Furuno FS-1503, Service Manual

Page: 81 / 136

5-12
5.6 Measurements and Adjustment
CAUTION: Do not turn any adjusters until you understand their functions. The
measuring instruments must be calibrated before using.
Electrical Shock Hazard:
This equipment contains high voltages which can cause death at several
internal circuits. Any internal adjustment, servicing and repair shall only be
perfomed by qualified service personnel totally familiar with electrical circuits
and servicing of the equipment. A residual charge remains in capacitors and
other devices several minutes after turning off the power.
It is therefore essential to wait at least 3 minutes to allow residual charge to
subside before acceessing the inside of the equipment.
DANGER
1. Adjustment
Table 5-2 Adjustment (1/2)
Board Item Setting Adjuster Check Point Level Remarks
Overvoltage
protector Input voltage: 17.0 to
18.5 V
- - Power: off
PA
temperature
Temperature: 25
°
C -
J1 #7 (H) and
9 (C)
1.0
±
0.1 V
DRIVE
TR (Q4/Q5)
BIAS
Disconnect
[EXC IN], PTT ON
- R69 40 to 60 mV
PA/FIL
(050667)
PA TR
(Q6/Q7)
BIAS
Disconnect
[EXC IN], PTT ON
R39 FL3
500 mA
±
50 mA
CPU
(05P0665) Contrast
Adj.
- R1
TP1 (H) and
TP2 (C)
3.3
±
0.05 V
Use high Z
voltmeter.
Output
power Adj.
Input voltage: 13.6 V R15
J2 #1 (H) and
3 (C)
13.0 V
SW REG
(05P0668)
Oscillation
Freq Adj.
Input voltage: 13.6 V -
TP1 (H) and
TP2 (C)
170 kHz
±
20 kHz
(22 Vpp)
Optional
COUP
(05P0669)
Phase Det.
Balance
Adj.
- R24 - Mid. point
May be changed
to fixed resistor