Power Supply Circuits; Cpu Port Allocations; Voltage Lines (Main Unit); Pa Unit Voltage Lines - Icom IC-703 Service Manual

3-5 POWER SUPPLY CIRCUITS

3-5-1 VOLTAGE LINES (MAIN UNIT)

Line
Common 3 V converted from the HV line by the
H3V
+3 regulator circuit (IC9901).
Common 3 V converted from the 14V line by the
3V
+3 regulator circuit (IC9921).
Common 5 V converted from the 14V line by the
5V
+5 regulator circuit (IC9941).
The same voltage as the 5V line which is con-
trolled by the switching circuit (Q9964, Q9966).
P5V
The circuit is controlled by the "PSS" signal from
the CPU (IC5901, pin 90).
Common 8 V converted from the 14V line by the
8V
+8 regulator circuit (IC9961).
The same voltage as the 8V line which is con-
trolled by the switching circuit (Q9963, Q9965).
P8V
The circuit is controlled by the "PSS" signal from
the CPU (IC5901, pin 90).
Receive 8 V which is the same voltage as the 8V
line controlled by the switching circuit (Q6322,
R8V
Q6323) using the "RXS" signal from the CPU
(IC5901, pin 36).
Transmit 8 V which is the same voltage as the 8V
line controlled by the switching circuit (Q6342,
T8V
Q6343) using the "TXS" signal from the CPU
(IC5901, pin 35).

3-5-2 PA UNIT VOLTAGE LINES

Line
The voltage from a DC power supply.
HV
The same voltage as the HV line which is con-
trolled by the power switching circuit (Q80, Q81).
14V When the [POWER] switch is pushed, the CPU
outputs the "POWS" control signal to the power
switching circuit to turn the circuit ON.
3-5-3 VOLTAGE LINES (DISPLAY BOARD)
Line
Common 8 V line from the +8 regulator circuit
(MAIN unit; IC9961). The voltage is applied to the
8V
microphone via the J1, pin 1.
Common 5 V converted from the 5V line by the
+5 regulator circuit (IC5, Q10, Q11, D9). The out-
5V
put voltage is applied to the SUB-CPU (IC6),
LCD driver (IC2), etc.
Description
Description
Description

3-6 CPU PORT ALLOCATIONS

3-6-1 MAIN CPU PORT ALLOCATIONS
(MAIN UNIT; IC5901)
Pin Port
number name
1 BEEP
TONE
2
3 PDT
4 SNDK
5 PCK
8 2NOP
2NTH
9
16 TGK
18 PWRK
2N80
19
20 2N23
UNLK
21
22 TDAT
23 KDS
25 MINH
26 DPTK
27 LRXD
28 LTXD
31 SLOS
33 CTXD
34 CRXD
P2ST
39
3 - 9
Description
Outputs beep audio and CW side tone
signals.
Outputs CTCSS tone signal.
Outputs the serial data to the PLL IC
(IC9601).
Input port for transmitting signals from
the microphone or ACC connector.
Outputs the serial clock to the PLL IC
(IC9601).
Outputs control signal for the optional
2nd IF filter.
High : While the filter is selected.
Outputs control signal for the 2nd IF fil-
ter.
High : While the filter is bypassed.
Input port for the shock detecting sig-
nal.
Input port for the [POWER] swtich on
the front panel.
Low : While the [POWER]
pushed.
Outputs control signal for the 2nd IF fil-
ter.
High : While the 8 kHz filter is ON.
Outputs control signal for the 2nd IF fil-
ter.
High : While the 2.3 kHz filter is ON.
Input port for the PLL unlock signal.
Low : While the PLL is unlocked.
Outputs tuner data signal.
Outputs CW key down signal.
High : While transmitting on CW or
RTTY modes.
Output SSB modulation prohibitive sig-
nal.
High : While transmitting on CW, FM
or RTTY modes.
Input port for the PTT signal from the
data terminal (J6851, pin 3).
High : While data are transmitting.
Input port for the data signal from the
front unit.
Outputs data signal to the front unit.
Outputs LO level control signal.
Outputs CI-V signals.
Input port for the CI-V signals.
Outputs strobe signal to the PLL IC
(IC9601) for the 2nd LO signal.
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