User`s guide

Hot Issues Black Screen, Distortion, or Misconvergence Caused by CRT Arc-
Solution: In some cases simply using the power switch on
the front panel of the monitor will eliminate the screen
distortion.
Otherwise, shut down the monitor and unplug the power cord
and ADB cables from the back of the monitor. Count to ten.
Then plug in the power cord and ADB cables. This action
should remove all symptoms. If the blank screen symptom
persists, contact Apple Technical Support.
CRT arcing is normal and expected on a certain percentage of
displays from all manufacturers. An arc happens when
residual particles inside the CRT are dislodged. This usually
occurs when the display has experienced physical vibration
like transportation. The arc time is short and there is no
safety hazard because the arc is contained inside the sealed
glass of the CRT. This arcing will not cause permanent
damage to the display.