A3.1.3 E17 Circuit Diagram (Page 3/16) - Oki OKIFAX 5400 Maintenance Manual

E17
A3.1.3 E17 Circuit Diagram
1. Block diagram
The audio monitor circuit on page 3/16 that consists of IC11 (analog switch IC) and IC5
(amplifier) generates the following audio monitor.
•
•
Figure A3.1.3 shows the block diagram of audio monitor circuit.
2. Function
1)
2)
+5 V
from modem
RM
0VA
40838301TH Rev.1
Line monitoring
Buzzer signals
Line monitoring
Send and receive signals are input from the transformer on the NCU board to this
circuit as RM signal and the signal power is input to the IC11. The IC11 adjusts the
monitor volume by MONC0, MONC1 and MONC2 signal under the control of CPU.
Output (high and low) from IC11 passes through the amplifier and fed to the speaker
as a SP signal.
• MONC0/MONC1/MONC2 signal :
Note: In case of transmission mode, the monitor will be available during dialing, but
the monitor will be switched off automatically after the elapse of specified time
(about 5 sec).
Buzzer control
Alarm and other signals (key touch etc.) are input from CPU to this circuit as BZ signal.
The various buzzer signals are sounded under the control of CPU.
CPU
BZ
TR1
MONC0
MONC1
CPU
Figure A3.1.3 Block Diagram of Audio Monitor Circuit
Volume control signal.
IC11
Analog
switch
MONC2
A3 - 4
CN8
Amplifier
1
IC5
2
0VA 0V
Speaker