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I just bought a full HD Acer LED monitor (21.5'') and noticed that there was a red dot on the right hand side - sort of like a dead pixel. After a few days, this dot disappeared. A few days later, and now it's back. It only appears on a coloured background, i.e. does not show over white.

What exactly is this, I'm guessing it's not a dead pixel since it disappeared and is now back? Is there anything I can do to fix this?

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It sounds like it is indeed a defective pixel. More specifically, a "stuck" pixel. – iglvzx Jun 26 '12 at 0:25
Likely a stuck-on red pixel. It won't be visible if the section of the screen is displaying any sort of background, but will stick out like a sore thumb if the background is solid black. – Daniel R Hicks Jun 26 '12 at 1:23
up vote 3 down vote accepted

Sounds like a defective pixel. All pixels are made up of sub-pixel color arrays, one for red, one green, one blue. Maybe in this case the red one is stuck as on? Then when the other two come on, you get white.

You could test this buy using a straight green or blue image over that area of the screen, and look for variations.

I'd suggest exchanging it before your return policy runs out.

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So is there nothing I can do myself? As the shop informed me that I must have atleast 5 to return it :/ – Help Jun 26 '12 at 11:26
I think that's bad policy. Often, if you complain loud enough, they'll do something. I would find that reaction unacceptable, myself; especially smaller places need to stand behind what they sell to retain the following they have built. I do not recommend doing something like this on a new monitor, but here is a site showing a method to try yourself (warrany voiding, I'm sure). – serotonin Jun 26 '12 at 16:45
Thats very strange - i just tapped the pixel on the screen with my finger and it disappeared. – Help Jun 26 '12 at 18:56
Glad to hear! Still, I'd imagine that this process has resulted in a few cracked screens. I learned something new to try (albeit on older out-of-warranty monitors) – serotonin Jun 26 '12 at 20:12

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