Panasonic DX-600 Service Manual page 218

6.2.5 Line Monitor Circuit
The Line Monitor Circuit consists of an operational DAA (The secondary side chip) and its peripheral
circuits. Its function is to monitor the dial tone, DTMF tone, response signals, etc. over the speaker. It also
sounds the output of the key touch tones, alarm tones, etc. from the panel CPU over the speaker. The
Received Signals are output from DAA of Secondary circuit, and through Analog AGC, Electronic Volume,
Amplifier and over the speaker.
The monitor tone from the phone line and the buzzer tone from the panel can be adjusted from the Control
Panel.
Line Monitor Signal
(from AGC Circuit)
Buzzer Clock
(from Control Panel Unit)
Buzzer Tone Switch
(from Output Port)
Edition 1.0
Volume
Control
Circuit
(IC21)
Level Control
Circuit
(Q3)
Line Monitor Circuit
Block Diagram
218
-
(IC20, 2)
+
AGD
(+2.5VDC)
DX-600/800
Speaker
Amplifier
(Q4,5)
Speaker
APR 2002