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Laptop Screen Inverter

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February 22, 2009 6:33:42 AM

Before i even post my question, knowning this is not general knowledge, does anyone knows what a screen inverter is? From a laptop lcd!

I need some medium\expert knowledge on this as i am having a problem with a screen inverter and the backlight of the lcd won't even turn on...has anyone ever had the need to replace one and knows what i am talking about?

Many thanks in advance.

More about : laptop screen inverter

February 22, 2009 10:26:23 AM

nah no one knows. screen inverters they play with the voltage to give backlight support to your lcd's bulb
they're sensetive and they do fail time to time. replacing them is easy but finding the correct one is hard as it must come from the same laptop model
February 22, 2009 12:46:15 PM

My problem is, the laptop was faulty, the cable connecting the laptop and the screen inverter was in bad shape, and the screen would only light if the screen was open to a certain angle, then i just barely took the cap over the wire to watch it, and the whole four wires inside shortout, and now the backlight wont light up, so im guessing that either the screen inverter or the motherboard went bad.
I readed the input voltages with a voltimeter, and acording with this site http://www.lcdinverter.co.uk/env032.htm only pin 3 wont read right, it should be 5 volts, and it reads only 0.01v, so im guessing that its a motherboard problem.
Im thinking about connecting just for a tryout the 5 volts that juice the hdd (without the hdd itself) just to test if its really the screens inverter fault or the motherboard itself. What do you think?
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February 22, 2009 1:27:47 PM

it can't be the board, have you replaced the inverter with a new one? 99% of the time this fixes it if there;s no 5 volt coming from the (pink and white cables connector) then its the inverter needs changing, if you do change the inverter and its the same problem then its the LCD bulb in the screen that's gone! which is difficult to change
February 22, 2009 4:38:45 PM

But judging by the scheme i showed you the 5 volts where input, not output, then the pink and white cable you mentioned are the output that juice the bulb.

Why you say it can be the board, when the wires where in such bad shape that they where shorted, GND with the 19v and 5 v etc, something on the board may have gone wrong with that :( 

But say more about what you think, i need opinions since this isnt even my laptop, its my girlfriends laptop so im in a trouble :D 
February 22, 2009 7:06:17 PM

have you tried another screen? just use any other laptop screen same size as long as it has the same pins which is normaly (30 pin connector)


did you say when you bend the screen it comes?then it means it's the cable that connects the screen with the base. it's very rare for a motherboard not to ship voltage to the inverter even if its shorts, it normaly dies to protect itself and even if it's shorting now it won't let you power the laptop at all.

you can't realy tell unless you have the following.
a new inverter from ebay, a additional test screen

to find if the board is shipping 5v you can't find that out from the inverter, you have to find it from the (4pin connector without the inverter being connected to) if there's no voltage there (whilst the laptop is with the AC on) then it means the cable has a cut, also sometimes it's where the cable is connected on the board take it off and see if there's any pins that are bent!! use a needle to correct them.

in the last 5 years of my career i only had 1 case where no matter what i did there was no backlight! that's 1 out of 5000 laptops looked at..
February 22, 2009 8:17:55 PM

Well, make that two, because there where no bent pins, and the 5v wire only measured 0.01v, so i did as follows: i connected the ps2 5v to the missing 5v input of the screen inverter, and guess what, the screen worked, which means that the screen inverter is fine, and something went wrong on the motherboard.
So now i need to check for some burned SMD components on the motherboard! I was so happy that i found that before i bought a new inverter...

Thanks for your help, its good that someone here knows what im talking about, because this is also PC hardware, just not the most common average joe pc hardware.

February 22, 2009 8:55:25 PM

yeah well, that laptop I remember there were more than 5 capacitors gone and at the time I didn't have (hot soldering tool) to change them + it was an old one and not worth spending time on it. but it looks like you know what you're doing so find a good motherboard manual for your laptop which I usualy email the manufacturer and they email me back a page..

otherwise spend few hours with the volt meter checking all the cmds, i hate doing that lol but a hot air tool is realy realy nice to use when it comes to laptop boards or else a controlled electric solder I think the temp to desolder is about 320 and to solder is around 270.

good luck! and this questions can't be answered by the other guys here except if you ask for example (how to use facebook and myspace lol) but there's this guy frozenland he knows some good stuff too.
February 18, 2013 5:36:55 PM

rickzor said:
Well, make that two...



LOL!
a c 249 D Laptop
February 18, 2013 5:41:32 PM

cheaptofix said:
yeah well, that laptop I remember there were more than 5 capacitors gone and at the time I didn't have (hot soldering tool) to change them + it was an old one and not worth spending time on it. but it looks like you know what you're doing so find a good motherboard manual for your laptop which I usualy email the manufacturer and they email me back a page..

otherwise spend few hours with the volt meter checking all the cmds, i hate doing that lol but a hot air tool is realy realy nice to use when it comes to laptop boards or else a controlled electric solder I think the temp to desolder is about 320 and to solder is around 270.

good luck! and this questions can't be answered by the other guys here except if you ask for example (how to use facebook and myspace lol) but there's this guy frozenland he knows some good stuff too.


Hi :) 

Please do not run down guys you know nothing about :( 

There are a LOT of experienced Laptop repair techs here to help....as an example, I own a Laptop repair company...

And its against Toms rules to insult other users....

All the best Brett :) 
February 18, 2013 6:23:58 PM

There are fuses before the video out plug on the motherboard too. Not sur if the 5v line has one though.
!