Kenwood KRK-14H Service Manual page 7

2.2.2.3 Audio circuit
2.2.2.3.1 Audio circuit overview
KRK-15B has one RX Audio input channel (AFI+/-), two RX Audio output channels (AFOA+/- and AFOB+/-), one TX Audio output
channel (MIC/ ME), and two TX input channels (MICA+/- and MICB+/-). Selection of Audio input / output channels (AFOA/ AFOB/
MICA/ MICB) and other audio path are controlled by Mobile transceiver's MPU through I/O expander IC (IC7).
2.2.2.3.2 RX Audio path
Speaker voice sounds of KCH-19 which received by Mobile transceiver are passed through KRK-15B and KRK-14H.
Receive audio for KRK-14H given from AFI+/- has outputted to AFOA+/- or AFOB+/- terminal through IC5, IC8, IC9 and IC10 as fol-
lows.
2.2.2.3.3 TX Audio path
Microphone signals Mobile transceiver which given by KCH-19 are passed through KRK-14H and KRK-15B.
Transmit audio given from MICA+/- or MICB+/- have outputted to MIC / ME terminal through IC4 and IC1 as follows.
2.2.2.4 Control circuit
The control circuit consists of followings;
(1) Convert serial communication signal (IC2)
(2) Convert audio path control signal from Mobile transceiver (IC7).
CN1
AFI
Vref
MIC
IC1
Fig.2 Simplified audio circuit
CN1
AFI
Vref
MIC
IC1
CN1
AFI
Vref
MIC
IC1
IC5
IC9 / IC10
CN3 / CN4
IC8
IC4
IC5
IC9 / IC10
CN3 / CN4
IC8
IC4
Fig.3 RX audio path
IC5
IC9 / IC10
CN3 / CN4
IC8
IC4
Fig.4 TX audio path
AFOA / AFOB
MICA / MICB
AFOA / AFOB
MICA / MICB
AFOA / AFOB
MICA / MICB
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