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Dead Pixel Test

Find the dot that never changes colour.

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The screen fills with one flat colour at a time. A dead pixel stays black on every colour; a stuck pixel keeps showing the same colour while the rest of the screen changes.

Clean the screen first. Most suspected dead pixels are dust, and a smudge under a bright white field looks remarkably like a fault.

How to test for dead pixels

  1. 1 Wipe the screen with a dry cloth before you start. Dust and dried droplets are by far the most common cause of a suspected dead pixel.
  2. 2 Start the fullscreen test and step through the colours. Look at the whole surface each time, including the corners, from about an arm's length away.
  3. 3 A pixel that stays black on every colour is dead. One that stays red, green or blue while everything else changes is stuck, which is a different fault and sometimes recovers.
  4. 4 Do this while a new screen can still be returned. Manufacturers set a minimum number of faulty pixels before a panel counts as defective, and the clock starts on the day of purchase.

Frequently asked questions

What is the difference between a dead and a stuck pixel?
A dead pixel receives no power and stays black whatever the screen shows. A stuck pixel is still lit but frozen on one colour. Stuck pixels sometimes free themselves after a while; dead ones do not.
Can a stuck pixel be fixed?
Occasionally. Rapidly cycling colours over the area, or very gentle pressure through a soft cloth, can loosen a stuck subpixel. Neither trick helps a dead pixel, and heavy pressure damages the panel, so stop if nothing happens quickly.
How many faulty pixels count as a defect?
That depends on the manufacturer and the panel class; many allow a handful before a screen qualifies for replacement. Check the policy for your model and keep the receipt, because the return window matters more than the count.
Why does the test go fullscreen?
Because a fault hiding behind the browser toolbar is one you would never find. Fullscreen puts a flat colour on as much of the panel as the browser is allowed to use.

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Webcam Test

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