Apple PowerBook (2400c) - Manual (Page 59)

Trouble with the external monitor?
m Nothing happened when you tried to turn on the PowerBook.
Make sure that all your equipment is connected properly, then try pressing
the Power (π) key again.
Make sure that the battery is charged, or that the power adapter is plugged
into both the computer and an electrical outlet. If you are using a power
strip, make sure it is turned on.
m The computer is on, but the external monitor is dark.
Make sure that the monitor’s power cord is connected and that its power
switch is on. Try adjusting the monitor’s brightness and contrast settings. If
this doesn’t work, try restarting your computer.
Note: The screen-dimming feature in the PowerBook control panel turns the
screen brightness down to a low level when you haven’t used the computer for
a few minutes. (You can think of dimming as “screen sleep.”) Dimming also
affects the external monitor. When you move your finger on the trackpad or
press a key on the keyboard, the brightness is restored on both screens. For
more information on screen dimming, see the “Batteries & Power” topic area
of Mac OS Guide, available in the Guide (h) menu.
59 Using PC Cards and Additional Equipment