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.
Need spare parts for your laptop?
If you are looking for spare parts for your laptop you can find brand new and used parts here. Just search by the part name and laptop model.
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
October 27th, 2009 at 8:23 am
Jodi,
Most likely it’s either bad inverter or backlight lamp failure.
I would suggest replacing it with the exact replacement part. I cannot tell if your new inverter works properly or not.
It’s likely that there is nothing wrong with the inverter board. Usually the screen looks pinkish when it has a faulty backlight lamp.
When the backlight fails, you have to replace the LCD screen. It’s very hard to replace the backlight lamp inside the screen though possible.
Take a look at this post. It explains how to test the inverter board without buying the entire LCD screen (you still have to buy a new backlight for test).
Again, you mentioned the pinkish screen and I think it’s related to the backlight lamp failure.
October 24th, 2009 at 12:21 pm
My Dell Inspiron E1505 laptop has been having a display problem: the screen is dark with barely visible images but it works fine with an external monitor. I commented about it on this site a few weeks ago and determined that my inverter needed replacing. I bought a replacement inverter online (not a genuine Dell part). It didn’t look exactly like the one in the latop, but it fit. Once it was installed, the display worked again. Yea! But after about 20 minutes, I noticed the screen looked pinkish: this had happened the first time the display failed. Then, without warning the screen went black and that was it. It functioned for maybe 1 hour befor ethis happended. The symptoms are the same as the first time: I can faintly see images on the display but the screen is not backlit. Is my laptop burning out inverters for some reason? Is there a remedy? Could it be because I didn’t use the precise Dell replacement part?
October 13th, 2009 at 8:04 pm
Nikki,
What does it mean? How can you fix the screw by moving the monitor. It’s not clear.
I cannot tell what is wrong without looking at the laptop.
Could be bad connection between the video cable and inverter. Reseating the cable connection may help.
October 13th, 2009 at 7:59 pm
Ed,
Can you see any damage made by spilled coffee on the video cable?
If not, I really doubt that a new cable will make any difference.
If a new LCD lamp and inverters didn’t help to light up the LCD, most likely you have a problem with the motherboard.
October 12th, 2009 at 10:49 am
Repair Man, re: my M1210 w/ the coffee spill, I bought a new LCD lamp to test with per your recommendation. But, no diff connecting to 2 different inverters. Any final suggestions to try, like the LCD cable perhaps?
If not, I’ll decide to either replace the mobo or just try to use with an external monitor going forward.
Thanks again,