiba a105 laptop screen to replace my inverter. i just got done replacing it (with a board from the ebay site that you suggested) and i rebooted my laptop it flickered a little bit and it stop being pink. but after a few minutes i heard a hissing noise and the screen all of a sudden died on me again being completely dim or complete darkness with some windows being visible if i use a light on it. any suggestions?
March 24th, 2009 at 6:33 pm
Bottom third of screen blacked out on a HP Pavillion ze4900?
March 22nd, 2009 at 9:02 pm
ok I took everything a part andpulled out in inverter to get the number now having trouble finding a place that will sell it …is ir possible it can be the bulbs that are making the screen dim? and if so how do I change those and find out what kind of bulbs I need?
March 10th, 2009 at 3:31 am
can i just remove the laptop monitor and replace it with a regular monitor.. i have a flat screen 21inc monitor.. is that possible?