Matsushita Electric KM40108849C3, Service Manual

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12.2. CONNECTOR PIN ASSIGNMENT
Pin no. signal Function Enable
1 VDD Power Supply (5V) —
2 VLCD LCD Power Input —
3 VSS Power Gnd (0V) —
4 DATA Serial Data Input H/L
5 WR Write Data H, L L
6 CS Chip Selection H, L H
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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