21.5" Samsung LED screen bottom 3/4 is grey while the upper 1/4 is fine

[dashperado]

It started when screen had a fade color line for weeks. Then just now the lower portion of the fade color line went grey and the upper portion is fine. I tried removing and inserting again socket from the panel to the main board but it still persists. Not a desktop graphics issue since I connected another monitor and works fine.

Here is the image:

What could be the problem here?

 

[vrumor]

Your monitor. Replace it. Youve already hooked up another one and it worked fine.

 

[dashperado]

It started when screen had a fade color line for weeks. Then just now the lower portion of the fade color line went grey and the upper portion is fine. I tried removing and inserting again socket from the panel to the main board but it still persists. Not a desktop graphics issue since I connected another monitor and works fine.

Here is the image:

What could be the problem here?

Your monitor. Replace it. Youve already hooked up another one and it worked fine.

Hi, thanks, but I am trying to get a more specific answer other than the monitor itself, obviously.

 

[vrumor]

If the monitor is broken, what more specific answer do you want?

 

[dashperado]

If the monitor is broken, what more specific answer do you want?

Well, what comprises a monitor that is. If what causes the problem is a single component, maybe the panel, the mainboard, or a single chip in the mainboard, I would have a better decision on what to do next than replacing the whole monitor.

 

[vrumor]

Any attempt to repair it, unless you do it yourself, will cost more than its worth. And depending on how you value your own time, its most likely not worth it. It would be hard to pinpoint exactly what it is without someone with knowledge looking at it. Anything else would just be an assumption really.

 

[dashperado]

Any attempt to repair it, unless you do it yourself, will cost more than its worth. And depending on how you value your own time, its most likely not worth it. It would be hard to pinpoint exactly what it is without someone with knowledge looking at it. Anything else would just be an assumption really.

Thanks. Surely, some people here had experience this and or probably were able exactly pinpoint the cause and fix it without resorting to buying a new one. I am hoping for them to notice me.

 

[Solandri]

Short answer: Buy a new monitor or exchange this one under warranty.

Long answer: The LCD panel has a bunch of waveguides and diffusers which take LED lights along the edges of your monitor, and spreads the light evenly (more or less) across the entire screen. The LCD itself sits on top of all this, and selectively blocks or lets through the light on a pixel-by-pixel basis. There's also a mask in between the individual pixels which helps block light leaking out in between the pixels.

Looking at your picture, I can think of three possible causes:

• 
  ■The waveguide/diffuser have become separated and are shining excess light into the bottom portion of your screen.
  ■The mask which blocks light from leaking out in between pixels has detached or somehow failed.
  ■Or the LCD rows in the bottom portion of your panel are not getting the correct signal, so are displaying grey instead of black.

The first two are not user serviceable. In theory you could take apart the panel and insert replacement parts. In practice, even if you're able to pull it off without destroying the different layers, the monitor is likely to look worse after your "repair" because these parts need to be aligned precisely in a clean room. Otherwise you get uneven brightness, and smudges due to dust or bugs being trapped in between the layers.

The third one *might* be fixable by the end user, but still involves a lot of labor which could easily end up destroying the monitor. The monitor takes the signal from the video card, and sends signals to two edges of the screen to address the rows and columns of the LCD. The electrical interface from these copper signal lines to the panel itself (often a conducting pad) sometimes comes loose resulting in the poor or no signal transmission. You can sometimes fix it by massaging the panel right where this interface is.

But I've only gotten this to work when a couple lines have flaked out. Nothing as big as 80% of the display surface. The large area of failure suggests some common cause of the failure (maybe some water spilled inside the monitor, reached these contacts about 20% down from the top of the panel, and ran down the entire edge compromising the signal lines from that point down). It'll just be easier/cheaper to replace the monitor than to try to fix it.

 

[dashperado]

Short answer: Buy a new monitor or exchange this one under warranty.

Long answer: The LCD panel has a bunch of waveguides and diffusers which take LED lights along the edges of your monitor, and spreads the light evenly (more or less) across the entire screen. The LCD itself sits on top of all this, and selectively blocks or lets through the light on a pixel-by-pixel basis. There's also a mask in between the individual pixels which helps block light leaking out in between the pixels.

Looking at your picture, I can think of three possible causes:

• 
  ■The waveguide/diffuser have become separated and are shining excess light into the bottom portion of your screen.
  ■The mask which blocks light from leaking out in between pixels has detached or somehow failed.
  ■Or the LCD rows in the bottom portion of your panel are not getting the correct signal, so are displaying grey instead of black.

The first two are not user serviceable. In theory you could take apart the panel and insert replacement parts. In practice, even if you're able to pull it off without destroying the different layers, the monitor is likely to look worse after your "repair" because these parts need to be aligned precisely in a clean room. Otherwise you get uneven brightness, and smudges due to dust or bugs being trapped in between the layers.

The third one *might* be fixable by the end user, but still involves a lot of labor which could easily end up destroying the monitor. The monitor takes the signal from the video card, and sends signals to two edges of the screen to address the rows and columns of the LCD. The electrical interface from these copper signal lines to the panel itself (often a conducting pad) sometimes comes loose resulting in the poor or no signal transmission. You can sometimes fix it by massaging the panel right where this interface is.

But I've only gotten this to work when a couple lines have flaked out. Nothing as big as 80% of the display surface. The large area of failure suggests some common cause of the failure (maybe some water spilled inside the monitor, reached these contacts about 20% down from the top of the panel, and ran down the entire edge compromising the signal lines from that point down). It'll just be easier/cheaper to replace the monitor than to try to fix it.

Thanks, I am getting a second-hand monitor with exact same model for a little less than 50% the original price to switch some parts and know what is truly causing the trouble (I've torn it down and able to assemble it back out of curiousity, but not as clean as before, I think.) Appreciate the thorough info

EDIT: I have concluded the LCD panel LTM215HT05 as the culprit. Tested it using an identical model and that confirms the 3rd bullet you pointed out.