Troubleshooting; Troubleshooting Equipment Required; Self-Test Failures - Garmin GPS 155 Repair Manual

2.1

TROUBLESHOOTING EQUIPMENT REQUIRED

• 0-30 Volt DC / 3-Amp Power Supply
• Digital Multimeter
• 20 MHz Oscilloscope
2.2

SELF-TEST FAILURES

The GPS 155 monitors many of its internal functions and displays a message to alert the user should a
failure occur. The table below shows the recommended repair for each self-test failure message.
MESSAGE
Altitude input fail
Battery rqrs service
Course input fail
Data card failed
Data card write fail
Fuel/Air input fail
Memory battery low
No altitude input
Osc needs adjustment
RAM failed
Receiver failed
ROM failed
Stored data lost
* Where multiple repair actions are listed, they are listed with the most likely failure cause presented first.
SECTION 2

TROUBLESHOOTING

RECOMMENDED REPAIR*
Verify connections to altitude serializer/encoder
Replace Altitude Decoder Board (see Section 3.2.2)
Replace Interface Board (see Section 3.2.3)
Replace Main Board (see Section 3.2.4)
Verify connection of external battery pack to Main Board
Replace external battery pack(see Section 3.2.6)
Check ARINC 429 / RS-422 course input connections
Replace Main Board (see Section 3.2.4)
Replace NavData® card
Replace Interface Board (see Section 3.2.3)
Replace user data card
Replace Interface Board (see Section 3.2.3)
Check connections to fuel/air data system
Replace Main Board (see Section 3.2.4)
Replace memory battery (see Section 4.1)
Verify connections to altitude serializer/encoder
Replace Altitude Decoder Board (see Section 3.2.2)
Replace Main Board (see Section 3.2.4)
Replace RF/IF Assembly (see Section 3.2.5)
Replace Main Board (see Section 3.2.4)
Replace Main Board (see Section 3.2.4)
Replace Main Board (see Section 3.2.4)
Replace RF/IF Assembly (see Section 3.2.5)
Replace ROM (see Section 4.2)
Replace Main Board (see Section 3.2.4)
Replace memory battery (see Section 4.1)
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