Kenwood TK-782 Service Manual page 40

Control Circuit
The CPU carries out the following tasks:
1) Controls the shift register (IC7, IC8, IC508) AF MUTE,
WIDE/NARROW, T/R KEY outputs.
2) Adjusts the AF signal level of the audio processor (IC504)
and turns the filter select compounder on or off.
3) Controls the DTMF decoder (IC507).
4) Controls the LCD assembly display data.
5) Controls the PLL (IC300).
6) Controls the D/A converter (IC5) and adjusts the volume,
modulation and transmission power.
LCD ASSY
IC508
Shift
register
IC504
IC511
Audio
CPU
processor AFCLR
AFMSKE
AFDAT
AFRDT
AFTRD
AFRTM
AFSTB
IC507
DTMF
DECO.
Fig. 9 Control circuit /
CIRCUIT DESCRIPTION /
TX-RX UNIT (A/2)
IC8
Shift
register
DT
IC7
RFCK
Shift
ES
register
EN
IC5
D/A
converter
IC300
PLL
" Memory Circuit
The transceiver has a 2M-bit (256k x 8) flash ROM (IC510)
and an 16k-bit EEPROM (IC512). The flash ROM contains
firmware programs, data and user data which is programmed
with the FPU. The EEPROM contains adjustment data. The
CPU (IC511) controls the flash ROM through an external ad-
dress bus and an external data bus. The CPU controls the
EEPROM through two serial data lines.
"
ADDRESS BUS
IC510
FLASH
ROM
DATA BUS
Fig. 10 Momory circuit /
" Display Circuit
The CPU (IC511) controls the shift register (IC508) and dis-
play LEDs. When the LG line goes high when the transceiver
is busy, Q508 turns on and the green LED on D511 lights. In
transmit mode, the LR line goes high, Q509 turns on and the
red light lights. Backlighting LEDs for the key operation unit
(D512~D517) and LCD are provided.
When the KBLC line goes high, Q512 turns on, then Q513
turns on, and the key illumination LED lights. A voltage is
applied to the LEDA line to turn on the LCD backlight.
"
KBLC
Q512
SW
IC508
LG
Q508
Shift
SW
register
LR
Q509
SW
Fig. 11 Display circuit /
TK-782
SCL
IC511 IC512
SDA
CPU
EEPROM
LEDA
Q513
SW
D512~517
D511
GRN
RED
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