Laptop LCD goes black

[avatar_58]

This is something for my work, which has been happening a little too much.

The screens of many laptops will just go black for no reason. The picture is visibly still there...but practicaly just black (faint outlines). On a few laptops we have replaced the entire LCD and they work fine now. However, I'm still wondering if this was the cause.

A new laptop just recently has this problem. When the harddrive was switched with another laptop, both worked fine and when left for hours they did not go black. We then put the original HD back in, and amazingly all was fine. However...not 10 mintues after returning it to the worker it went black and she called us (IT).

Ack...given this info I would assume it was the power supply....yet why have the replaced screens not gone dark since? http://forums.3drealms.com/ubbthreads/images/graemlins/confused.gif We're probably going to just replace this LCD as well but I just don't understand this...even Dell can't answer it (surprise, surprise) http://forums.3drealms.com/ubbthreads/images/graemlins/wink.gif

In case you needed to know they all have XP SP2 and latest drivers. Upon searching on google I found that it is not hardware dependant and can happen on other laptop types...very odd....

[Kevin Wolff]

The picture is visibly still there...but practicaly just black (faint outlines).


Sounds like a bad backlight. I wonder if this got replaced along with the LCD.

[NutWrench]

Is it recoverable? i.e. if you move the mouse/bang on the keyboard does the normal screen come back?

Does it happen after a period of inactivity (i.e. maybe some power-saving thingy is involved)?

[Wamplet]

avatar_58 said:
...even Dell can't answer it (surprise, surprise) http://forums.3drealms.com/ubbthreads/images/graemlins/wink.gif




Stop right there:

http://forums.3drealms.com/ubbthreads/images/graemlins/mryuck.gif

What Kevin said as well. If the screen is still visibile, but it's darker than hell, it's the backlight. Depending on the manufacturer, it may require the entire LCD screen section to be replaced.

[avatar_58]

Ok, but if its the backlight then why the hell does swapping harddrives fix it? http://forums.3drealms.com/ubbthreads/images/graemlins/confused.gif That makes little sense. I really want to know whats doing this.....and no its not recoverable until you power off and on. I came across a site saying it was the LCD inverter being faulty and replacing the screen did fix the others. However why did swapping HDs fix it?? http://forums.3drealms.com/ubbthreads/images/graemlins/doh.gif Something isn't right here....

[NutWrench]

Does the LCD screen go black after the computer has been inactive for a while?

I still think it's some kind of power-saving setting. Some brands of hard drives and monitors don't recognize the Windows "wake up" signal. What happens if you change the Power Scheme to 'always on?'

[Spyd]

It's the backlighting. LCDs have one or two flat flourescent lights to lit the pixels behind the actual LCD panel. Usually they are replaceable. And you know that flourescent lights act strange when they're about to die.
But there's another thing: in laptop computers, the switch that detects that the screen is closed has two uses, connects to the "suspend" pin on the motherboard, and powers off the backlighting in the LCD to cut power usage while the screen can't be used.
It can be that this switch is stuck or not working well, so that's why a simple HDD change (that makes you move the laptop up and down) can "unstuck" the button and work well for a while.

So:
-If the backlighting is dead, check the manufacturer if they can fix/replace the backlighting. If they want to change the whole screen, think before doing it... sometimes is better (price wise) to buy a whole new laptop.
-If the switch has dirt or any other thing, just clean it. But if the switch is dead, the fix will cost too much: new laptop, too.