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Troubleshooting Video Capture Devices 259
adapter, so don’t dismiss a monitor that shows those lines
without using another adapter to double-check the effect.
• A good monitor will be calibrated so that rays of red, green,
and blue light hit their targets (individual phosphor dots)
precisely. If they don’t, you have bad convergence. This is
apparent when edges of lines appear to illuminate with a
specific color. If you have good convergence, the colors will
be crisp, clear, and true, provided there isn’t a predominant
tint in the phosphor.
• If the monitor has built-in diagnostics (a recommended feature),
try them as well to test the display independent of the
graphics card and system to which it’s attached.
Use Table 10.25 to troubleshoot specified problems.
Table 10.25 Troubleshooting Display Problems
Symptom Cause Solution
No Picture LED indicates power- Move the mouse or press Alt+Tab on
saving mode (flashing the keyboard and wait up to one
green or yellow by minute to wake up the system if the
power switch). system is turned on.
LED indicates Check monitor and video data
normal mode. cables; replace with known, working
spare.
Turn off monitor; reset mode switch
to correct setting (analog for VGA).
Check brightness and contrast control;
adjust as necessary.
No picture; no power No power flowing to Cycle monitor off and on in case
lights on monitor monitor. power management has kicked in;
check power cable and replace;
check surge protector and replace;
replace monitor and retest.
Jittery picture quality LCD monitors display Use display-adjustment software to
not adjusted. reduce or eliminate pixel jitter and
pixel swim.
Cables loose. Check cables for tightness at the
video card and the monitor (if
removable).
Defective main or Remove the extender cable and
extender cable. retest with the monitor plugged
directly into the video card; if the
extended cable is bad, replace it; if
the main cable is bad, replace it.
Jitter is intermittent. Check for interference; microwave
ovens near monitors can cause
severe picture distortion when
turned on.