This is from the PV troubleshooting manual
Screen objects are not visible.
1. Correct power is not applied.
2. Contrast or intensity is not set correctly.
3. Terminal is in screen saver mode.
4. PV550 backlight lamp is not on.
5. Terminal’s backlight is burnt out.
1. Verify power connections.
2. Access Screen Setup on the Configuration Mode
menu and adjust the contrast. On keypad
terminals, press the left and right arrow keys
simultaneously, then press [F9] or [F15].
3. Access Screen Setup on the Configuration Mode
menu to see if terminal is set for screen saver
mode.
4. Access Screen Setup on the Configuration Mode
menu and turn on backlight.
5. Replace backlight.
To access Configuration Mode on keypad terminals:
· If an application is running, simultaneously press the Left and
Right arrow keys on the terminal keypad.
To access Configuration Mode on touch screen terminals:
· press the GoTo Config. Screen button on application screen or
· press the filled box in the lower right corner of the screen
during powerup.