Poor Sensitivity - Furuno FR-1505 MARK-3 Series Service Manual

Symptom: Poor sensitivity
Flow chart 8
Check TOTAL ON
TIME/TOTAL TX TIME.
Less than
2000 hrs ?
OK
Manual tuning ?
OK
Check maximum. gain is
obtained with maximum
tuning indication.
OK ?
OK
Perform Tuning
Initialization.
OK
Defective EEPROM,
Defective back-up ckt
NG
Replace
magnetron.
NG
NG
Defective IF amp.
Defective MIC
Defective IF amp.,
NG
MIC, or SPU board.

Poor sensitivity

No echo; poor
sensitivity.
No echo (White noise appears)
approx. 12V
Check if display unit
outputs TX trigger.
(DJ-1 #4)
NG
(No TX trigger)
Rating ?
OK
Check TUNE voltage
output from display unit.
NG
DJ-1#7 is normal ?
OK
TUNE IND voltage in manual mode ;
In manual mode, rotate
about 1 to 3 V
TUNE VR and check
the voltage.
NG
TP1 on SPU ?
OK
Check input video
signal at U90 #1 on
approx. -4V
SPU.
NG
OK?
OK
Faulty pcb 03P9230.
5-10
To 1)
(page 5-11)
0V
Faulty pcb 03P9230.
Manual Tune Voltage :
about 2 V to 32 V
Faulty pcb 03P9230.
To 2)
(page 5-12)
0V
Defective IF AMP (03P9232)
FR1710-SME-68