Icom IC-T81E Service Manual page 14

4-5-3 CPU (LOGIC UNIT; IC1)
Pin Port
number name
Input port for the over-voltage detec-
1 VIN tion from connected battery pack or
external power supply.
Input port for remote control signals
2 REMOTE from an optional HM-75A microphone
via the [MIC] jack.
3 SD Input port for the S-meter voltage.
Input port for CTCSS decoded sig-
4 CTCIN
nals.
5 LOCKV Input port for the PLL lock voltage.
Input port for the tranceiver's internal
6 THERMC
temparature.
Input port for the VCC voltage (con-
7 SBATT
nected battery voltage).
Outputs control signal for the LCD
8 CONT contrast.
High : The LCD contrast is deep.
Outputs CTCSS signals while trans-
9 CTCOUT
mitting.
Output port for:
• Beep audio signals while receiving.
10 BEEP • DTMF signals or 1750 Hz Europe
tone signal while transmitting.
Input port for the bias control voltage
to judge kinds of battery types.
11 BPCPI
High : Supply the bias control volt-
Input port for the noise signal (pulse-
12 NOISE type) from the IF IC (RF unit; IC 701,
pin 13).
Outputs data signals to the PLL IC2
(RF unit; IC802, pin 4).
13 PDA2/UL Input port for the PLL unlock signal
from the PLL IC2 (RF unit; IC802, pin
4).
Outputs data signals to the PLL IC1
(RF unit; IC801, pin 5).
14 PDA1/UL Input port for the PLL unlock signal
from the PLL IC1 (RF unit; IC801, pin
5).
Outputs strobe signals to the D/A IC
15 DAST
(LOGIC unit; IC5, pin2).
Outputs strobe signals to the I/O IC
16 IOST
(RF unit; IC2, pin 1 and IC3, pin 1).
Outputs strobe signals to the PLL IC2
17 PLST2
(RF unit, IC802, pin5).
Outputs strobe signals to the PLL IC1
18 PLST1
(RF unit, IC801, pin 3).
19 CLONEOUT Output port for the cloning signal.
Description
[EUR], [ITA], [UK]
age.
Pin Port
number name
20 CLONEIN
21 TXC
22 R3C
23 CPUHV
24 CHGC
25 AFON
26 PCON
27 TCON
28 BLED
29 LIGHT
30 MICC
31 RM/MM
32 POWER
33 RESET
39 PTT
41 CK
42 ESIO
43–46 KR3–KR0
47, 48 I1, I2
49–54 KS5–KS0
DICK,
55, 56
DIUK
4 - 7
Description
Input port for the cloning signal.
Outputs T4 regulator control signal.
High : While transmitting.
Outputs R3 regulator control signal.
High : While receiving.
Input port for the reset signal from
Q151 (LOGIC unit).
Outputs control signal for charger cir-
cuit (RF unit; Q5).
High : While battery is charging.
Outputs control signal for the AF
amplifier requlator circuit.
High : Activates the AF amplifier cir-
cuit.
Outputs +3C regulator control signal
(LOGIC unit; Q142 and Q145).
Outputs control signal for the Europe
tone and DTMF.
Low : Activates the Europe tone.
High : Activates DTMF.
Outputs BUSY LED control singal.
Low : The BUSY LED is ON.
Outputs LCD backlight control signal.
High : Lights ON.
Outputs control signal for the regulator
secton of MIC amplifier (LOGIC unit;
IC301).
Low : Activates the MIC amplifier
circuit.
Outputs AF mute and MIC mute con-
trol signals.
High : Mute is ON.
Input port for the [POWER] switch.
Input port for the RESET signal from
IC142, pin 1 (LOGIC unit).
Input port for the [PTT] switch.
Outputs clock signal to the PLL IC1
(IC801), PLL IC2 (IC802), D/A IC (IC5)
, I/O IC (IC2, IC3) on the RF unit and
EEPROM IC (LOGIC unit; IC2).
Data bus line for the EEPROM
(LOGIC unit; IC2).
Input ports for key matrix.
Input ports for Initial matrix.
Outputs port for key matrix.
Input port for the up/down signal from
the main dial (LOGIC unit; S1).