Components Description - Kenwood TH-K40A Service Manual

TX-RX unit (X57-822X-XX)
Ref. No. Use/Function
IC1 PLL system
IC200 FM IF system
IC300 D/A converter
IC301 OP AMP
IC302 OP AMP
IC303 OP AMP
IC304 OP AMP
Voltage
IC305
detector/3.3V
Voltage
IC306
regulator/5.0V
AF power ampli-
IC307
fi er
Voltage
IC308
regulator/5.0V
IC400 EEPROM
IC401 MCU
VCO shift control
Q1
switch
Q2 Ripple fi lter
Q3 Oscillator
Q4 Buffer amplifi er
Q5 RF amplifi er
Q6 Logic invert
Power supply
Q7
(3.0V)
Q101 Pre drive amplifi er
Q102 Drive amplifi er
Q103 Final amplifi er
Voltage dis-
Q104
charge switch
Wide/Narrow
Q200
switch
Q201 Doubler
Q202 1st IF amplifi er
Q203 1st mixer
Q204 RF amplifi er
Power supply
Q300
(5.0V) switch
SP mute control
Q301
switch
SP mute control
Q302
switch
Speaker mute
Q303
switch

COMPONENTS DESCRIPTION

Operation/Condition/Compatibility
Frequency control
2nd mixer, IF amplifi er, FM
detector
AF mute/MOD level and fre-
quency adjust
2.5V reference voltage/MIC
amplifi er
Detect AF fi lter
CTCSS/DCS fi lter
MIC amplifi er/IDC
MCU reset
5M/5MS power supply
Speaker output
5C/5T/5R power supply
Tuning data/Memory data
TX: ON
for VCO power supply
TX/RX VCO
for VCO output
for VCO output
for unlock signal
for PLL IC
5.0W RF power
for FET bias voltage.
Active ON (VDCSW: H)
for ceramic fi lter selector
Wide: ON (W/L: L)
2nd Lo: 38.4MHz
1st IF: 38.85MHz
RX 1st amplifi re
Active ON (5VC: L)
Active ON (SM: H)
for pop-noise Active ON
for AF signal line Active ON
TH-K40A/K40E
Ref. No. Use/Function
Power supply
Q304
(5MS) switch
Speaker mute
Q305
switch
IC power supply
Q306
switch
Power supply
Q307
(5R) switch
Power supply
Q308
(5T) switch
Q400 Beat shift switch
Backlight LED
Q401
switch
Backlight control
Q402
switch
Q403 Busy LED switch
Q404 TX LED switch
VCO frequency
D1,D2
control
D3 RF switch
D4 VCO modulation
Assist frequency
D5
control
D6 Speed up
D7 RF switch
D8 RF switch
D9, D10 Speed up
D11 Speed up
D101-104 Antenna switch
Band-pass fi lter
D200-204
tuning
D300 VOX signal detect
Reverse connec-
D301
tion protection
Reverse current
D302
prevention
Reverse current
D304
prevention
D305 Surge protection
Over voltage limit-
D401
ter
Reverse current
D404-412
prevention
LCD backlight
D414, D415
LED
Key backlight
D416-425
LED
D426 Busy LED
D427 TX LED
Operation/Condition/Compatibility
Active ON (5MSC: L)
for AF signal line Active ON
for AF power IC Active ON
Active ON (5RC: L)
Active ON (5TC: L)
Active ON (BSFT: H)
Active ON
Active ON (LAMP: H)
Active ON (LEDG: H)
Active ON (LEDR: H)
for frequency range change
TX: ON
for frequency modulation
for ripple fi lter
for TX signal TX: ON
for RX signal
for ripple fi lter
for VCO shift control line
TX: ON
UHF band for receiver
Battry terminal
for IC306 input
for IC308 input
Mic line
3.6V zener diode
Key matrix
Busy: light
TX: light
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