Backlight or inverter problem?

[T41Tablet]

After changing the system board on my X41 Tablet, it seemed the LCD has gone. I checked all the connections to the board several times but with no joy.

I have been using the lappy on the VGA out which works fine, I noticed today that there is a very faint picture on the screen. It is extremely dark and turning up the brightness does nothing.

After some reseaching on the internet I am not sure if the CCFL light is broken or the inverter is. Or are these the same things?

I opened up the LCD bezel and got a FRU for the inverter 39T0423 found some cheap ones on ebay ~15 bucks a go. A replacement LCD is about nearly 10 times as much and it is used.

Anybody have any ideas?

I am cursed with hardware failure on this tablet over the last two weeks...

[rkawakami]

CCFL (aka, backlight) is the lamp that's inside the LCD panel. The inverter is the board/circuit which provides the required power to light up the CCFL. There are several things which go into lighting up the CCFL:

- lid switch (which, at the moment, I have no idea where it is on the X41t could it be built into the hinge??)
- motherboard power supply
- LCD ribbon cable; it carries the relatively small DC voltage to the inverter
- the inverter; it changes the small DC voltage into a large AC voltage
- the CCFL
- and any connections between these various pieces

The easiest things to replace are the inverter and LCD ribbon cable (usually). If those things don't fix the missing light, then that typically points to the CCFL being the problem. A smaller, but still possible chance, is that something on the motherboard has died. That can be something as simple as a fuse, or major, like a power controller IC.

[epr02]

I am having the same issue, but on a T20. The thing is that vga works (like yours) fine but the LCD has a faint picture, but by chance one day I jarred it and the LCD came on. After that I learned to tap lightly one corner of the rear of the laptop on the table and it would come on. You might want to see if that works for you on lighting up your LCD. I would think that if it does light up like mine does that that would narrow down the issue of your LCD.

Don't mean to hijack your thread but would anyone off-hand know what this might be?

[rkawakami]

- and any connections between these various pieces

I'd say that there's something loose in the chain of components I mentioned. Intermittent switch, LCD ribbon cable not plugged all of the way in, a small tear or crack in said cable, loose connection of the inverter board to the cable, bad connection of the backlight's connector to the inverter or the hardest thing to pin down, a loose component on the motherboard. Really hard to say which it might be without being able to poke around at those various parts/places. If you do this on a live system, be very careful around the inverter; it can provide quite an electrical shock.

[T41Tablet]

I found this, hopefully according to the symptoms it is the inverter that is kaput

http://www.laptoprepair101.com/laptop/2 ... backlight/

[epr02]

Good find thanks...

[shinjiplus]

my X41 screen also has no backlight... but the status LEDs also don't work!

originally the backlight went out and some of the status LEDs, so i tried replacing the inverter and that actually caused the rest of the status LEDs to go out.

would a new LCD ribbon cable fix this?