KX-TS2363CAW, KX-TS2363UAW - Panasonic Telephone Service Manual (repair manual). Page 9

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• On hook

Q101 is open, Q101 is connected as to cut DC loop current and cut the voice signal.

• Off hook

Q101 turns on thus providing an off-hook condition (active DC current flow through the circuit) and the following signal flow id for
the DC loop current
T 

→ POS101 → D7 → Q101 → Q108 → R124 → D106 → D10 → R

• Receiving signal flow :

TEL line 

→ POS101 → Q101 → C113 → R125 → C108 → Q109 → Q405 → Q406 → Headset Jack → Handset SP

• Transmission signal flow :

Mic 

→ Q424 → C435 → R437 → Q108 → Pos101 → Tel Line

This circuit is used to sense the status of the line (busy tone or dial tone) during Auto Redial.

D7 

→ Q101 → C201 → R201 → R205 → Pin 5 of IC201 → Pin 1 of IC201 → D202 → R208 → Q201

When the subscriber hangs-up, check the intermittent tone. If cycle tone is detected, the collector of Q201 goes to a low logic.

This circuit is used for to initialize the microcomputer when it incorporates batteries.

When the batteries is inserted into the unit, then the voltage is regulated by IC304 and power is supplied to the CPU. The set
can operate beyond point A in the circuit voltage diagram.

VCC

Battery

GND

Reset

Power

Down

A

Vcc

Reset

CPU Reset

Power down