Lcd Display Related - Micros Systems Workstation 4 LX Service Manual

WS4 Troubleshooting

LCD Display Related

LCD Display Related

This section lists all LCD display related issues. First, the blank or dark display issues
are addressed, the we move on to situations where the display is functional, but
experiences visual problems.
Let's define the terms "Dark LCD" and "Blank LCD", used throughout this section.
• Dark LCD indicates that the LCD backlights do not turn on. Any text or graphics
would not be visible under normal lighting conditions.
• Blank LCD indicates that the LCD backlights are on, but no text or graphics
appear on the screen.
Dark LCD (No Backlight)
Symptoms: The backlights are off, but the unit appears to boot normally (the unit
produces a single beep, the Operator LED is flashing Amber, and turns solid Green
after about 55 seconds).
• Defective Backlight Inverter Board.
• Defective Backlight Inverter Cable.
• Defective Backlight Pre-Regulator circuit on System Board - check System Board
fuse F5.
Blank LCD (No Video)
Symptoms: The backlights are on, the unit appears to boot normally (the beeper
sounds once, the LED is flashing Amber and turns solid Green after about 55
seconds), but no video appears.
• Loose connection between the display board and the LCD panel.
• Damaged or defective FB29 in series with TFTVDD at System Board connector
J15-12. Make sure TFTVDD is +3.3V.
Flickering LCD
Symptoms: The flickering appears during the blue screen and after the workstation
boots.
• Inverter Board
• Check for cold solder joints on L3 of the inverter board. The inductor may
need re-soldering.
• Disconnected backlight tube(s), or bent/corroded pins on the inverter
connector(s).
• Defective backlight tube(s).
LCD Backlight too Dim
Symptoms: The backlight(s) are very DIM at power-up and do not improve as the
operating temperature rises.
• Inverter Board.
3-14 Workstation 4 and 4 LX Field Service Guide