Hardware Reference
In-Depth Information
Bad Pixels
A so-called bad pixel is one in which the red, green, or blue subpixel cell remains permanently on or
off. Those that are permanently on are often called stuck pixels , whereas those that are permanently
off are called dead pixels . Failures in the on state seem to be more common. In particular, pixels
stuck on are noticeable on a dark background as tiny red, green, or blue dots. Although even one of
these can be distracting, manufacturers vary in their warranty policies regarding how many bad pixels
are required before you can get a replacement display. Some vendors look at both the total number of
bad pixels and their locations. Fortunately, improvements in manufacturing quality make it less and
less likely that you will see LCD screens with bad pixels.
Although there is no standard way to repair bad pixels, a couple of simple fixes might help. One
involves tapping or rubbing on the screen. For example, I have actually repaired stuck pixels on
several occasions by tapping with my index finger on the screen directly over the pixel location (with
the screen powered on). Because I find a constantly lit pixel to be more irritating than one that is
constantly dark, this fix has saved me a lot of aggravation (when it has worked). A similar technique
is to use the tip of a PDA stylus or ballpoint pen to apply pressure or to tap directly on the stuck
pixel. I recommend you wrap a damp cloth over the tip to prevent scratching the screen. Some have
had success by merely rubbing the area where the stuck or dead pixel is located.
Another potential fix involves using software to rapidly cycle the stuck pixel (as well as some
adjacent ones), which sometimes causes the stuck pixel to become unstuck and function properly. The
two main programs for doing this are Udpixel ( http://udpix.free.fr ) and Jscreenfix
( www.jscreenfix.com ) .
Unfortunately, none of these fixes work all the time; in fact, in most cases the pixel remains stuck on
or dead no matter what you try. If you have stuck or dead pixels that do not respond to any of the fixes
I've detailed, you might want to contact the screen or laptop manufacturer to inquire about its bad
pixel replacement policy. Because the policies can vary widely among different manufacturers and
displays, to find the allowable defect limits for your specific display, I recommend you consult the
documentation or contact the manufacturer directly.
Troubleshooting Monitors
Follow the suggestions in the following sections to help fix problems with your display.
No picture
Solution
If the LED on the front of the monitor is yellow or flashing green, the monitor is in power-saving
mode. Move the mouse or press Alt+Tab on the keyboard and wait up to 1 minute to wake the system
if it is turned on.
If the LED on the front of the monitor is green, the monitor is in normal mode (receiving a signal), but
the brightness and contrast are set incorrectly; adjust them.
If no lights are lit on the monitor, check the power and power switch. Check the surge protector or
power director to ensure that power is going to the monitor. Replace the power cord with a known-
working spare if necessary. Retest. Replace the monitor with a known-working spare to ensure that
the monitor is the problem.
Check data cables at the monitor and video card end. Check power cables to the video card if the
 
 
 
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