Kenwood TKR-D710 Service Manual page 19

SPO
INT_SP
SPI
SPO
EXT_SP
RD
RD
RA
TD
TA
MIC
DSP
Fig. 16 Modulation circuit (Analog/Digital signal processing)
5. Display unit
The Display unit (X54-4060-20) is different from X54-
3580-20 which is used in the TKR-750/850/751/851.
The Display unit (X54-4060-20) consists of the following
circuits:
(1) LED circuit
(2) Key switch circuit
(3) Power supply voltage detector
5-1. LED circuit
The display circuit consists of various types of LEDs:
7-segment type D506 and D507 (red), D503 (red: transmis-
sion), D504 (green: busy), D505 (green: power on).
IC502 to IC505 are shift registers that convert MCU se-
rial data to parallel data and turn on the LEDs.
CIRCUIT DESCRIPTION
AMP_B
AMP_SW
SW
Audio_AMP
IC402
IC501
MICADC0
MICADC1
MODDAC
MCU
SPDAC
IC20
PWM1
IFR
IC6
ADC1
Squelch DAC
IC14
DAC
IC412
DAC
IC412
DAC
IC412
IC405
(C/4)
IC404(A/2)
LPF
LPF
CR-LPF
LPF DET
LPF
5-2. Key switch circuit
There are PF key 1 to PF key 6 on the Display unit. Using
these key switches, mode settings are available.
The logic signals pushing these key switches are entered
directly into the MCU (IC20).
5-3. Power supply voltage detector
The Display unit has a power supply voltage detector cir-
cuit.
The power supply voltage (SB) is divided through two
resistors (R545 and R546).
The divided voltage is input to the MCU via the IC508.
TKR-D710
IC404
(B/2)
MOD
MOD
IF
signal
19