G900X/G950 Installation and Maintenance Manual – Troubleshooting
Page D-29
190-00719-00
Revision D
D.4 GDU Related Alerts and Problems
D.4.1 General Problems
Symptom Recommended
Action
Display will not track photocell
Keyboard will not track
photocell
•
Go to the GDU TEST page in configuration mode. Cover and
uncover the photocells and verify that PHOTOCELL A or
PHOTOCELL B value changes.
−
If values do not change, replace the display.
•
Reload GDU configuration files.
Display will not track dimmer
bus
Keyboard will not track
dimmer bus
•
Reload GDU configuration files.
•
Swap PFD or MFD to see if problem remains with display.
−
Replace display if condition remains with the same unit.
−
If condition remains in original position after swapping
displays, check GDU dimmer input to verify voltage is
present.
Display is blank
Display resets
Display flickers
•
Ensure that a cell phone or a device using cell phone technology
is not turned on (even in a monitoring state) in the cabin.
•
Cycle
power.
−
If GDU recovers, observe display for yellow text containing
error information at the top of the screen. If message
indicates software need to be re-loaded, then re-load
software. Otherwise, replace the GDU.
•
Use a bright light to verify LCD is active.
−
Adjust avionics dimmer control full clockwise.
−
Manually turn up backlight on the PFD and load configuration
files to the GDU.
•
Ensure slide lock is fully engaged with the locking tabs on the
back of the unit.
−
If slide lock is not fully engaged, remove connector and verify
the locking tabs on the GDU are perpendicular to the
connector. If necessary, straighten them before reseating
connector.
•
Ensure GDU is receiving power. If a circuit breaker is tripped,
determine source of short before resetting breaker.
•
Ensure circuit breakers have not failed and power wire
connections are secure.
•
Swap PFD or MFD.
−
If problem follows unit, replace the display. Please note the
position it failed in (PFD1) OR MFD.
−
If problem does not follow unit, troubleshoot aircraft wiring for
fault.
