Power Supply Circuit - Kenwood TK-7360 Service Manual

■ High-speed data (2-tone)
The demodulated signal from the FM IC (IC500) is ampli-
fied by the baseband IC and passes through a band pass
fi lter and a comparator (IC709) to detect the signal to the
MCU. The MCU digitizes this signal and decodes the signal
after receiving the signal at pin 5 (HSDI).
■ MSK/ DTMF
The demodulated signal from the FM IC (IC500) will in-
put to the baseband IC (IC702), then the baseband IC will
decode and send the decoded information to the MCU by
the data line.
The MCU then processes the decoded information.
IC702
Baseband IC
IC500
FM IC
DTMF/MSK
decode
IC709
BPF/COMP
Fig. 15 Decode
CIRCUIT DESCRIPTION
REPLAY data
DTMF/MSK
decode data
LSDI
IC704
MCU
QT/DQT
HSDI
2-TONE
SB
Q714
IGN
SW
SBC
5M
BATT
POWER
3.3M
IC704
MCU
POWER
SW
Fig. 16 Power supply circuit
TK-7360/7360H/7360H

7. Power Supply Circuit

When the power switch on the display unit is pressed,
the power port on the display unit which is connected to
port 17 (POWER), goes low, then port 52 (SBC) goes high,
Q406 turns on, SB switch (Q407) turns on and power (SB) is
supplied to the transceiver.
When the DC power is supplied to the transceiver, volt-
age regulator IC (IC401, IC402) will supply into the MCU
VDD and reset the voltage detect IC (IC404). IC404 will
generate signal (RESET) into the reset terminal on the MCU
(IC704) to carry out a power on reset. Also, MCU (IC704) is
checking on port 91 (BATT). If DC power is less than about
8.5V, the transceiver is unable to power on.
When the DC power voltage deceases from normal volt-
age, the INT voltage detector IC (IC403) will set to high on
MCU port 18 (INT). If B line becomes less than about 8.5V,
MCU will send the backup data to EEPROM (IC705) and go
into STOP mode.
This circuit has an overvoltage protection circuit. If a DC
voltage of 16V or higher is applied to the base of Q717, this
voltage turns Q717 on and sets port 18 (INT) to low. As a re-
sult port 78 (SBC) is low, and turns Q406 and Q407 (SB) off.
Q407
SW
Q406
SW
IC402
AVR
D715
IC401 Q717
AVR SW
IC404
V-DET
IC403
V-DET
B
V
( )
17