Kch-11; Kch-11 Block Diagram - Kenwood TK-790 Service Manual

8-2. KCH-11

This display unit consists of a CPU (IC4) a reset IC (IC2),
5V AVR (IC1), EEPROM (IC3), and other components.
• Encoder
Channels are changed by the rotary encoder (ENC). The
up/down pulses from the rotary encoder enter the CPU
(IC4), and converted to a serial data signal, and are sent to
the control unit.
• Power supply
Power is supplied to the CPU by converting SB from the
control unit to 5V by IC1. And SB is supplied for the LED of
backlight.
• CPU
The on/off signals of keys other than the power switch,
and the PTT and HOOK signals, are converted to serial data
and sent to the control unit. Data is displayed on the 14-
digits and 3-digits dot matrix alphanumeric display.
LCD ASSY
Containing
LCD driver IC
ED1
SB
SW SW
KEY BACK LAMP
CIRCUIT DESCRIPTION
PTT
IC4
HK
78064GCXXX8EU
D13
Microprocessor
RX
D12
TX
IC3
AT24C64N10SI27 EEPROM
SW REF
SW SW SW SW SW
DM1 DM2
DM1 DM2
LCD BACK LAMP
Fig. 13 KCH-11 block diagram
TK-790/
• Dimmer function
From the control of the CPU's DM1/DM2 port, you can
switch the LCD/KEY backlight, busy/TX LED, or the optional
KMC-28 key backlight as shown in the following table.
Dimmer LCD
setting
H H
M M
L L
OFF OFF
5V
AVR
IC1
D19
RST
NJM78L05UA
RST
IC2
RH5VL42C
S5 S6 S7 S8
PF1 PF2 PF3 PF4
AF VR
S12 S13 S14 S15
PF7 SCN PF8 PF9
ENCODER
( B ) /H
KEY Busy/TX KMC-28
ON ON
ON ON
ON ON
OFF OFF
SB
S1
POWER
PS
RST
S9 S10 S11
PF5 MON PF6
S2 S3
MIC
1/2
TRD
RS1
RS2
( B )
ON
ON
ON
OFF
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