Furuno FAR-1513-BB Operator's Manual page 156

6. MAINTENANCE, TROUBLESHOOTING
Problem
Marks, indications and
noise appear but no
echo (transmission
leak representing own
ship position is absent)
Picture not updated or
picture freeze-up
Incorrect orientation of
picture
Cannot operate radar
from on-screen boxes
Radar is properly tuned
but poor sensitivity
Range changed but ra-
dar picture not chang-
ing
Interference rejector is
inoperative (interfer-
ence rejection level not
displayed)
Echo stretch is ineffec-
tive (neither ES1, ES2
nor ES3 is displayed)
Range rings are not
displayed
Poor discrimination in
range
6-6
Possible cause
1) TX high voltage protec-
tion circuit has activated.
2) Magnetron
3) Modulator board
4) SPU board
1) Bearing signal generator
board (in antenna unit)
2) SPU board
3) Video freeze-up
1) Terminal board: RFTB/
RTB (inside transceiver
unit) or FRP_TB board
(inside processor unit)
2) SPU board
SPU board
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) Defective range key
2) SPU board
3) Video freeze up
SPU board
SPU board
1) Adjust the brilliance of
range rings on the BRILL
menu to see if intensity is
increased
2) SPU board
Sea clutter control not func-
tioning properly
Remedy
1) Reset power to restore normal opera-
tion.
2) Check magnetron current.
Replace magnetron.
3) Replace modulator board.
4) Replace SPU board.
1) Check the connection of signal cables.
2) Replace SPU board.
3) Turn the radar off, then on.
If the message "NO HEADLINE SIGNAL"
appears in orange letters inside the alert
box, the heading signal is lost or interrupt-
ed. Check the heading line signal cable
and terminal board connections. If there is
no problem with cables or connections, re-
place the SPU board.
Replace SPU board.
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 1.28.
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.
Replace SPU board.
Replace SPU board.
1) Replace associated circuit board if un-
successful.
2) Replace SPU board.
Improper setting of A/C SEA. If A/C SEA is
seen only at very close range, suspect in-
accurate frequency of reference oscillator.