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Page iv
GNS 400W Series Maintenance Manual
Rev. A
190-00356-05
TABLE OF CONTENTS
SECTION 1—INTRODUCTION
1.1 Maintenance/Support
Philosophy ............................................................................. 1-1
1.2 Unit
Upgrades ........................................................................................................... 1-1
1.3 Factory
Repair........................................................................................................... 1-1
1.4 Warranty
Information ............................................................................................... 1-2
SECTION 2—UNIT DESCRIPTION
2.1 Introduction............................................................................................................... 2-1
2.2
Front Panel Layout.................................................................................................... 2-2
2.3 Unit
Functions........................................................................................................... 2-2
2.4 Technical
Specifications ........................................................................................... 2-4
SECTION 3—THEORY OF OPERATION
3.1 Main
Board ............................................................................................................... 3-1
3.2
VHF Communications Transceiver (Com Board) .................................................... 3-3
3.3 Nav
Board ................................................................................................................. 3-4
3.4 Glideslope
Receiver .................................................................................................. 3-4
3.5
WAAS GPS Receiver ............................................................................................... 3-4
3.6 Inverter
Board ........................................................................................................... 3-4
3.7 Interface
Board ......................................................................................................... 3-5
3.8 Video
Board .............................................................................................................. 3-5
3.9 Keyboard................................................................................................................... 3-5
SECTION 4—TROUBLESHOOTING/TESTING
4.1 Introduction............................................................................................................... 4-1
4.2 Limitation/Scope....................................................................................................... 4-1
4.3
Troubleshooting Method I – Failure Messages ........................................................ 4-1
4.4
Troubleshooting Method II – Minimum Performance Tests .................................... 4-7
4.5
Comm Board Tests ................................................................................................. 4-20
4.6
VOR/LOC Receiver Testing................................................................................... 4-44
4.7
Glideslope Receiver Tests....................................................................................... 4-53
4.8 Testing
Failures....................................................................................................... 4-56
4.9
Return To Service Tests.......................................................................................... 4-57
