Furuno FAR-2107 Series Service Manual page 363

CR2
Q3(2SJ265)
(D4F60)
+24V
(L1)
FILTER
TP1
-24V
PR+5V
+5V
U1 REG
(AN78L05)
Low
Voltage
Protect
U2(M519578FP)
Q1
- Low voltage protection circuit
+24V inputs from RPU-013 enter Q3 via the power supply filter circuit. The gate
of Q3 is controlled by signals of the low voltage protection circuit U2 and turns off
Q3 when the input voltage is reduced to +16.8 VDC or less. The starting voltage is
19.5 V or more.
- +12 V power supply circuit
U11 is the switching power supply of +12 VDC/1.7 A and operates at 60 kHz. Q11
and C13 connected to the SS terminals of U11 are circuits for output control and
soft start. The soft start function is provided to suppress the supply rush current of
the load. R13 to R16 and U12 are output overcurrent protection detection circuits
which controls the SS terminals of U11 when the current of 2.5 A to 3 A runs on
the +12 VDC line and stops the output of this line. The overcurrent protection
circuit is automatically reset.
－ 12 V power supply circuits
- +32 V,
The +12 VDC power supply also outputs to the switching power supply U41. U41
operated at 33 kHz. This output generates voltages of +32 VDC/10 mA and –12
VDC/0.3 A. The voltage of +32 VDC is generated at U51:REG and adjusted to
+32 VDC at R62. The voltage of –12 VDC is adjusted so as to achieve –12 VDC at
R57. When the current of 0.55 A or more runs through the –12 VDC line, the RT41
(Poly Switch) is activated to shut off the output.
L11,CR11,C14
L2
U11
REC
(SI 8120)
VOLTAGE
CONTROL
60kHz
R13-16
SS
Q11,C13
-SOFT
START
- Output
CONT
L21CR21,C24
L3
U21
REC
(SI 8015)
R28
VOLTAGE
CONTROL
125kHz
R32
SS
Q22
C23
L31,CR31,C38
L4
U31
REC
(SI 8010)
VOLTAGE
CONTROL
R47,47
ss
250kHz
Q31,C33
-SOFT
START
- Output
CONT
Fig. 7.2.14 Block Diagram of PWR (RF) board
TP3
+12V
R52,59
PR5V
L5
U12
IPk
U41
(MC34063AP1)
Vcc
COMP VOLTAGE
CONTROL
R57
TP4
HEATER H
HEATER V
JP21
HEATER OFF
TP5
+5V
PR5V
U22
7-19
7.2 Antenna Unit
U51
(uPC317HF)
CR52,C51
SW
Serise
REC
REG
R62
Q41(2SJ256)
TP6
CR41,C45
RT41
REC
J833
1. -12V
2,7,9,12. GND
3. +5V
4,5. +12V
6. +32V
8. HEATER VLT
8. HEATER OFF
10. HEATER H
+12V
TP7
+32V
-12V