IBM P72 Operating Instructions Manual page 22

Additional Information
Symptom
Screen image is not centered
or sized properly
Edges of the image are
curved
White lines show red or blue
shadows at edges
Picture is fuzzy
Picture bounces or has wavy
oscillations
Picture is flickering
Picture appears to be
ghosting
Wavy or elliptical (moire)
pattern is visible
Two fine horizontal lines
(wires) are visible
Hum is heard right after the
power is turned on
16
Check these items
• Adjust the size or centering (pages 5 – 6).
• Some video modes do not fill the screen to the edges. This problem tends to occur with
certain video boards.
• Adjust the geometry (pages 6 – 7).
• Adjust the convergence (pages 9 – 10).
• Adjust the contrast and brightness (page 4).
• Degauss the monitor (page 10).
If you place equipment which generates a magnetic field, such as a loudspeaker, near
the monitor, or you change the direction of the monitor, color may lose uniformity.
The degauss function demagnetizes the metal frame of the CRT to obtain a neutral
field for uniform color reproduction. If a second degauss cycle is needed, allow a
minimum interval of 20 minutes for the best result.
• If red or blue shadows appear along the edges of images, adjust the convergence
(pages 9 – 10).
• If the moire is cancelled, the picture may become fuzzy. Decrease the moire
cancellation effect (pages 9 – 10).
• Isolate and eliminate any potential sources of electric or magnetic fields. Common
causes for this symptom are electric fans, fluorescent lighting or laser printers.
• If you have another monitor close to this monitor, increase the distance between them
to reduce the interference.
• Try plugging the monitor into a different AC outlet, preferably on a different circuit.
• Try the monitor on a different computer in a different room.
• Set the refresh rate on the computer to obtain the best possible picture by referring to
your computer's manual.
• Eliminate the use of video cable extensions and/or video switch boxes if this symptom
occurs. Excessive cable length or a weak connection can produce this symptom.
• Cancel the moire (pages 9 – 10).
The moire may be modified depending on the connected computer.
• Due to the relationship between resolution, monitor dot pitch and the pitch of some
image patterns, certain screen backgrounds sometimes show moire. Change your
desktop pattern.
• These wires stabilize the vertically striped aperture grille (page 14). This aperture grille
allows more light to pass through to the screen giving the Trinitron CRT more color
and brightness.
• When the power is turned on, the auto-degauss cycle is activated. While the auto-
degauss cycle is activated, a hum may be heard. The same hum is heard when the
monitor is manually degaussed. This is not a malfunction.