Power Supply Circuits - Icom ic-r20 Service Manual

4-4 POWER SUPPLY CIRCUITS

4-4-1 LOGIC UNIT VOLTAGE LINES
Line
The voltage is same as connected battery pack.
The voltage is supplied to the charge controller
VCC
(Q32).
Common 3 V converted from the VCC line or
external DC power supply by the +3 regulator
(IC8, pins 1 and 5). The output voltage is sup-
CPU3V
plied to the main CPU (IC3), reset IC (IC2), EEP-
ROM (IC1), etc.
Common 3 V converted from the CPU3V line by
the +3 regulator (Q13 and Q14). The regulator is
controlled by the +3SC line from the main CPU
+3S
(IC3, pin 40). The output voltage is supplied to
the electronics volume (IC7), pre-amplifiers (Q12
and Q16), etc.
Common 3 V converted from the CPU3V line by
the +3 regulator circuit (Q17). The output voltage
+3V
is supplied to the CI-V interface circuit (IC4, Q3
and Q6), etc.
Receive 3 V converted from the VCC line or
external DC power supply by the +3 regulators
(IC9, pins 1 and 5; Q10). The regulator is con-
A_R3
trolled by the A_R3C line from the main CPU
(IC3, pin 67). The output voltage is supplied to
the RF unit, etc.
Receive 3 V converted from the VCC line or
external DC power supply by the +3 regulators
(IC9, pins 1 and 5; Q15). The regulator is con-
B_R3
trolled by the B_R3C line from the main CPU
(IC3, pin 75). The output voltage is supplied to
the RF unit, etc.
4-4-2 REC UNIT VOLTAGE LINES
Line
Common 3 V from the LOGIC unit via the J7, pin
1, and is then supplied to the SUB_3V regulator
+3V
(Q2). The regulator is controlled by SUB_3C line
from the sub CPU (IC2, pin 45).
Common 3 V converted from +3V line by the
SUB_3V regulator (Q2). The output voltage is
SUB_3V
supplied to the sub CPU (IC2), memory (IC6),
RECORDING IC (IC7), etc.
4-4-2 REC UNIT VOLTAGE LINES
Line
Common 3 V from the LOGIC unit via the J7, pin
1, and is then supplied to the SUB_3V regulator
+3V
(Q2). The regulator is controlled by SUB_3C line
from the sub CPU (IC2, pin 45).
Common 3 V converted from +3V line by the
SUB_3V regulator (Q2). The output voltage is
SUB_3V
supplied to the sub CPU (IC2), memory (IC6),
RECORDING IC (IC7), etc.
Description
Description
Description
4-4-3 RF UNIT VOLTAGE LINES
Line
Receive 3 V line from the LOGIC unit via the J1,
pin 37. The voltage is supplied to the RF (IC19),
A_R3V
IF (Q5) and LO (Q540) amplifiers, 1st (IC1) and
2nd (IC10) mixers, regulators, etc.
Receive 3 V line from the LOGIC unit via the J1,
pin 22. The voltage is supplied to the RF (IC18),
B_R3V
IF (Q542) and LO (Q555) amplifiers, 1st (IC15)
and 2nd (IC16) mixers, regulators, etc.
Receive 3 V converted from the A_R3V line by
the +3 regulator (Q509). The regulator is con-
HF3V
trolled by the HFC line from the main CPU
(LOGIC unit; IC3, pin 46).
Common 3 V converted from the A_R3V line by
the +3 regulator (Q527). The regulator is con-
NB3V
trolled by the NBC line from the D/A converter
(IC22, pin 13).
Receive 3 V converted from the A_R3V line by
the +3 regulator (Q501). The regulator is con-
300M3V
trolled by the A_300MC line from the expander
IC (IC14, pin 3).
Receive 3 V converted from the A_R3V line by
the +3 regulator (Q502). The regulator is con-
A_VHF3V
trolled by the A_VHFC line from the expander IC
(IC14, pin 2).
Receive 3 V converted from the A_R3V line by
the +3 regulator (Q502). The regulator is con-
A_UHF3V
trolled by the A_UHFC line from the expander IC
(IC14, pin 4).
Receive 3 V converted from the B_R3V line by
the +3 regulator (Q554). The regulator is con-
B_VHF3V
trolled by the B_VHFC line from the expander IC
(IC20, pin 2).
Receive 3 V converted from the B_R3V line by
the +3 regulator (Q554). The regulator is con-
B_UHF3V
trolled by the B_UHFC line from the expander IC
(IC20, pin 3).
Receive 3 V converted from the B_R3V line by
the +3 regulator (Q503). The regulator is con-
B_G3V
trolled by the B_GC line from the expander IC
(IC20, pin 4).
Receive 3 V converted from the B_R3V line by
the +3 regulator (Q503). The regulator is con-
B_800M3V
trolled by the B_800MC line from the expander
IC (IC20, pin 5).
Receive 3 V converted from the B_R3V line by
the +3 regulator (Q546). The regulator is con-
B_AM3V
trolled by the B_AMC line from the expander IC
(IC20, pin 18).
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Description