Other Circuits - Icom IC-R100 Service Manual

4-4-2 5VAND 10V REGULATOR CIRCUITS
(MAIN UNIT) |
The ОС voltages are supplied from regulator circuits
corresponding to the voltages. They are regulated at
the follovving circuits using 13.8V DC.
(1) 5 V REGULATOR (MAIN UNIT)
5V DC is regulated by the three-terminal voltage regulator
(IC9) and applied to the MAIN and PLL UNITS.
(2) 10 V REGULATOR (MAIN UNIT)
10V DC is regulated by the three-terminal voltage regulator
(IC8) and applied to the MAIN and PLL UNITS.
e 5 V AND 10 V REGULATOR CIRCUITS
HV iine
[PUSH-ON/VOL]
CONTROL
POW
line
13.8 V
Fig. 9
4-4-3 CPU POWER SUPPLY CIRCUIT
(LOGIC UNIT)
The DC voltage is applied to the main CPU (IC2, pin 8) via
D2 from the lithium backup battery (BT1) to provide
backup for the memory contents regardless of the power
switch condition.
e CPU POWER SUPPLY AND CPU RESET CIRCUITS
LOG 5 line
Fig. 10
4-4-4 SUB CPU POWER SUPPLY CIRCUIT
(MAIN AND LOGIC UNITS)
The DC voltage is applied to the sub CPU (IC1, pin 54)
from the lithium backup battery (BT1) to provide backup
for the memory contents. This circuit is controlled by
Q28.
* SUB CPU POWER SUPPLY
LOG 5 line
SBUP line
to
LOGIC UNIT
IC1 (pin 54)
Fig. 11
4-5 OTHER CIRCUITS
4-5-1 DIMMER CIRCUIT (LOGIC UNIT)
The dimmer circuit consists of Q8, Q9 and other
components and drives backlights (DS2), ensuring that
brightness does not change even with a change of
power supply.
When the main CPU (IC2, pin 28) changes its output
level, Q8 and Q9 change the base voltage and collector
current.
When the main CPU (IC2, pin 28) outputs "LOW", the
base of Q9 obtains 5V through R89 to light up DS2.
When the main CPU (IC2, pin 28) outputs "HIGH" to turn
ON, Q1, R89 and R90 divide 5 V into three voltages. The
three voltage portions are applied to the base of Q9.
Therefore, the collector voltage from Q8 decreases to
dim the brightness of the lamp (DS2).
4-5-2 CPU RESET CIRCUIT (LOGIC UNIT)
When the power switch is turned OFF, the reset circuit
functions as a three-terminal voltage regulator IC (IC3)
which resets the main CPU (IC2) IC3 detects +5 V
when the DC voltage is applied to the input terminal
of IC3 and outputs 5 V. The voltage of the leading
edge is applied to a time constant (C55, R93) to obtain
sufficient reset time and inverted to supply a reset
signal to the main CPU (IC2, pin 7) at Q12.
The differential circuit (C54, R84) functions while an AND
circuit (D3 , D5) pushes and holds the [CLK], [FUNC],
and [ENT] switches. When the power switch is turned
ON, the differential circuit outputs a pulse to reset CPU.
4-5-3 REAL TIME CLOCK (LOGIC UNIT)
This receiver has a clock IC (IC1) with timer function.
A 32.768 kHz is oscillated at X2 for clock reference.
When the power switch is turned OFF, the DC voltage is
applied to the sub CPU (IC1) from the lithium battery to
provide backup for clock operation.