Panasonic KX-T2373MXW, Service Manual

Page: 20 / 35

11.3.2. Telephone Line Interface
11.3.2.1. Circuit operation
· 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
→
D101
→
Q101
→
Q108
→
R124
→
D106
→
D101
→
R
·
The receiving signal flows:
TEL line
→
POS101
→
Q101
→
C113
→
R125
→
C108
→
Q109
→
Q405
→
Q406
→
Speaker
· The transmission signal flows
Mic
→
Q421
→
Q424
→
C435
→
R437
→
Q108
→
POS101
→
Tel Line
20
KX-T2373MXW