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22. Maintenance and Troubleshooting
22-10
Problem Probable causes or
check points
Remedy
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
feeder line
5) Second trace echo
rejection 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
below normal value, MIC may have
become 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 2.24 How to
Suppress Second-trace Echoes.
Range changed but radar picture
not changing
1) Defective range key
2) SPU board
3) Video freeze-up
1) Try to hit RANGE key several times. If
unsuccessful, replacement of keypad may be
required.
2) Replace SPU board.
3) Turn off and on radar.
Interference rejector is
inoperative (interference
rejection level not displayed)
SPU board Replace SPU board.
Echo stretch is ineffective
(neither ES1, ES2 nor ES3 is
displayed)
SPU board 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) SPU board
1) Replace associated circuit board if
unsuccessful.
2) Replace SPU board.
Poor discrimination in range Sea clutter control not
functioning properly
Improper setting of A/C SEA. If A/C SEA is
seen only at very close range, suspect inaccurate
frequency of reference oscillator.
True motion presentation not
working correctly
1) Poor contact of MODE key
(full keyboard)
2) Selection not accessed.
3) Speed entry incorrect
4) TM display inaccurate
1) Try to press MODE key a little harder.
2) Press MODE key or operate
PRESENTATION MODE box until TM
appears.
3) Enter correct own ship speed referring to
section 2.5 How to Input Your Ship's Speed.
4) Make sure that speed and compass
inputs are accurate.
Target not tracked
correctly
Poor definition of targets in sea
clutter
Adjust A/C SEA and A/C RAIN controls
referring to section 2.8 How to Suppress Sea
Clutter and 2.9 How to Suppress Rain Clutter.
Buttons on trackball module
operated but no response
Trackball module Replace trackball module.