Panasonic KX-T2375MXW, Service Manual

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13 CIRCUIT OPERATION
13.1. Bell Detector Circuit
When the bell signal is input between T/R, the signal are outputted at the speaker via the following path: Tel line
→
R1/C1
→
D1
→
Pin 1 of IC1
→
Pin 8 of IC1
→
C6
→
T1
→
C625
→
Speaker
13.2. Line Interface
In talk status, L1 RLY output from pin 25 of IC801 changes to low level, causing Q103, Q101 to turn on and resulting in a line
loop.The loop current flows from D101(+)
→
Q101
→
Q108
→
R124
→
D106 in that order, A pulse signal that repeated
switches between high and low logic is output from pin 26 of the CPU.This switches the line loop on and off, generating the dial
pulse signal.
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KX-T2375MXW