6. MAINTENANCE, TROUBLESHOOTING
6-7
Marks, indications and
noise appear but no
echo (transmission
leak representing own
ship position is absent)
1) TX high voltage protec-
tion circuit has activated.
2) Magnetron
3) MD board inside the an-
tenna.
4) SPU board inside the an-
tenna.
1) Reset power to restore normal opera-
tion.
2) Check magnetron current.
Replace magnetron.
3) Replace MD board.
4) Replace SPU board.
Picture not updated or
picture freeze-up
1) Rotary Encoder inside
the antenna unit.
2) SPU board inside the an-
tenna.
3) Video freeze-up
1) Check the connection of signal cables.
2) Replace SPU board.
3) Turn the radar off, then on.
Incorrect orientation of
picture
1) Rotary Encoder inside
the antenna unit
2) SPU board inside the an-
tenna unit.
3) MTR-DRV board inside
the antenna unit.
If the message “LOST HEADLINE” ap-
pears in orange letters inside the alert box,
the heading signal is lost or interrupted.
Check the heading line signal cable and
board connections. If there is no problem
with cables or connections, replace the
faulty board.
Cannot operate radar
from on-screen boxes
MAIN board - inside the Pro-
cessor unit.
Replace MAIN board.
Radar is properly tuned
but poor sensitivity
1) Deteriorated magnetron
2) Detuned MIC
3) Dirt on radiator face
4) Water ingress to the
waveguide or other feed-
er line
5) Second trace echo rejec-
tion is ON
1) With the radar transmitting on 48 nm
range, check magnetron current. If
current is below normal, magnetron
may be defective. Replace it.
2) Check MIC detecting current. If it is be-
low normal value, MIC may have be-
come detuned. MIC must be tuned.
3) Clean the radiator surface.
4) Remove water from the feeder line.
5) Disable the second-trace echo rejector
referring to section 1.29.
Range changed but ra-
dar picture not chang-
ing
1) Defective range key
2) SPU board inside the an-
tenna.
3) Video freeze up
1) Adjust the range with the control unit,
or the [RANGE] box several times. If
unsuccessful, replacement of keypad
may be required.
2) Replace SPU board.
3) Turn off and on radar.
Interference rejector is
inoperative (interfer-
ence rejection level not
displayed)
SPU board inside the anten-
na.
Replace SPU board.
Echo stretch is ineffec-
tive (neither ES1, ES2
nor ES3 is displayed)
SPU board inside the anten-
na.
Replace SPU board.
Range rings are not
displayed
1) Adjust the brilliance of
range rings on the BRILL
menu to see if intensity is
increased
2) MAIN board
1) Replace associated circuit board if un-
successful.
2) Replace MAIN board.
Problem Possible cause Remedy
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