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6. MAINTENANCE, TROUBLESHOOTING
6-5
6.6 Advanced-level Troubleshooting
This section describes how to cure hardware and software troubles which only quali-
fied service persons must do.
Problem
Possible cause or check
points
Remedy
Power cannot be turned on. 1) Mains voltage/polarity
2) Power supply board
1) Correct the wiring and input
voltage.
2) Replace the power board.
Brilliance adjusted but no
picture.
1) SPU Board 1) Replace SPU Board.
Antenna not rotating. 1) Antenna drive mechanism 1) Replace the antenna drive
mechanism.
Data and marks not dis-
played in transmit.
1) SPU board 1) Replace SPU board.
Set GAIN to the maximum
with A/C SEA set at mini-
mum. Marks and indications
appear but no noise or echo.
1) Signal between antenna and
display unit
2) IF amplifier
3) Video amplifier board
1) Check continuity and isola-
tion of coaxial cable.
2) Replace IF amplifier.
3) Check coax line for fasten
connection. If the connection
is good, replace SPU board.
Marks, indications and noise
appear but no echo. (Trans-
mission leak show your ship
position is not present.)
1) Magnetron
2) Modulator board
3) SPU board
1) Check magnetron current.
2) Replace modulator board.
3) Replace the SPU board.
Picture not updated or pic-
ture freeze-up.
1) Bearing signal generator
2) SPU board
3) Video freeze-up
1) Make sure that the signal ca-
bles are fastened.
2) Replace the SPU board.
3) Turn the radar off, then on.
Radar is correctly tuned but
sensitivity is weak.
1) [2nd Echo Rejector] is [ON]
2) Dirt on radiator face
3) Deteriorated magnetron
4) Detuned MIC
1) Turn off the [2nd Echo Rejec-
tor] from the [Echo] menu.
2) Clean the radiator.
3) Check the magnetron current
with the radar transmitting on
48 nm range. If the current is
below normal, magnetron
may be defective. Replace
the magnetron.
4) Check the MIC detecting cur-
rent. If MIC detecting current
is below normal value, the
MIC may be detuned.
Range changed but picture
does not change.
1) RANGE key has defaults
2) SPU board
3) Video freeze-up
1) Try to operate the RANGE
key. If you can not operate
the RANGE key, replace the
keypad.
2) Replace the SPU board.
3) Turn the radar off, then on.
Range rings are not dis-
played.
1) Adjust their brilliance on the
[Brill/Color] menu.
2) SPU board
1) Replace the associated cir-
cuit board if unsuccessful.
2) Replace the SPU board.