Power Supply Circuits; Port Allocations - Icom IC-4008A Service Manual

4-4 POWER SUPPLY CIRCUITS

VOLTAGE LINE
LINE
BATT The voltage from the connected battery pack.
Common 3 V converted from the BATT line at
the 3V regulator circuit (IC6). The circuit outputs
3V
the voltage regardless of the power ON/OFF
condition.
Common 3 V converted from the BATT line at
+3V
the +3V regulator circuit (Q25, D4).
Receive 3 V cotrolled by the R+3 regulator circuit
R+3
(Q18) using the "RXV" signal from CPU (IC1).
Transmit 3 V converted from the BATT line at the
T+3 T+3 regulator circuit (Q27, Q28, D5, etc.) using
the "TXV" signal coming from CPU (IC1).

4-5 PORT ALLOCATIONS

4-5-1 CPU (MAIN unit; IC1)
Pin Port
number name
Input port for the PTT switch from the
31 PTT2 external mic jack (MAIN unit; J1).
Low : External PTT switch is ON.
Input port for the internal PTT switch.
34 PTT1
Low : While PTT switch is pushed.
Input port for the [DOWN] switch.
35 DOWN
Input port for the [UP] switch.
36 UP
Input port for the [MODE] switch.
37 MODE
Input port for the POWER switch.
Low : While POWER switch is
38 POWSW
Input port for PLL unlock signal from
the PLL IC (RF unit; IC1).
45 UNLK
Low : During unlock.
Outputs beep audio signal.
46 BEEP
Outputs volume mute switch (Q23)
48 RMUTE control signal.
High : While squelched
Outputs control signal for the AF ampli-
49 AFON
fier regulator circuit (Q5, Q10, Q11).
High: When squelch is open.
Outputs clock signal to the PLL IC (RF
50 PLLCK
unit; IC1).
DESCRIPTION
Description
pushed.
Pin Port
number name
51 PLLDA
52 PLLST
53 POWER
CTCO0–
54–56
CTCO2
57 TXMOD
58 CTCIN
59 SQLIN
60 REMIN
61 BATIN
62 SENIN
73 EEPCK
74 EEPDA
75 PSC
76 RXV
77 TXV
78 LAMPC
79 MICSW
80 MMUTE
4 - 3
Description
Outputs data signals to the PLL IC (RF
unit; IC1).
Outputs strobe signals for the PLL IC
(RF unit; IC1).
Outputs control signal for the +3V reg-
ulator circuit (MAIN unit; Q25, D4).
Output port for the CTCSS signals.
Outputs control signal for the MIC
amplifier (IC2).
Low : While microphone amplifier is
ON.
Input port for the CTCSS decode sig-
nals.
Input port for squelch level signal.
Input ports for the control signal from
the external remote microphone.
Input port form the connected battery
pack for low battery indication.
Input port for the RSSI signal from the
FM IF IC (RF unit; IC2) to detect receiv-
ing signal strength level.
Outputs clock signal to the EEPROM
(IC3).
Outputs data signals to the EEPROM
(IC3).
Output port for power save function,
applied to VCO regurator circuit (RF
unit; Q13, Q14, D8, D9).
Outputs the R+3 regulator control sig-
nal (Q18).
Outputs the T+3 regulator control sig-
nal (Q27, Q28, D5, etc.).
Outputs control signal for LCD back-
light.
Low : While LCD backlight is ON.
Outputs internal microphone control
signal.
High : While internal PTT switch is
pushed.
Outputs MIC mute signal for RING
function.
High : While RING signals are out-
put, etc.