Vco Unit - Kenwood TK-780 Service Manual

Ref. No. Use / Function
Q24 W/N switch
Q25 TOF switch
Q26 Inverter
Q27 SB switch
Q28 SB SW control
Q29 H/L switch
Q30 SB SW control
Q31 SB SW control
Q32 DET mute
Q202 LNA
Q203 RF amp
Q204 RF amp
Q300 Buffer amp
Q301,302 Active filter
Q401 Short protection
Q402 W/N switch
Q403 W/N switch
D1~6 Protection
D7 HOR protection
D8,9 Protection
D11 OR gate
D12~14 Protection
D15 HT switch
D16 Reverse protection
D17 Protection
D20 Reverse protection
D21 Protection
D22,23 W/N CF change
D24 Over current
protection
D26 Reverse protection
D27 Power detection
D28 Protection
D30 Power detection
D31 Reverse protection
D32 Surge absorption
D34 Protection
D35 Charge
D37 Reverse protection
D206~208 BPF tune
D209,210 Usable temperature
range
D211 ANT swtich
D212,213 ANT switch
TX-RX Unit (B/2) : Control Section
Ref. No. Use / Function
IC501 LPF, amplification
IC502 Amplification
IC503 Base voltage/
Buffer amp
IC504 Audio processor
DESCRIPTION OF COMPONENTS
Operation / Condition
Wide time on
Q22 on time on
Power switch "L" time on
Q28 on time on
Q30 on and Q31 off time on
High power time "H"
Power on time on
DC 20V and over time on
TX time on
TX drive first
TX drive last
PLL
IC400 out short time on
Wide time off
Wide time on
AF mute
IGN
5V (IGN)
B
DC 20V and over time on
DEO
TX time on
Operation / Condition
LSD
AF, HSD
ASQ
Compander, MIC amplifier, ALC,
Modem, AF filter, IDC
Ref. No. Use / Function
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 BSFT "H" time clock shift on
Q511 FSW swtich
Q512 Key backlight switch KBLC "H" time on
Q513 Key backlight switch KBLC "H" time key backlight on
Q515 Key backlight switch
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

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
D104 RX VCO
D107 TX VCO
D109 Modulation
TK-780
Operation / Condition
MO, DEO, EMG, MI switch
DTMF detection
LR, LG, KBLC, MM1, T/R, KEY,
BSFT, PA2 output
Power on time "L" output
5C (Control unit)
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
FSW "L" time foot switch on
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
Reset pulse
Operation / Condition
TX (ST "H") time on
RX
TX
TX (ST "H") time on
Q101 off time on
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