Garmin GPS 155 Repair Manual

Also see for GPS 155: Pilot's guide addendum

Garmin GPS 155 Repair Manual Manual pdf 10 page image

SECTION 2TROUBLESHOOTING2.1 TROUBLESHOOTING EQUIPMENT REQUIRED• 0-30 Volt DC / 3-Amp Power Supply• Digital Multimeter• 20 MHz Oscilloscope2.2 SELF-TEST FAILURESThe GPS 155 monitors many of its internal functions and displays a message to alert the user should afailure occur. The table below shows the recommended repair for each self-test failure message.MESSAGE RECOMMENDED REPAIR*Altitude input failVerify connections to altitude serializer/encoderReplace Altitude Decoder Board (see Section 3.2.2)Replace Interface Board (see Section 3.2.3)Replace Main Board (see Section 3.2.4)Battery rqrs service Verify connection of external battery pack to Main BoardReplace external battery pack(see Section 3.2.6)Course input fail Check ARINC 429 / RS-422 course input connectionsReplace Main Board (see Section 3.2.4)Data card failed Replace NavData® cardReplace Interface Board (see Section 3.2.3)Data card write fail Replace user data cardReplace Interface Board (see Section 3.2.3)Fuel/Air input fail Check connections to fuel/air data systemReplace Main Board (see Section 3.2.4)Memory battery low Replace memory battery (see Section 4.1)No altitude inputVerify connections to altitude serializer/encoderReplace Altitude Decoder Board (see Section 3.2.2)Replace Main Board (see Section 3.2.4)Osc needs adjustment Replace RF/IF Assembly (see Section 3.2.5)Replace Main Board (see Section 3.2.4)RAM failed Replace Main Board (see Section 3.2.4)Receiver failed Replace Main Board (see Section 3.2.4)Replace RF/IF Assembly (see Section 3.2.5)ROM failed Replace ROM (see Section 4.2)Replace Main Board (see Section 3.2.4)Stored data lost Replace memory battery (see Section 4.1)* Where multiple repair actions are listed, they are listed with the most likely failure cause presented first.7