Epson EL 486UC - Manual (Page 106)

Keyboard Problems
The screen displays a keyboard error message when you
turn on of reset the computer.
Make sure the keyboard is securely connected to the correct
port.
Nothing happens when you type on the keyboard.
See “The Computer Does Not Respond,” above.
The cursor keys on the numeric keypad do not work
properly.
If the Num Lock light in the upper right corner of the keyboard
is lit, press NumLock to turn off the function.
If you want to change the initial settings of the num lock
function, see “Setting Keyboard Options” in Chapter 1.
Monitor Problems
There is no display on the screen.
Check that the monitor’s power switch is on and that its power
light is on.
The power light is on, but you still do not see anything on
the screen.
Check the brightness and contrast controls.
If you still do not see anything on the screen, make sure the
monitor is securely connected to the computer.
Troubleshooting 6-5