Display very dim, barely visible under torch light

[kaZep]

Hello everyone,

So recently my laptop HP Pavillon G7 1240sf has started to act really weird, sometimes the display was getting very dim then going back to bright. But it seems that now it has completely stopped working and it went full dim. No visible to naked eye, i tried to turn on my phone torch and stick it to the pixels, surprisingly it worked. I tried to make BIOS modifications through another screen connected to the computer. The brightness is to maximum, same for the OS, i tried turning the brightness to max. it is already pushed to limits.

What i do not understand is how comes I can see the image when i brighten the pixels with a phone torch. Is the lamp inside the screen (if there's any) broken? Or are the pixels barely dead but still capable of creating very dim colors?

Thanks in advance.

 

[Solandri]

Yes, that's what happens when the backlight (lamp) or the fuse for the backlight dies. According to that model's specs, it uses a LED backlight. It's rarer for those to die (CCFLs typically died after 5-7 years), but they can die.

Unfortunately, this isn't something a typical end user can fix by themselves. The fuse is not user serviceable without specialized equipment. And although in theory just the LED lighting strips can be replaced, in practice they're usually sealed withing the screen and it's easier to just replace the entire screen. You'll have to talk to a local repair shop, or just hook it up to an external monitor and use it as if it were a desktop.

 

[DeadlyDays]

How an lcd monitor works.
the pixel is the lcd essentially, they twist or something when electricity passes through or what not and let more or less light through(different spectrums maybe), somehow there is color involved and stuff. In front of this lcd panel is a glass plate essentially so your smudgy fingers don't touch the lcd panel directly. Behind the lcd panel is a bunch of "diffusion" sheets which help spread the light out(I don't remember if there is a glass plate back here somewhere). Basically foggy paper. There is also this like magnifying sheet which is kewl and also does something to spread the light out. then you have a white backing to reflect light better n stuff. Then somewhere you have a backlight to shine light through the lcd's which twist and stuff to give you colors.

So old lcd panels use ccfl bulbs along an edge, or multiple edges like top and bottom. Typically soldered in. For newer ones, you have LED LCD's that user LED strips instead to provide backlighting. Solandri's answer goes into that.

if the backlight is out, you can prove this because you can shine a bright light into the monitor, you see the light passing back through to you after reflecting off the white background(diffused from the sheets of course) and can make out what is happening because the LCD's are still working.

So the LCD's don't actually generate light(unlike plasma screen where it does, pass electricity through the stuff in the plasma pixel and it lights up pretty)

 

[kaZep]

Any ideas about what can do?