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.
Laptop parts | Repair Man | 
December 26, 2008 3:14 pm
440 Responses to “Screen inverter board”
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Pages: « 18 … 13 12 11 10 9 [8] 7 6 5 4 3 … 1 » Show All
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
November 17th, 2009 at 11:49 pm
KomS,
As I mentioned in the previous post, if the laptop is working fine with external monitor but internal LCD is BLACK and BLANK, check the video cable.
1. Could be bad connection. Try reconnecting it on the motherboard.
2. Could be bad video cable. Try replacing the cable.
November 17th, 2009 at 11:40 pm
Barry,
Most likely it’s either bad connection between the video cable and motherboard, or the video cable is bad.
The video cable is routed though the left hinge and that’s where the damage may occur.
Remove the hinge cover (as it shown in the service manual) and take a closer look at the video cable. Do you see any damage. Can you make the internal screen work if you move or touch the video cable?
Find out if moving the cable affects video on the internal screen at all.
November 16th, 2009 at 12:27 pm
Dear Barry,
I have the same problem with my HP Pavilion DV9700.
It works perfectly with external monitor and LCD is always black.
Please, if you find some solution share it with me.
Regards,
KomS
November 12th, 2009 at 8:14 pm
I have an HP dv9700z with a display problem. Here are the symptoms. The display remains dark on most boot attempts, but eventually after anywhere beteen 2 and 15 reboot attempts, the screen illuminates and works properly until it is turned off (sometimes for up to 12 hrs). When it is dark there is no image. No HP startup splash screen. As far as I can see, no dim image in the beam of a flashlight (but it is hard to see with the glossy screen in this computer). The computer boots normally whether or not the display works.
An external display works properly and normally whenever it is connected by either VGA, HDMI, or SVideo connector. When connected to an external display and the internal display is not working, the display driver does not see the internal display (only the external display). When connected to an external display and the internal display is working, the driver sees both displays.
When I close the screen when the display is working, the computer goes to sleep normally, and it restarts when the lid is lifted. If the display was working prior to sleeping the computer, the display always works when the computer wakes from sleeping.
Jiggling or jostling the computer does not affect the display. If it is not working, it doesn not blink or start working when bumped…and if it is working, jiggling the computer or moving the display does not cause any changes in behavior (no lines, no blinking, no change in brightness).
I removed and reseated the connectors to the inverter, and no improvement. The computer has never had any foreign material (liquid, dirt, etc.) get into its internals.
So I am baffled. What do you think it might be? To me it sounds like it might be an inverter, except for the absence of a dim image in the dark display…but I may just not know what to be looking for..how dark can the image be?
Thanks in advance for your help…and for all the guidance you have provided me through your advice to others.
Barry
November 3rd, 2009 at 8:49 am
Chip,
It’s good that you were able to fix the problem without replacing parts.
I guess the inverter board had a bad contact with the backlight cable and didn’t provide enough power for the backlight lamp. Let’s see if it fails again.
November 3rd, 2009 at 8:34 am
Kit,
I think you might have two different problems with the laptop.
This description sounds like the inverter or backlight lamp failure.
This part of the description also sounds like the inverter or backlight lamp failure.
Which one is failing? I don’t know. Most likely the inverter board. I would definitely try replacing the inverter first.
Could be bad battery.
I think you should fix the backlight problem first and if it works, move to the battery.
November 3rd, 2009 at 8:26 am
Chip,
The backlight lamp is mounted inside the LCD screen. It’s very hard to replace the lamp because you have to disassemble the LCD. You can try replacing the lamp but only if you have nothing to lose, take a look at this guide: Replacing backlight lamp in a laptop computer. It’s very easy to damage the LCD screen while replacing the lamp.
It’s way easier to replace just the LCD screen. Here’s another guide for you: Replacing LCD screen in HP Pavilion dv6000.
These days new LCD screens are not expensive.
November 1st, 2009 at 1:31 pm
Repair Man:
I commented on my HP DV-6244US earlier where I had a flicker problem that affected one half of my screen. Given I had little to lose, I took the bezel off my LCD, and probed the wires with the laptop on. As a result I found that the lead into the inverter was loose, and upon a bit wiggling, found it fixed the flicker and the screen returned to full brightness. I taped it in place with electrician’s tape and so far, is behaving properly.
October 31st, 2009 at 3:29 pm
Does anybody know the pinout, and specs of this inverter board?
It came out of a toshiba satellite L45, is branded asus and has a part number listed as 08g23fj101c, revision 1.0. It has a 10 pin connector, with an unused pin on the far right.
October 30th, 2009 at 3:46 pm
Hey,
About a week ago my laptop started giving me problems. My screen just went dark and before It went dark it use to have a little flickering. Than recently it just went completely dark, but I noticed that my battery light wasn’t showing up. If I plug it to ac power the light won’t even show that it’s charging. Before the screen went dark for like a month or two I noticed that if I run the laptop on it’s own battery it would say battery too low when it’s been on charge for like two days. I am confused if it’s just the battery that needs to be replaced for the inverter or backlight. How can I know for sure cuz my friend tried to use external monitor on it and nothing showed up on the external screen. Also the computer runs fine I can see that windows opened up and if I look close I see something in the background but the battery light won’t show up either. Hope u can help me to figure out if it’s battery or something else.
October 30th, 2009 at 5:25 am
Repair man:
it was sent on Dec 21 2007, returned Jan 6, 2008. I assume that it is out of warranty, including the repair.
Is the backlight lamp replaceable, or do I need an entire screen for this model?
October 29th, 2009 at 8:07 pm
Chip,
Do you remember what did they replaced last time?
It’s not the inverter or video cable failure.
Sounds like a failing backlight lamp inside the LCD screen. I think you’ll have to replace the screen.
October 29th, 2009 at 4:50 pm
I have a HP DV6244. The screen flickers and dims on the left side only. The right side of the display is bright. The dimming is not black, but more like the display looks when you are running on battery. Fully visible, all the colors, just dimmed. the other half is fine (note that this is half divided vertically from top). Moving the lid sometimes makes the screen go normal, but this is not repeatable. I sent this machine into HP under warranty 2 yrs ago for same issue, and it was fixed then. It has reoccured.
Is this an inverter, cable, or (budget forbid) a backlight/screen?
October 29th, 2009 at 1:36 pm
Ron,
This doesn’t sound like inverter failure.
I think it could be:
1. Loose connection between the video cable and LCD screen/motherboard. Try reseating connections.
2. Bad video cable. Try replacing the cable.
3. Bad LCD screen. Try replacing the screen.
October 28th, 2009 at 5:51 pm
Repair Man
I have an HP ZE5478Cl with the hi res screen. It works sometimes, but will intermittently start flickering, and it looks like a tv with vertical hold problems, white bars flickering. Is that an inverter? it never goes dark. works fine with an external monitor too
thanks