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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January 19th, 2010 at 11:21 pm
Sam,
You said the screen is dark, but the image is still there, correct?
Most likely you damaged the backlight lamp.
January 19th, 2010 at 11:06 pm
C,
Most likely this is not related to the graphics card failure. A failed video card would affect image on the entire screen, not just a part of the screen.
Just in case test your laptop with video on the external monitor. If the external video works perfectly and there is no pink glow/splash/tint, the problem is not related to the graphics card.
I think it’s either failing backlight lamp inside the LCD screen (more likely) or failing inverter board (less likely).
From my experience, when the inverter board fails, the backlight lamp stops working completely. In your case only one part of the screen is affected, so I assume this is the backlight lamp failure.
January 19th, 2010 at 11:01 pm
JahJah,
First of all, I would check laptop memory (RAM). Most likely you have two memory modules installed and it’s possible that one of the modules failed.
Try removing memory modules one by one and test the laptop with each RAM module separately in each slot.
I believe when the drive is working the light is always amber, it never turns green. Isn’t it?
Remove the DVD drive and turn on the laptop. Maybe the DVD drive is bad and shorting the whole system somehow. Just a guess.
January 19th, 2010 at 11:15 am
Hi! I have a Toshiba A135 S2266 laptop. The powers light on the computer itself comes on and the fan starts up just fine but the screen stay blank both internally and externally and the light on the cd drives is amber instead of green. The cd drive will not open when the eject button is pressed, it only open when i put a pin in the little hole on the side. Could this be a problem with the motherboard, memory or inverter. I have opened it and double check all the wires and the MB, they look fine and have no burnt scent. Please help me, i’m in dire need.
January 19th, 2010 at 10:16 am
Hey guys,
Can someone help me with my laptop problem? I’m wondering if this is a graphics card problem or a screen inverter board problem.
On the side left of my laptop screen and sometimes on the left half of the bottom screen, there’s a pink glow/splash/tint. It’s gotten longer over the past week.
January 18th, 2010 at 1:56 am
Hello there.
thank you for a very informative site.
i dropped my laptop a few weeks back and I’ve had the dark screen problem ever since.
I’ve tried reconnecting the cables for the FL inverter but I don’t have good results. Display is fine on an external monitor.
I just want to know if it is possible to pinpoint the broken hardware (inverter or lamp) by the way it messed up i.e me dropping it.
I would also like to know how compatible inverters are. The one i’ve got is j9084 1.00
Toshiba satellite.
Thank you again mate.
Sam.
January 9th, 2010 at 11:05 pm
Hello!my acer aspire 4715z laptop shows blank screen after power on..everything is fine except the blank display..however,there are still back lights that light up in the monitor..what this could be the problem?thanks for the help..
January 4th, 2010 at 11:27 am
Thanks for all of the images and instructions. From the looks of it, my HP Pavilion dv6565 has a bad inverter. Where would you recommend purchasing a replacement part?
January 1st, 2010 at 3:32 am
Hi-I have a HP DV6000. The screen has a pink/red tint from the moment I turn it on, even before Windows loads. Do you think the backlight or the inverter or LCD screen is causing this problem? I reseated the display connector on the motherboard but that didnt fix the problem. Thxs. (BTW, the image is clear not fuzzy).
December 22nd, 2009 at 12:52 pm
alright i just replaced the lcd screen on my laptop which is a dell inspiron 4150 the inverter is working but there is no pictureand a blank screen but there is glow in the back
December 22nd, 2009 at 12:46 pm
alright i just replaced the lcd screen on my laptop which is a dell inspiron 4150 the light shows up and you can see the backlight working but there is no picture a blank screen
December 16th, 2009 at 1:18 am
Hello , i have a question about the inverter failure , but i think it’s not a lamp or inverter , but the motherboard failure, so it’s my “white hair” problem…
the backlight fail in random situations , so, can’t be the lamp becouse it works for hours and inverter too…
sometimes the backlight comes to blink a lot and comes off , i test all cables , connectors , all “mechanical” parts, all ok, now after read this experiences i try to check the pin1 and get 20v , pin2 and 20v , pin3-2v , pin4-0v , pin 4 and 5 is ground, i check possible bad resistors, caps, solders, and seems to be ok , to solve this , i need help to understand a little deep how this inverter works to find a way to get my backlight ok again
i think this voltages are wrong , the motherboard is possible sending a impossible value to inverter bright adjust on pin 2-3 and the inverter goes off, the model of inverter is VA250E – G75-0.3 on white label and LM10W ver 0.3 silked on inverter.
i want to know if i can change the source of pin1 to get a stable 15v and don’t connect pin 2-3 i can get the backlight on again with this inverter, thank’s!! sorry for my very bad english.
December 2nd, 2009 at 4:58 am
Blank screen when I turn on the laptop. DV9000 w/Vista.
Screen is lit. I can change the contrast Lighter or Darker. Laptop works with external monitor, but I cannot get it into safe mode.
Would it most likely be the inverter or the screen? There are images.
Any suggestions…
November 28th, 2009 at 12:11 pm
Costas,
Try searching on eBay using the laptop model number and part name. For example, if you have a Acer Aspire 5100, search for “Aspire 5100 inverter”.
November 27th, 2009 at 12:28 pm
I came to the same conclusion that you did and decided to buy a backlight for testing. As soon as I did that, it seems like the display has healed itself (so far about 6 successful reboots in a row). Once it starts acting up again, I will get a backlight and test it. If the screen’s backlight is bad, I will try and replace it…and if I screw up the screen, I will buy a new screen thru eBay. If the test backlight works consistently, then I will probably do what you suggest and replace the screen with one thru eBay.
Thanks for all of your help and guidance.
Barry
November 27th, 2009 at 11:50 am
Ok Everything ok with the removal of the lcd inverter,
but please cannot find this lcd inverter:
PWB-IVC12138T/B1-E-LF
any help please where to find it (I have google it)?
November 26th, 2009 at 2:04 pm
Barry,
It’s very unlikely that all inverters are bad. Most likely there is a problem with the backlight lamp.
I don’t think that your problem is related to the motherboard failure because the LCD screen works intermittently. I would test the laptop with another backlight lamp first.
Check out LCD screens on eBay. Some brand new LCD screens are very inexpensive. You can find a new one for about $100.
November 23rd, 2009 at 3:55 pm
Hi Repairman. An update. I tried the cable wiggling test with the bezel removed. No effect on the display.
I tested the input voltage to the inverter and it was 15 volts DC whether the display was working or not.
The “guide” link you noted in your last response is the test I did to test the inverter output..but I used an oscilloscope instead of a multimeter. The test gave me consistent results…a stable 55 kHz output when the display was working, and no output when the display was not working.
It really looked like it is the inverter. But since then I have replaced the inverter (twice) and there was no change in the symptoms…the display works sometimes and not at other times. Maybe your hypothesis about the LCD having to “load” the inverter is correct?
You speculate that the problem might be a motherboard failure. What part might it be, considering that it always works on an external display..and it always sends the proper 15 VDC signal to the inverter?
Finally, I really don’t want to buy a backlight to do that inverter test. It know that I will wind up breaking the light and producing a hazardous mess from the mercury inside. Considering that I have tested 3 inverters and the symptoms don’t change, I have to believe that the problem is elsewhere…and probably the LCD itself. I won’t invest another $300 or so into this computer for a new 17″ display. So for now I will thank you for your suggestions, and continue to limp along with the computer as it is.
Thanks,
Barry
November 19th, 2009 at 8:11 am
Barry,
Try that. If there is a short inside the cable, you should see changes on the laptop screen when you move the cable.
Are you talking about this guide? I tried that (even purchased a new Fluke multimeter
) but it didn’t work for me. By the way, I love my multimeter. 
I think the inverter board works properly only when it’s loaded by the backligth lamp. Yes, if the backlight lamp is working fine you can get high frequency readings. But what if the backlight is bad? I think in this case you will not get those high frequency readings even if the inverter is good, because it’s not loaded. I could be wrong though.
… or the inverter board is not getting any power from the motherboard and there is no light because of that….
I think you can safely test voltage on the input. Yes, it’s pin 1 and ground. I did that. You should get something like 10-20VDC.
I’ve been fixing laptop for 5 years and here’s what I found. The best way to find out if you have issues with inverter or backlight lamp is testing the laptop with another known good inverter or backlight. Check it out: http://www.laptoprepair101.com/laptop/2009/05/04/how-test-lcd-screen-inverter-in-laptop/
Could be the motherboard failure. Maybe one of the components is failing. This component fails most of the time, but if it starts, it works properly until the laptop is turned off. That’s my guess.
November 18th, 2009 at 6:18 pm
Thanks for the reply, Repair Man. I have not tried to move the cable directly when the computer is on, but I have moved it indirectly. I have opened and closed the computer cover both during periods when the screen is not working and during periods when it is working. No matter how much I move the screen, it does not cause a non-working screen to work and it does not cause a working screen to stop working. Does that tell you anything? I am away from home until Friday. I will take the bezel apart then and see what happens when I move the cable directly.
I do have one new piece of information. I saw the reference to the person who recommended diagnosing inverter function using a Multi-meter with a frequency readout. If the inverter was working he got a strong, high frequency (30 – 50 kHz) reading when he held the probes in the vicinity of the inverter output. If the inverter was not working he got a weak or no reading.
I did a similar test using an oscilloscope. I found that during periods when the screen was working I got a strong (a few mV) 55kHz signal when I held the O’scope probe near the inverter output. During periods when the inverter was not working, I got not signal. So it looks like the inverter output is the issue. Doesn’t say if the problem is a bad inverter or a bad cable/connection to the inverter. But it is probably not the LCD itself (do you agree?).
What do you think of testing the input voltage to the inverter? That same person recommends testing between input pin 1 and ground. Shouldn’t that determine if the issue is the inverter or the cable?
Thanks again,
Barry