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G1000 System Maintenance Manual
Page 5-91
190-00903-00
Rev.
A
'KEY' Window:
a.
KEY PWM
―
Displays the keypad pulse width modulation brightness value. Range is
between 0 and 9999 and corresponds to the keypad brightness value shown. Not useful for
troubleshooting.
b.
TOGGLE KEY BKLT OFF?
―
Allows the technician to toggle the keyboard backlight off.
c.
REINIT PAGE INFO?
―
Allows technician to re-initialize all information on the test page.
'ADC' Window:
a.
PHOTOCELL A, B
―
Displays the input value of display photocells, between 0 and 9999.
The values can be converted to a percentage by adding a decimal place two digits over from
the right (Example:
8035 = 80.35%). If there is a significant split (~30% to 50%) you can expect the display to
appear different from the other display in the aircraft, IF both of their lighting curves are set
to the same values. Replace the display if one photocell reading is significantly different
from the other.
b.
BEZEL THERM
―
Displays the temperature of the GDU bezel, expressed in degrees Celsius.
c.
CCFT CRNT 1, 2
―
Displays an indication of current flowing through the display backlight
bulbs. Number does not reflect actual current value and is not useful for troubleshooting.
d.
POWER (2.5V, 3.3V, 28 V 1, 2; 1.3V)
―
Displays power input voltages of various internal
components. (Example: for 2.5V field, 2500 = 2.500 Vdc; for 28V Field, 3633 = 36.33 Vdc)
They need to be within 10% of desired voltages. Replace the display if these values are more
than 10% from the desired voltage.
e.
LGHT BUS DC, AC
―
Displays input value of AC and DC lighting bus inputs, depending on
which is configured. Disregard number if not used in the installation.
f.
INTRNL TEMP 1, 2
―
Displays the internal temperature of the GDU, expressed in degrees
Celsius.
'TEST' Window:
a.
IIC EEPROM
―
Displays the condition of the GDU configuration module EEPROM chip,
located in the backplate connector. It should be green for the PFD and red for the MFD. If it
is red on the PFD, check configuration module wiring and pins for damage before replacing
the configuration module.
b.
DATACARD CHKSUM 1, 2
―
Requires the use of a special datacard. Tests the datacard
reader interface function. Used for Garmin testing, not useful for troubleshooting.
c.
NAND, NOR FLASH, SDRAM
―
Displays the condition of various GDU internal
components.
d.
A429 LOOP 1, 2
―
Indicated the status of the GDU 104Xs ARINC 429 channels. A green
box indicates the ARINC 429 loopback tests passed. A red or black box indicated it may not
be used or a wiring fault is present.
e.
ETHERNET 1, 2, 3
―
Indicates status of the GDU 104Xs Ethernet channel. A green box
indicates the ETHERNET loopback tests passed. A red or black box indicates it may not be
used or a wiring fault is present.
f.
RS-232 1, 2
―
Indicates status of the GDU 104X’s RS-232 channel. A green box indicates
the RS-232 loopback tests passed. A red or black box indicates it may not be used or a
wiring fault is present.