Kenwood TK-7160 Service Manual page 15

Control Circuit
The CPU carries out the following tasks:
1) Controls the WIDE, NARROW, TX/RX outputs.
2) Controls the AQUA IC (IC241).
3) Controls the PLL (IC401).
4) Controls the D/A converter (IC201) and adjusts the vol-
ume, modulation and transmission power.
CK
DT
LD
IC101
CPU
PLLE
Fig. 10 Control circuit
■ Memory Circuit
The transceiver has an 64k-bit EEPROM (IC81). The
EEPROM contains adjustment data. The CPU (IC101) con-
trols the EEPROM through three serial data lines.
EEPCK
EEPDT
IC101
CPU
EEPWP
Fig. 11 Memory circuit
■ Display Circuit
The CPU (IC101) controls the display LCD and LEDs.
When power is on, the CPU will use the MBL line to control
the LCD illumination and key backlight LEDs.
The dimmer function is controlled by the switch Q1. The
LCD controller (IC1) controls the functions of the LCD
through the DO, CE, CL, DI lines from the CPU.
CE
CL
IC1
IC101
DI LCD
CPU
BRI
driver
DO
Fig. 12 Display circuit
CIRCUIT DESCRIPTION
IC201
D/A
converter
IC401
PLL
IC81
EEPROM
Q1
SW
BL
Q4 Q2
SW SW
D7~D18
LCD
illumination
Q3
SW
D1~D6
Key backlit
■ Key Matrix Circuit
The TK-7160 front panel has function keys. Each of them
is connected to a cross point of a matrix of the KMI1 to KMO3
ports of the IC1 LCD driver. The KMO1 to KMO3 ports are
always high, while the KMI1 to KMI3 ports are always low.
The microprocessor monitors the status of the KMI1 to
KMO3 ports. If the state of one of the ports changes, the
microprocessor assumes that the key at the matrix point cor-
responding to that port has been pressed.
KMI1
KMI2
KMI3
IC1
LCD
KMO3
driver
KMO2
KMO1
Fig. 13 Key matrix circuit
■ Encode
The QT and DQT signals are output from QT/DQT of the
CPU (IC101) and summed with the external pin DI line by the
AQUA IC (IC241) and the resulting signal goes to the D/A con-
verter (IC201). The DTMF signal is output from DTMF of the
CPU and goes to the D/A converter (IC201). The signal is
summed with a MIC signal by the AQUA IC (IC241), and the
resulting signal goes to the D/A converter (IC201).
The D/A converter (IC201) adjusts the MO level and the
balance between the MO and QT/DQT levels. Part of a QT/
DQT signal is summed with MO and the resulting signal goes
to the VCOMOD pin of the VCO. This signal is applied to a
varicap diode in the VCO for direct FM modulation.
IC241
QT/DQT
AQUA
IC
IC101
DI
CPU
IC241
DTMF
IC201
AQUA
D/A
IC
Fig. 14 Encode
TK-7160
VOL CH
UP A
UP
VOL CH
DN DN <B
C>
S
TCXO
MOD
X401 IC401
TCXO PLL
IC201
VCO
D/A
VCO
MOD
HT
15