Kenwood TH-K4AT Service Manual page 16

TH-K4AT/K4E
Ref. No. Use/Function
Q33 operation
Q34
switch
Q35 DC IN detection H: DC IN detection
Ni-MH temperature
Q36
detection
AF amplifier/
Q37
Lamp AVR
Q37 operation On when the speaker outputs the audio
Q38
switch
Q41 5MS switch
TX/BUSY LED
Q47
switch
Q50 Key LED switch On when the key LED lights
LCD LED
Q51
switch
Beat shift
Q52
switch
Q53 5R/5MV switch On when 5R or 5MV is applied
Q55 5T switch
Speaker mute
Q56
switch
Q57 5C switch
Q12 gate
Q58
voltage switch
VCO frequency
D1-4
control
D5 Frequency shift
D6 VCO modulation
D7 Speed up
D8 RF switch
D9 RF switch
D10-13 Antenna switch On TX
Reverse current
D14
prevention
APC output
D15
voltage limiter
D16 PLL lock detection
D18-21 RX BPF tuning
MIC mute
D22
control
VOX detection
D24
rectification
Speaker mute
D25
speed up
D26 C246 discharge
MIC ALC
D27
rectification
Reverse current
D30
prevention
Constant-current
D31
circuit
Reverse current
D32
prevention
Reverse current
D33
prevention
16
COMPONENTS DESCRIPTION
Operation/Condition/Compatibility
On when charging
On when temperature detection is activated
or lamp lights
On when 5MS is applied
On when the LCD LED lights
On when 5T is applied
On when 5C is applied
Off when High power is selected
Ripple filter
On TX
On RX
APC reference voltage
Charge current
Constant-current charge
DC IN
Battery
Ref. No. Use/Function Operation/Condition/Compatibility
AVR
D34
constant-voltage
Reverse current
D35 Battery
prevention
Reverse current
D36 DC IN
prevention
D40 TX LED Lights on TX
D41 BUSY LED Lights on RX
D42-44 Key illumination
Key backlight illumination
D46,47 LED
LCD illumination
D48,49 LCD backlight illumination
LED
Key type
D60
detection
UHF type
D61
detection
market code
D62-65
detection
Reverse current
D69-72 Key matrix
prevention
D73 Voltage drop
Over input
D74
protection
D79,80 Limiter
Reverse current
D81
prevention