Garmin GNS 480 Installation Manual page 121

Problem
• GNS 480 ARINC 429 input not
GNS 480 is not
receiving heading
from compass system
• ARINC 429 input port speed not
(ARINC 429 heading
input used)
• Wiring connections are incorrect.
• Heading Valid input invalid.
GNS 480 is not
receiving heading
from compass system
(synchro heading input
• 26VAC reference voltage is
used)
• Wiring connections are incorrect
• Synchro X,Y,Z legs are crossed
GNS 480 heading
differs greatly from
• 26VAC reference Hi and Lo are
compass system
(synchro hdg only)
• 26VAC reference supplied to GNS
• GNS 480 baro pot input not
GNS 480 is not
receiving baro-
correction setting from
• GNS 480 baro pot input not
altimeter
• GNS 480 is not the only device
• GNS 480 does not have a position
Autopilot is not
getting GPSS/Roll
Steering data from the
• GNS 480 ARINC 429 output not
GNS 480 (ARINC 429
Roll Steering used)
• ARINC 429 output port speed not
• Wiring connections are incorrect.
• GNS 480 RS232 output not
Autopilot is not
getting GPSS/Roll
Steering data from the
• Wiring connections are incorrect.
GNS 480 (RS232 Roll
Steering used)
• Desired RMI source has not been
RMI pointer does not
indicate correctly
• Wiring connections are incorrect.
• DME Select is not low
Tuning data not
updating DME
• Wiring connections are incorrect.
GNS 480 (CNX80) Installation Manual560-0982-01 Rev A
Table 4-1. Troubleshooting Guide
Possible Cause
configured correctly.
correct
incorrect
swapped.
480 is different than 26VAC
reference used by compass system.
configured correctly.
calibrated
tied to the altimeter baro pot
or flight plan entered.
configured correctly.
correct
configured correctly.
selected
Solution
•
Check ARINC 429 input port setting for
port that device is connected to.
•
Check ARINC 429 input port speed
setting for port that device is connected
to and verify that the speed is correct for
that device.
•
Check wiring.
•
Check that heading valid input (P5-57)
is > 9 VDC. State of this input can be
checked in Ground Maintenance Mode.
•
Check that 26VAC, 400Hz reference is
supplied to P5-20,39
•
Check wiring.
•
Check wiring.
•
Check wiring.
•
Verify that GNS 480 and compass
system are using the same 26VAC
reference.
•
Check baro pot configuration in Ground
Maintenance Mode
•
Calibrate baro pot
•
Ensure GNS 480 is the only device
connected to the altimeter baro pot
•
Acquire GPS position and enter a flight
plan.
•
Check ARINC 429 output port setting
for port that autopilot is connected to.
•
Check ARINC 429 output port speed
setting for port that autopilot is
connected to and verify that the speed is
correct for autopilot.
•
Check wiring.
•
Ensure output port setting is MAPCOM
for port that autopilot is connected to.
•
Check wiring.
•
Select desired RMI source from Nav or
GPS.
•
Check wiring
•
Verify DME Select pulled low.
•
Check wiring.
Troubleshooting
4-3