Furuno FAR-2805 Series Operator's Manual page 92

Problem
Interference rejector
inoperable (interference
rejection level not
displayed)
Echo stretch ineffective
(Neither "ES1" nor "ES2" is
displayed.)
Only 2 parallel index lines
(6 lines wanted)
Range rings are not
displayed.
Key beep inaudible
Poor discrimination at
range
True motion presentation
not working correctly
Target not tracked correctly 1. Poor definition of targets in
5-4
Check point and
probable cause
1. Bad contact of key
2. SPU Board
3. Mother Board
1. Bad contact of key
2. SPU Board
1. Incorrect setting of index
line interval
1. Press RINGS key to see if
intensity is increased.
control to see if intensity is
increased.
2. Bad contact of key
3. SPU Board
1. Improper setting on
RADAR 2 menu
1. Sea clutter control not
functioning properly.
1. Poor contact of MODE
key.
2. Selection is not accessed.
3. Speed entry is incorrect.
4. TM display inaccurate
sea clutter
Remedy
1. Repair contact of key.
2. Replace SPU Board.
3. Replace Mother Board.
1. Repair contact of key.
2. Replace SPU Board.
1. Set index line interval referring to
paragraph 1.26.
1. Replace associated circuit board if
unsuccessful.
2. Replace keypad.
3. Replace SPU Board.
1. Adjust key beep level on
RADAR 2 menu referring to
paragraph 1.32.
1. Improper setting of A/C SEA
control. If A/C SEA is seen only
at very close range, suspect
inaccurate frequency of
crystal oscillator.
1. Try to press MODE key a little
harder.
2. Press MODE key until "TM"
appears.
3. Enter correct own ship speed
referring to paragraph 1.24.
4. Make sure that speed and compass
inputs are accurate.
1. Adjust A/C SEA and A/C RAIN
controls referring to paragraphs
1.13 and 1.14.