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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July 25th, 2009 at 9:17 pm
Mike,
Can you boot in Safe mode? When Dell logo appears on the screen, press F8 and select Safe Mode. Will it boot this way?
July 25th, 2009 at 8:42 pm
htnakirs,
That’s right. If the screen lights up there is nothing wrong with the inverter board.
Test the laptop with an external monitor. Can you get video on the external monitor?
If you get the same bad image on both screens, there is a problem with the motherboard. Test your laptop with an external monitor first.
July 25th, 2009 at 10:28 am
I have a Dell Vostro 1400.
The display is just black. It does not work with a external monitor, the same results black screen.
I can see the Dell logo when the laptop first boots. I can run the diagnostics, which detects no problems the video test is fine as well. I can see all the patterns. I can go into the Bios without any problems. After the Dell logo comes up when I first boot the computer it goes black. No beeps or anything. Could this be a inverter or back light problem?
Thanks
July 23rd, 2009 at 3:26 am
I have an Acer 4710z.
The display shows only lines and a pale gray colour, no image. The inverter is working fine, since with the signal cable unplugged the screen lights up white. On plugging the signal cable the lines return. I am not sure if it is the cable or the LCD to blame.
Any idea?
July 16th, 2009 at 9:06 pm
William,
First of all test you laptop with an external monitor. Do you see same problem on the external monitor when the laptop display is open all the way? If you do, there could be a problem with the video card.
If the problem appears only on the laptop screen and external video is fine, most likely it’s either cable related problem or bad LCD. You can try reconnecting the cable.
July 11th, 2009 at 8:11 pm
Hey Repair Man,
When I open my DV9740US HP Pavillion all the way, the black areas become red and dotty, but when I pull the screen towards me (to about where its 70 degrees open) – the screen goes back to normal. Does this sound like a loose connection, or some bigger hardware issue? Not having any other noticeable problems. I’m a little nervous about making the repair, but don’t have any other options (no $$$ and I’m a college student).
July 10th, 2009 at 10:39 am
Victoras,
Did your broken screen light up at all?
If it did, try connecting the broken screen again. If the broken screen still lights up but the new one doesn’t, it’s possible there is a problem with the new screen.
July 10th, 2009 at 9:26 am
Hello, i have same problem. Change broken screen, tried on external screen, works fine,tried another inverter, same dark screen,tried another screen, same dark screen. Maybe You resolve this problem?
Thanks for your help
Viktoras
Bobby Says:
June 7th, 2009 at 11:49 pm
Hi.
I’ve changed a broken screen on an HP Pavilion dv5000, first start worked really fine, all light and brite, put all together again and now almost no light, just very dark.
tried on external screen, works fine.
tried another inverter, same dark screen
tried another screen, same dark screen
took some more apart and checked the screen cable were seated at board, same dark screen.
Now I’m out of ideas!!
Thanks for your help
Bobby
June 19th, 2009 at 12:08 pm
pam,
Looks like the power gets to to inverter and the voltage is about right. You cannot test voltage on the other end with a multimeter.
It’s possible but not very likely.
I think you have a problem with the backlight lamp inside the LCD screen. You can test the backlight using the method I linked to in the comment 107.
June 19th, 2009 at 11:35 am
Hello. My wife stored a bottle of water with her laptop in the carring case. Unbeknownst to her, the cap had fallen of the water bottle and the laptop had been sitting in about a 1/4″ of water for about an hour. The laptop was in standby and the backside (where the screen connects to the laptop) was the only part of the computer immersed in the water.
After letting it dry thoroughly, we tested the computer. The laptop turns on and works fine with an external monitor. However, the screen remains extremely dark all the time with only a very dim image outline (can be seen with a flashlight). Do you think it is the inverter, backlight, or both. Thank you for any help you can provide.
June 18th, 2009 at 6:00 am
Hi.I have a toshiba laptop EL10-142 working fine except there is no backlight.It works on a external monitor when first turned on but then it returns to the dark laptop screen.I have bought two replacement inverters from ebay but still no joy.When i test them with a multimeter they all have 14.75 dc volts going in at the top pin one end but no ac at the other.I used the laptop as an earth and probed both pins inside.I also probed both pins at the same time as i am not sure of the correct way to test ac current.Should there be power at the backlight end? if so do you think that both replacements could be faulty? Please help.Thanks Pam.
June 11th, 2009 at 5:39 am
Hello, I am actually having the exact same problems as Bobby. What could this be? I replaced the screen and on the first couple starts, it worked perfectly normal. Everything wasn’t put back together so I finished up the install, and all of a sudden its just very dark. External monitor works normal. Any thoughts on our problems? Could it be the video cable or the motherboard?
June 7th, 2009 at 11:49 pm
Hi.
I’ve changed a broken screen on an HP Pavilion dv5000, first start worked really fine, all light and brite, put all together again and now almost no light, just very dark.
tried on external screen, works fine.
tried another inverter, same dark screen
tried another screen, same dark screen
took some more apart and checked the screen cable were seated at board, same dark screen.
Now I’m out of ideas!!
Thanks for your help
Bobby
June 7th, 2009 at 5:46 pm
John,
It’s hard to tell which one is failing. It’s either bad inverter or backlight. Both parts have very similar failure symptoms. In order to find out which one is causing the problem you’ll have to replace the inverter board or test the laptop with a known good backlight lamp.
Now that sounds more like the backlight lamp failure.
June 7th, 2009 at 5:12 pm
Hi,
I have a Toshiba Satellite M105 S3004 laptop with a 14 inch LCD Display. The screen in my laptop is very dark but i can see the images still being there. However, if i put the screen down for standby and open it back up, the screen becomes brightes for a few seconds and gets dark again. Is this a problem with the backlight or the inverter or any other component.
Additionally, when it does light up, the right side of the screen is brighter than the left side. Is this all becasue of the same problem? Will really appreciate your help.
June 7th, 2009 at 11:10 am
Kevin S,
It’s not related to the inverter board, that’s for sure. The LCD screen is still bright and you can see the image, so the inverter works properly.
Something is wrong with the LCD screen.
June 7th, 2009 at 10:58 am
Hi
I have a problem with an lcd screen on a laptop.
The screen has paler areas arond the bottom edge and right hand side but the picture is all there, just paler.
Do you think this is an inverter problem or is the screen on it’s way out?
June 6th, 2009 at 12:24 pm
Chris,
The LCD lights up so it’s not the inverter. The external monitor works fine so the video card and motherboard work properly.
I think it’s either bad LCD cable or bad video cable.
June 6th, 2009 at 11:36 am
Franco,
Did you replace just the LCD screen or the new screen came with the inverter board?
Have you tried connecting the old (broken) screen back to the laptop and test if it lights up properly from the AC adapter and battery?
June 6th, 2009 at 11:17 am
John V,
Which one? No backlight?
If you get a garbled image on the external monitor, most likely your problem is related to the video card. The screen inverter board cannot affect image on the external monitor at all.
Again, if you are talking about the image on the external monitor, it sounds like a problem with the video card.
Do you know that HP fixes some out-of-warranty dv2000/dv6000/dv9000 notebooks at no charge? Here’s more information about HP warranty extension program. Maybe your dv6000 qualifies for that repair.