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22. Maintenance and Troubleshooting
22-7
22.6 Advanced-Level Troubleshooting
This section describes how to cure hardware and software troubles that should be carried out by qualified service
personnel.
Note: This radar equipment contains complex modules in which fault diagnosis and repair down to component level
are not practicable by users.
Advanced troubleshooting
Problem
Probable causes or
check points
Remedy
Power turned on but radar does
not operate at all
1) Blown fuse.
2) Mains voltage/polarity
3) Power supply board
1) Replace blown fuse.
2) Correct wiring and input voltage.
3) Replace power supply board.
Brilliance adjusted but no
picture
SPU board Replace SPU board.
Antenna not rotating 1) Antenna drive mechanism
2) Defective antenna drive
motor relay (thermal relay K2,
200/220/380, 440/100 VAC)
1) Replace antenna drive mechanism.
2) Press relay reset button.
Data and marks not displayed
in Transmit status
SPU board Replace SPU board.
Adjust GAIN with A/C SEA
set at minimum. Marks and
indications appear but no noise
or echo
1) IF amplifier
2) Signal cable between
antenna and processor
unit
3) Video amplifier board
1) Replace IF amplifier.
2) Check continuity and isolation of coaxial
cable.
Note: Disconnect the plug and lugs at both
ends of coaxial cable before checking it by
ohmmeter.
3) Check video coax line for secure
connection. If connection is good, replace
SPU board.
Marks, indications and noise
appear but no echo
(Transmission leak
representing own ship position
is absent)
1) TX high voltage
protection circuit has activated.
2) Magnetron
3) Modulator board
4) SPU board
1) Reset power to restore normal operation.
2) Check magnetron current.
Replace magnetron.
3) Replace modulator board.
4) Replace SPU board.
Picture not updated or picture
freeze-up
1) Bearing signal generator
board (in antenna unit)
2) SPU board
3) Video freeze-up
1) Check the connection of signal cables.
2) Replace SPU board.
3) Turn off and on the radar.
Incorrect orientation of picture
1) SPU board
2) Gyro interface
1) The message GYRO appears when the
heading pulse is not received during standby.
2) Replace the gyro interface.
Cannot operate radar from on-
screen boxes
SPU Board Replace SPU Board.