Control Circuit; Memory Circuit; Display Circuit - Kenwood TK-7108 Service Manual

Control Circuit

The CPU carries out the following tasks:
1) Controls the WIDE, NARROW, TX/RX outputs.
2) Adjusts the AF signal level of the AF filter (IC251) and
turns the filter select compounder on or off.
3) Controls the display unit.
4) Controls the PLL (IC401).
5) Controls the D/A converter (IC161) and adjusts the vol-
ume, modulation and transmission power.

■ Memory Circuit

The transceiver has a 64k-bit EEPROM (IC66). The
EEPROM contains adjustment data. The CPU (IC101) con-
trols the EEPROM through three serial data lines.
CK
DT
LD
IC101
CPU
PLLE
Fig. 10 Control circuit /

■ Display Circuit

The shift register controls the display LEDs through the CL
and DI lines from the CPU (IC101).
When the transceiver is busy, LED G line becomes high
impedance, turning on Q4 and the green LED (D11) lights, in
transmit mode, the LED R line becomes low impedance, and
the red LED (D12) lights.
Backlit LEDs (D1~D4) are provided and will only goes off
when MBL line becomes low impedance.
When a function key (MON, PF, C1, C2, C3 or C4) is se-
lected, its respective line becomes low impedance (LED
MON, LED PF, LED C1, LED C2, LED C3 or LED C4), the
amber LED lights.
CIRCUIT DESCRIPTION /
IC161
D/A
converter
IC401
PLL
!
NM
CL
IC101
CPU
DI
IC1
Shift
register
Fig. 12 Display circuit /
!
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`mr
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NF
OF ^c =Ef`ORNF= ^c
!"#
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PF
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QF
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RF L
!"#
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`mr=Ef`NMNF=
IC101
CPU
Fig. 11 Memory circuit /
!"#
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iba
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!"iba
`P iba=`QF
LED MON
D5
LED PF D6
LED C1 D7
LED C2 D8
LED C3 D9
LED C4 D10
LED R D12
LED G D11
Q4
SW
D1~D4
MICBL
Q10 Q9
SW SW
!
NO
TK-7108
!
!"
!"#$%&'()*
!"#$ %&'()*+
!"#$%&bbmolj
EEPCK
EEPDT
IC66
EEPROM
EEPWP
!"
NN
!"`i af
!"#$ %&nQ
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!" #$%&'
!"
iba
!
29