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Input port for the PLL unlock signal from
the PLL IC (RF unit; IC2).
Low : During unlock.
Input port for the PTT switch from the
external mic jack (MAIN unit; J303).
Low : External PTT switch is ON.
Input port for the control signal from the
external remote microphone.
Input port for the transceiver’s internal
temperature.
Input port for the squelch level signal.
Input port for connected battery pack
voltage.
Input port for the [MODE] switch.
Input port for the [POWER] switch.
Low : While the [POWER] switch is
pushed.
Outputs beep audio signal.
Input port for the [DOWN] switch.
Input port for the [UP] switch.
Input port for the internal [PTT] switch.
Low : While the [PTT] switch is
pushed.
Outputs the control signal of LCD back
light.
Outputs the control signal of the AF
amplifier regulator circuit (MAIN unit;
Q306, Q307, Q311).
Outputs the control signal of the R+3
regulator circuit (MAIN unit; Q304).
Outputs the [MIC] mute signal for RING
function.
High : While RING signals are out-
put, etc.
Outputs internal microphone control
signal.
High : While the internal PTT switch
is pushed.
Outputs the control signal of the +3V
regulator circuit (MAIN unit; Q303,
D301).
Outputs the control signal of the vol-
ume mute switch (MAIN unit; Q316).
High : While squelched.
Outputs the control signal of the T+3
regulator circuit (Q305, Q308, D303,
D304).
Outputs the control signal of the charge
circuit (Q312, Q314, D305, D308).
Input port for the test mode switch.
Outputs the clock signal to the EEP-
ROM (MAIN unit; IC300).
Outputs data signals to the EEPROM
(MAIN unit; IC300).
Input port for the control signal of the
tone detection
Outputs the shift control signal to the
PLL IC (RF unit; IC2).
Outputs strobe signals for the PLL IC
(RF unit; IC2).
Outputs the clock signal to the PLL IC
(RF unit; IC2).
Outputs data signals to the PLL IC (RF
unit; IC2).
27
31
32
33
35
36
37
38
TEST
EEPCK
EEPDA
DETOUT
SHIFT
PLSTB
CK
DATA
Pin
Port
Description
number
name
Outputs deviation control signal.
Outputs TX power control signal.
Outputs PLL reference frequency con-
trol signal.
4 - 3
LINE
VCC
CPU3V
+3V
R+3
T+3
DESCRIPTION
The voltage from the connected battery or
power supply from DC IN (J302).
Common 3 V converted from the VCC line at the
3V regulator circuit (IC303). The circuit outputs
the voltage regardless of the power ON/OFF
condition.
Common 3 V converted from the VCC line at the
+3V regulator circuit (Q303, D301).
Receive 3 V cotrolled by the R+3 regulator cir-
cuit (Q304) using the “RXV” signal from the CPU
(IC301).
Transmit 3 V converted from the VCC line at the
T+3 regulator circuit (Q305, Q308, D303, D304)
using the “TXV” signal coming from the CPU
(IC301).
UNLK
PTT
MICIN
TEMP
SQLIN
VIN
MODE
POWSW
BEEP
DOWN
UP
PTTSW
LAMPO
AFON
RXV
MMUTE
MICSW
POWER
RMUTE
TXV
CHGC
Pin
Port
Description
number
name
4-4 POWER SUPPLY CIRCUITS
VOLTAGE LINE
4-5 PORT ALLOCATIONS
4-5-1 D/A CONVERTER (RF unit; IC3)
1
2
3
MODC
PWRC
FC
Pin
Port
Description
number
name
4-5-2 CPU (MAIN unit; IC1)
41
42
43
44
46
47
51
52
53
54
55
56
57
58
59
61
62
63
64
65
66
Summary of Contents for IC-4088E
Page 1: ...SERVICE MANUAL LPD FM TRANSCEIVER ...
Page 2: ......
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Page 29: ...1 1 32 Kamiminami Hirano ku Osaka 547 0003 Japan S 13910IZ C1 2002 Icom Inc ...