Furuno SC-33 Operator's Manual page 33

Symptom
Heading is not output.
Heading output stops often.
Position and GNSS-related
items are output but heading
is not
Equipment in NMEA 2000
network malfunctions when
SC-33 is connected.
Heading is output normally in
fine weather but is not output
in bad weather.
Autopilot jerks suddenly.
Possible cause and remedy
Check installation site;
• Check for interfering objects near the antenna.
• Check the installation site and mounting base for vibration.
• Check for antenna of radar, radio equipment, etc. near the instal-
lation site.
Check connections;
1) NMEA 2000 bus connection
• Check that the connector on the SC-33 is tightly connected.
• Check that no stress is applied to the cable and that a loop has
been made with the cable to prevent cable stress.
• Check that terminators (120 ohm) are attached at each end of
the NMEA 2000 network.
• Check that the input voltage to the SC-33 is between 9 to 32
VDC.
• Check that all devices connected to the NMEA 2000 bus are
within the current capacity of the bus.
• Check that the cable (FRU-NMEA-PMMF-060 (6m)) is used.
(If power is fed through a trunk line, the feeder cable shall be
no longer than 6 m).
• If power to the SC-33 is fed directly from the ship's mains,
check breaker switch on mains switchboard and fuse in power
cable.
2) IF-NMEASC interface unit connection:
See the IF-NMEASC's operator's manual.
• Check for obstructions near the SC-33.
• Check installation site for vibrations.
• Check if other antennas (radar, radio, etc.) are near the instal-
lation site.
• Check that terminators (120 ohm) are attached at each end of
the NMEA 2000 network.
• Check that the input voltage to the SC-33 is between 9 to 32
VDC.
• Check that all devices connected to the NMEA 2000 bus are
within the current capacity of the bus.
• Check that the cable (FRU-NMEA-PMMF-060 (6m)) is used. (If
power is fed through a trunk line, the feeder cable shall be no lon-
ger than 6 m).
• Check the installation site for vibrations.
• Check for obstructions near the SC-33.
• Check the installation site and mounting base for vibrations.
• Check if other antennas (radar, radio, etc.) are near the instal-
lation site.
• Check operation at the autopilot:
1) Check that the rudder angle can be confirmed when heading
output has stopped. Check that the necessary alarms are out-
put. Confirm that the rudder returns to 0° and the set rudder
angle is maintained.
2) Confirm that rudder does not jerk violently when heading out-
put is resumed. For example, check that the setting for rudder
angle limit is suitable.
26
5. MAINTENANCE, TROUBLESHOOTING