Kenwood TK-780 Service Manual Supplement page 36

TK-780/H
Ref. No. Use / Function
D36 Temperature protection
D37 Reverse protection
D206~208 Front tune
D209,210 Usable temperature
range
D211 ANT swtich
D212 ANT switch
D213 Over voltage
protection
TX-RX Unit (X57-6480-XX) (B/2)
-10 : K -11 : K2 -12 : HK -13 : HK2
Ref. No. Use / Function
IC501 LPF, amplification
IC502 Amplification
IC503 Base voltage/
Buffer amp
IC504 Audio processor
IC506 Analog switch
IC507 DTMF decoder
IC508 Shift register
IC509 Reset
IC510 Flash ROM
IC511 CPU
IC512 EEPROM
IC513 5V AVR
IC710 Buffer amp
IC711 Buffer amp
Q501 MIC mute
Q502 AF mute
Q503 Noise amp
Q507 Inverter
Q508 LED switch
Q509 LED switch
Q510 Clock switch shift
Q511 FSW swtich
Q512 Key backlight switch
Q513 Key backlight switch
Q515 Key backlight switch
36
DESCRIPTION OF COMPONENTS
Operation / Condition
TX time on
Operation / Condition
LSD
AF, HSD
ASQ
Compander, MIC amplifier, ALC,
Modem, AF filter, IDC
MO, DEO, EMG, MI switch
DTMF detection
LR, LG, KBLC, MM1, T/R, KEY,
BSFT, PA2 output
Power on time "L" output
5C (TX-RX unit B/2)
HSD
MIC
MM "H" and MM1 "H" time mute on
KEY "H" time mute on
PA2 H/L switch
LG "H" time on, Busy time green on
LR "H" time on, TX time red on
BSFT "H" time clock shift on
FSW "L" time foot switch on
KBLC "H" time on
KBLC "H" time key backlight on
Ref. No. Use / Function
D501 Surge absorption
D502 Over current
protection
D503 Surge absorption
D504 Surge absorption
D505 Surge absorption
D507 OR gate (MIC mute)
D508 Limiter
D509 Limiter
D510 Reverse current
protection
D511 BUSY/TX LED
(Green/Red)
D512~517 Key backlight
D518 Current regulation Key backlight
D520 Discharge
VCO Unit (X58-4540-11) : K2,HK2
(X58-4712-70) : K,HK
Ref. No. Use / Function
Q101 Inverter
Q102 Oscillator
Q103 Oscillator
Q104 TX/RX switch
Q105 TX/RX switch
Q106 Buffer amp
D101 RX VCO
D102 TX VCO
D103,104 RX VCO
D106,107 TX VCO
D109 Modulation
Operation / Condition
BLC
PSB
CM
PTT/TXD
HOOK/RXD
MM/MM1
MIC
ASQ
C575 charge
Busy time green on, TX time red on
KBLC "H" time on
Speed up
Operation / Condition
TX (ST "H") time on
RX
TX
TX (ST "H") time on
Q101 off time on