Power Supply Circuits; Port Allocations - Icom IC-A110 Service Manual

3-4 POWER SUPPLY CIRCUITS

VOLTAGE LINES (MAIN UNIT)
LINE
The voltage from the external DC power con-
VCC nector which is controlled by the power switch
([VOL] control).
Common 8 V converted from the VCC line by the
+8 V regulator circuit (IC29). The output voltage
8V
is applied to the +5 V regulator circuit (IC7), the
ripple filter (Q16), and etc.
Common 5 V converted from the 8V line by the
+5V regulator (IC7) and +5V current amplifier
+5V (Q22, Q23, D15) circuits. The output voltage is
applied to the electric volume IC (IC13), buffer
amplifiers (Q68, Q69), and etc.
Common 5 V converted from the VCC line by +8
V regulator (Q82, D35) and +5 V regulator cir-
CPU5V
cuits (IC26). The output 5 V voltage is applied to
the CPU (FRONT unit; IC1).
8 V for transmitter circuits regulated by the +8 V
T8
regulator circuit (IC29).
8 V for receiver circuits regulated by the +8 V
R8
regulator circuit (IC29).
DESCRIPTION

3-5 PORT ALLOCATIONS

3-5-1 OUTPUT EXPANDER IC (FRONT unit: IC5)
Pin Port
number name
LED1,
4, 5
LED2
6 TRC
7 R/T
11 SMUT
12 AFMUT
13 RMUT
14 TMUT
3 - 5
Description
Outputs backlight control signals.
LED1 LED2 Backlight condition
Low Low Light OFF
High Low No establishment
Low High Light ON, Dimmer ON
High High Light ON, Dimmer OFF
Outputs control signal to the MOD/AF
swtich (MAIN unit: IC48, pin 5) and
etc.
High: While transmitting.
Outputs control signal to the TX/RX
switch (MAIN unit: Q58, pin 1) for
VCO.
Low: While transmitting.
Outputs AF mute swtich (MAIN unit:
IC30, Q86, Q75, Q74, D43) control
signal.
Low: While squelched.
Outputs control signal to the mute
switch (MAIN unit; Q100, Q101, D66)
for speaker amplifier, and etc.
Low: While the speaker output is
muted.
Outputs RMUTE switch (IC6) control
signal.
Low: While squelched.
Outputs T8 regulator control signal.
Low: When TX is muted.