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GNS 400W Series Maintenance Manual
Page 4-7
190-00356-05
Rev. A
4.4
TROUBLESHOOTING METHOD II – MINIMUM PERFORMANCE TESTS
When the fault message method is unsuccessful, the following minimum performance tests may
be performed to help troubleshoot and identify a defective board. Replace the defective part or
send the unit to Garmin if the unit fails to pass any test.
NOTES
A misaligned board may cause incorrect test results. Alignment cannot be
performed by the avionics shop. Send the unit to Garmin for repair.
The main board contains an EEPROM memory storage device which must be
programmed with Unit Configuration, TAWS/Terrain Configuration, and Unit
Serial Number. Because of this, the main board is not replaceable in the field.
Replace the main board if any of the main board tests fail.
All voltage measurements are relative to ground (J1-77 or J1-70) unless
otherwise stated.
4.4.1 UNIT TEST AND CONFIGURATION PAGES
NOTE
Actual test and configuration pages may vary from what is shown in this section.
All pages were current at the time of manual publication but are subject to
change due to software updates, etc.
The results of certain tests can be monitored using the test and/or configuration pages. To display
the test pages, ground the test pin (J1-76) and apply power. When in test mode, specific test pages
can be selected by turning the small right knob. Table 4-2 lists the test and configuration pages
and their names.
To display the configuration pages, press and hold the ENT key and apply power. Release the
ENT key when the display activates. Test and/or configuration pages can be selected by turning
the small right knob.
To change data on the test or configuration pages, press the small right knob (CRSR) to turn on
the cursor. Rotate the large right knob to change between data fields. Rotate the small right knob
to change a field that the cursor is on. Once a selection has been made, press the ENT key to
accept the entry.
NOTE
Do not make changes to any of the test or configuration page fields which are not
required to perform testing.
