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Tx level is
high.........................
Rx level is
high........................
The comparator output is connected to the attenuator control inside IC7.
(5) VOICE DETECTOR
The output of the mic amp (Pin 10 of IC7) is supplied to Pin 13 of IC7 as a control signal for the
voice detector.
(6) ATTENUATOR CONTROL
The attenuator control detects the setting of the volume control through Pin 24 of IC8 and
automatically adjusts the volume for changing ambient conditions.
(7) TRANSMISSION SIGNAL PATH
The input signal from the microphone is sent through the circuit via the following path:
(8) RECEPTION SIGNAL PATH
Signals received from the telephone line are output to the speaker via the following path:
(9) OFF-HOOK MONITOR CIRCUIT
The input signal from the handset microphone is output through the speakerphone circuit.
(10) CIRCUIT DIAGRAM FOR SIGNAL PATH
Refer to page Schematic diagram.
9. TROUBLE SHOOTING GUIDE
9.1. NO OPERATION
Pin 23=Pin 20-6mV
Pin 23=Pin 20-150mV
22
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