Screen inverter board
Laptop inverter boards (also know as LCD inverter, FL inverter, screen inverter, backlight inverter) come in different shapes and sizes. On the picture above you see some typical looking inverter boards found in laptop computers.
The 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) supplied by the motherboard to high voltage AC power (few hundred volts) needed for the backlight lamp.
When the inverter board works properly, the backlight lamp gets power and the LCD screen lights up. As a result, the image on the screen is bright.
HOW INVERTER CONNECTED TO LDC SCREEN
On the picture below you can see a typical laptop display assembly which includes the LCD screen, video cable and inverter board.
One side of the inverter board connects to the backlight lamp and another side to the video cable (LCD screen cable).
HOW INVERTER MOUNTED INSIDE LAPTOP DISPLAY PANEL
In most laptops the inverter board is mounted below the LCD screen as it shown on the picture below. You can get an access to the inverter board when you remove the screen bezel – a plastic frame around the LCD screen.
TYPICAL INVERTER FAILURE SYMPTOMS
Usually inverters fail in one of the following ways:
1. When you turn on the laptop, the screen lights up for a short period of time and then goes dark. You still can see an image but it is very dark, almost invisible and definitely not usable. When you restart the laptop, the screen lights up and then goes dark again. The laptop works fine with an external monitor.
2. Your laptop turns on but the screen remains dark all the time. You still can see a very dim image outline. The laptop works fine with an external monitor.
3. The laptop screen works fine for hours or even days, but sometimes it goes very dark as it mentioned above. When you restart the laptop, the screen works fine again.
Inverter failure symptoms are very similar to backlight lamp failure symptoms and in most cases you cannot tell which one is causing the problem until you replace either the inverter board or the backlight lamp. From my personal experience, inverter boards fail more often than backlight lamps. If you have to guess, replace the inverter first.
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October 11th, 2009 at 11:58 pm
Hey, I have an HP Pavillion dv6000 laptop and I had a screw fall out of the back of it and the screw was connected to the monitor. So I was moving the monitor around quite a bit to fix the screw. When I was moving it around the screen went almost completely black. So now I can see very faint images on the screen but they are almost invisible and almost completely black. I was wondering if you think this is the Blacklight lamp or the Inverter Board or possibly something else. My computer is no longer under warranty and it is also my work computer so I am freaking out and want to fix it myself and not tell my boss about the problem. Any help would be much appreciated!! Have a wonderful night!
October 11th, 2009 at 12:09 pm
steven,
The video works fine on the external monitor, so there is nothing wrong with the laptop or software.
You are using different cables for the TV and external monitor, correct? I think the cable running from the laptop to the 22″ TV could be bad or not plugged correctly. Try reconnecting the cable and if it doesn’t help, try another cable.
October 11th, 2009 at 11:44 am
I have a brand new high end Dell laptop funning Vista. I want to use an external 22″ monitor with it. When I plug in the monitor, the screen has a pink tint. I have tried everything but cannot do anything to make this go away. I plugged the monitor into a desktop (running XP) that I have and the screen looks fine. Any ideas???
Thanks in advance.
October 10th, 2009 at 1:40 pm
Julie,
Congratulations! I’m glad that my site helps people.
October 10th, 2009 at 1:39 pm
Hally,
I does sound like a problem with the video card.
You said the laptop works fine for now, but most likely it will fail in the future.
After you mentioned vertical blueish lines in a regular pattern on the external screen, I’m 99% positive that you have a faulty video card.
October 10th, 2009 at 11:27 am
Mike,
That means the motherboard and video card work properly.
Again, as I mentioned in my previous comment, it’s not related to the inverter.
Try reconnecting the cable first, could be just loose connection.
October 10th, 2009 at 11:25 am
Mike,
First of all, your problem is not related to the inverter board. When the bottom 2/3s’ of the screen fails, you still can see the rest of the screen. That means the inverter powers up the backlight and works properly.
Your problem could be related to:
1. Loose connection between the video cable and LCD screen. You can remove the keyboard bezel and try reconnecting the video cable. Here’s a guide for Vostro 1510 notebook, could be similar to yours. Take a look at the step 7. The video cable connector in Vostro 1510 is located close to the left hinge.
2. Start the laptop while the keyboard bezel is removed. Now carefully move the video cable without moving/touching the screen. Does it affect video on the screen. If the video changes when you move the video cable, it’s possible that you have a bad cable. Apparently there is short inside the cable. Try replacing the cable.
3. Turn on the laptop and wait until video fails. Can you get it back to normal by moving the screen back and forth? Can you get it back to normal if you torque the screen a little bit? If yes, most likely you have a faulty LCD screen. You’ll have to replace the screen.
October 10th, 2009 at 10:44 am
Hally,
I really doubt that your problem is related to the LCD screen.
In your comment you said:
This sounds like a problem with the video card.
In a case of LCD screen failure, you still should be able to use the laptop with an external monitor with normal resolution, but you can use it only in Safe mode when only basic video driver is loaded.
I’m not familiar with your model. If the video card is integrated into the motherboard, you’ll have to replace the whole motherboard. If the video card is a discrete module, you can replace just the video card.
October 7th, 2009 at 1:20 pm
This post just saved my boyfriend’s dad $400.00!!!! The screen display was really dim but the computer booted up fine. So it turned out that the LCD battery back up thing was partially unplugged from the inverter. and all I had to do was open it up. Thank you so freakin much!
October 7th, 2009 at 12:46 am
Update @comment #148:
In the last days I didn’t even bother to try to use the laptop’s display anymore. I struggled with the external monitor, in safe mode. I then observed some vertical blueish lines in a regular pattern (about an inch between each group of lines).
I wanted to test this on another external display. It reproduced. Then I booted an Ubuntu from an USB stick. The line pattern persisted. I thought that the problem was with the video card.
But something happened in this stupid saga. Last night I connected again the desktop monitor to the laptop and booted from an Ubuntu USB stick. It didn’t show the line pattern. Then I bootted from the HDD (Win7) in normal mode (previously, it worked in safe mode only). Again, surprise, it worked. Then, I disconnected the external display and tryied to use the laptop’s display. It worked again!
Right now, I’m writing this from my laptop, using its display. It behaves like nothing happened in this last week. Well, almost – the same freaking WHEA errors continue to appear (WHEA-Logger EventID 19, 18). I’m expecting a failure anytime.
Anyway, it seems I’ll eventually have to buy another laptop (this time it won’t be Acer/AMD/nVidia; I’m trying my luck with an Asus/Intel/Ati). Thanks for bothering with my messages.
October 5th, 2009 at 11:29 am
Oh – one more thing RE: intermittent LCD problem.
When this problem was occurring, I did hook up an external monitor and that display was fine, no problem. Happy enough to replace the LCD and/or inverter, but was curious if the intermittent nature was an indication of some other problem which replacing these would not remedy.
Thanks.
October 3rd, 2009 at 10:16 pm
I have a problem with a Dell Vostro 1400 laptop.
Recently, upon waking from standby, the bottom 2/3’s of the LCD is covered by close-together horizontal lines. This problem is resolved by a shut down and restart. However, it recurs when the unit goes into standby again.
Easy enough not to allow the machine to go into standby, but concerned this is an early indicator of something worse component wise starting to fail.
Did not know if this was an indication of the inverter starting to go, or if the standby problem indicates something more related to the video card or some other problem…
Any suggestions on where to start/test?
Thanks.
October 2nd, 2009 at 12:17 pm
Hello,
A few days ago, without any warning sign, after almost two years of trouble-free operation, my laptop screen started to flicker until it finally settled to a gray color, with barely visible vertical stripes.
I stopped it forcefully (by pressing the power button for a few seconds). After restart the same gray screen appeared right from the beginning. When I left it turned on, the screen gradually changed color to a blue-green shade (resembling the one from Windows 7’s logon screen).
Later that day, when I restarted the laptop, all went ok, at least for a while. After some two hours of operation, the flicker happened again and all the symptoms were back.
I plugged in my desktop’s monitor and after displaying the Win7 bootscreen it returned a BSOD (nvlddmkm.sys). Afterward I could get it to work somewhat reliably only in safe mode with networking support.
Before any subsequent start of the laptop, I first tryied using its own display. On several occasions it worked normally and for quite a few hours before it freezed.
I also started to get some WHEA errors in the Event log (WHEA-Logger EventID 19 Warning A corrected hardware error has occurred, WHEA-Logger EventID 18 Error A fatal hardware error has occurred.)
I then tryied uninstalling/reinstalling the drivers for the chipset (nforce 7000M) and video adapter (nVidia 8600M GS), all without any positive result.
I also suspect these problems might be related to heating issues (the video chip is rated at ~70-80 C).
I took a look inside the laptop’s display and there were no apparent signs of damage to any of the components.
Now, I can use it only connected to the external monitor and only in safe mode. If I try to use the laptop’s own screen, it only displays the vertical gray lines that eventually turn blueish after leaving it on for a couple of minutes.
My biggest concern is whether to buy a new Acer screen or a new laptop alltogether. I thought that by describing these details to you, you might have some clues in order to pin down the issue and make a decision.
I’m sorry for this long message. I’d appreciate your help.
Thank you.
My specs:
Acer Aspire 5520G
AMD Turion 64 X2 TL-58, 1900 MHz
nVidia nForce 7000M-610M (southbridge), AMD Hammer DDR 2 IMC (northbridge)
2048 MB RAM
nVidia GeForce 8600M GS, 512 MB GDDR2
Acer CrystalBrite 15.4″ LCD (LG Philips), WXGA
Windows 7 Ultimate 64bit (worked fine for around a month before this whole thing happened)
October 1st, 2009 at 12:45 pm
zigymantas,
There is a backlight lamp mounted inside the LCD screen, it’s on the bottom of the screen. When the backlight lamp is on, it generates heat.
It’s normal when the bottom part of the display panel is warm. It’s getting warm because of working backlight.
By the way, the inverter board also generates some heat when it’s on.
October 1st, 2009 at 12:15 pm
Dan,
I don’t think that your problem is related to the inverter board because it flickers only when you move or adjust the display. With a failed inverter the screen would be black all the time.
It sounds more like a connection related issue.
Here’s what you can try:
1. Try reconnecting video cable on the back of the LCD screen. Maybe the cable doesn’t make good connection with the screen.
2. Try replacing the video cable. It’s possible you have a short inside the cable.
3. Could be LCD screen failure.
October 1st, 2009 at 4:51 am
Hey Repairman,
I have an HP DV5000, sometimes when I move the screen, either to close it or to adjust it’s position, the screen flickers. It usually only happens if I grab the sides of the screen. I’m not sure what this could be, I tried changing the inverter, but apparently the one I ordered online is the wrong one because the backlight would come on for about a second then the screen would go dark, I put the old one back in and it works fine, but I still have the flickering problem. Before I go crazy trying to find the correct inverter for this machine, do you have any other suggestions?
September 29th, 2009 at 8:34 am
or maybe this is a reason of a backlight lamp, cause, as i realized, its located in the bottom of the screen?.
September 29th, 2009 at 2:34 am
hi..i found more intresting information about this part of a laptop.
however, one thing i want to know – when this “Screen inverter board” works normally, does it rise temperature, cause the part in my laptop under the “HP” logo on screen gets warm, and, of course, it rise tempereture of lower part of the display.
September 28th, 2009 at 8:38 am
Thanks Repair Man. I will get a LCD lamp (with a small plug in my case) from ebay to test with per your recommendation. I see some there for $20 with plug.
Also, I will test with multimeter, unless you think power is not likely the issue with my description.
Tom, per Repair Man verify if you can plug in an external monitor and get a normal picture. That will confirm if your video card is working. In my case it works fine and the PC seems normal. I’ve tried an inverter so my next step is to test the backlight. If it works, I’ll buy a new LCD screen for around $120.
Thanks again,
September 24th, 2009 at 6:10 pm
Tom,
Did she spill it on the keyboard or display?
If she spilled it on the keyboard, most likely the tea wend down to the motherboard and damaged it.
Let it dry for some more time. Do not forget to remove the battery. Who knows, it might start properly in a few days.