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GNS 400W Series Maintenance Manual
Page 4-57
190-00356-05
Rev. A
Replace CDU
Return the unit for service
Display Dim Test
Replace Inverter Board
Replace CDU
Return the unit for service
Keyboard LED Dim Test
Check Applicable Flex
Replaced Keyboard
Replace CDU
Return the unit for service
GPS Receiver Sensitivity
Replace GPS Module
GPS Antenna Bias
Replace GPS Module
GPS Signal
Replace GPS Module
Return the unit for service
Time Mark Output
Replace GPS Module
4.9
RETURN TO SERVICE TEST
When a board is replaced and the unit has been reassembled, verify that the power-up self-test
sequence is successfully completed and no failure messages are displayed. Ground checks that
are described in the GNS 400W Installation Manual may be adapted for bench checkout and may
be useful in verifying that a reassembled unit is working properly. The minimum performance
tests contained in this section of the manual may also be used as a return to service test.
