Laptop Screen top part working bottom part all white

[dicky96]

Hi guys, I have an old laptop here I'm just trying to fix for the fun of it really

The top part, maybe 25% or 33% of the screen display works, (DOS boot text or bios screen, I have no HDD fitted) but the bottom part is all white.

On an external monitor connected to the VGA the picture is good.

So basically I have a horizontal division, below which the screen is all white. There is no apparent damage to the screen or any vertical lines

I tried cleaning the pins on the LVDS connector plug/socket as thy looked a bit dirty (18 pins plus ground) but it did not help

On the screen TCON board is an eprom S-24CS02A which I assume is the EDID data or something like that. This is compatible with my TL866 programmer so I could remove it and read/write to it if I want to.

Is this type of fault possibly caused by a corrupted eprom or other problem on the TCON board or is it always a faulty LCD panel itself?

If it is eprom, where can I find a suitable file to write?

See pics for all the numbers marked on the LCD panel. Airis LM13W

best regards
Richard

[mon2]

Re: Laptop Screen top part working bottom part all white

Post a picture of the actual display in action while it is not working as described.

[piernov]

Re: Laptop Screen top part working bottom part all white

Probably column drivers not receiving the bias voltages due to a break somewhere. Comparing the voltages on the test pads on the column driver tab that works with the ones that don't may help figuring out the problem. Then it's possible to jump the missing rail, assuming that's the only problem. Even if that fixes it, the panel cannot be considered reliable anymore.

[dicky96]

Re: Laptop Screen top part working bottom part all white

@mon2
I can do that tomorrow. The bottom 3/4 or 2/3 are just plain white when viewed directly straight on and have some greyish lines in them when viewed at a wide angle. The top area looks perfect all the way across the screen when in the BIOS or on DOS load screen - I don't have HDD attached. There is a sudden point below it goes from a good picture to all white, like for example if someone had placed a piece of white A4 paper over the bottom portion of the screen - just like in this image (not mine, and mine is like 1/4 OK and 3/4 white, not half and half)

https://ccm.net/forum/affich-963190-...creen-is-white

@piernov where is the 'column driver tab'? Wouldn't a problem with column driver cause vertical lines or vertical area of the screen to not work? Just based on the fact that columns (in architecture at least ) tend to be tall vertical things

[piernov]

Re: Laptop Screen top part working bottom part all white

Yes my bad, I meant row drivers. Panel need to be partially disassembled as the tabs are behind the metal frame, on the side of the panel. (some panels don't have them at all, may be driven directly from the row drivers, not sure)
The column drivers would cause vertical bands instead, they are on top between the PCB and the actual LCD, seen in your last picture. Row drivers look the same but there's only one side connected.

[SMDFlea]

Re: Laptop Screen top part working bottom part all white

If it is eprom, where can I find a suitable file to write?

here https://www.badcaps.net/forum/showpo...6&postcount=81

Airis LM13W

The motherboard is made by FIC ,here`s a schematic in case you run into some other problems

https://www.badcaps.net/forum/showpo...62&postcount=1

[dicky96]

Re: Laptop Screen top part working bottom part all white

Due to some misadventure I no longer have the eprom chip and Aliexpress don't appear to have S24CS02A

Is there some equivalent I could use?

[mon2]

Re: Laptop Screen top part working bottom part all white

Use the Atmel AT24C02 here. The original is nothing special...just a standard I2C bus 5 volt eeprom.