Vanjul Bhatt

Estimable
Feb 3, 2015
2
0
4,510
I shutdown the laptop yesterday night. Tried to switch it on in the morning but the LCD display won't come on. The Windows boots up , the fan rolls , the DVD drive shows activity , i can hear sound of windows booting up but no display on screen.

On looking through the forums i came upon some tests to isolate the problem.

I tried:

1. The LCD BIST(Built in self test) : Passes. All colors are displayed with no distortion of any kind. Crystal Clear display.

2. Connect Laptop to an External Display : Pass. I connected to a VGA Monitor. The Display comes on . I am typing this post using the external display infact.

3. The Laptop is getting past POST so no residual charge problem.

As both these tests have been passed by the laptop . I don't know what the problem is. Is it the Cable or something else? Please Guide.

Thanks in advance.

Vanjul.
 

BeADev

Estimable
Nov 2, 2014
10
0
4,570
normaly means dead back light. try turning it on and shining a bright light into the screen if theres an image there the backligt is gone.

if not then its likely the connector between the screen and the motherboard. they tend to break at the bazel.
 

Vanjul Bhatt

Estimable
Feb 3, 2015
2
0
4,510
Hi,

Thank you for the prompt reply. One thing i would add is that i found the display was not blank but VERY dim such that it was almost invisible.

I checked with a local technician. He changed the display cable but the laptop screen still had a very dim display.
He changed the LCD screen to check if backlight is gone but it had a dim display on his test LCD screen too.

The remaining culprit was the motherboard. I made him check it and found that some transistor responsible for brightness control has gone bad. He replaced it and Voila!

The display is back to normal. Thanks for the help. Very much appreciated.

Vanjul.