Ncu Section; General; Ext. Tel. Line Relay (Rly100); Bell Detection Circuit - Panasonic UF-5500 Service Manual

UF-5500 / 4500
6.4.

NCU Section

6.4.1.

General

This section is the interface between the telephone line and external telephone. It is composed of an EXT. TEL line relay (RLY100),
bell detection circuit, TAM interface circuit and line amplifier.
6.4.2.

EXT. TEL. Line Relay (RLY100)

1. Circuit Operation
Normally, this relay switches to the external telephone side and switches to the open side while OFF-HOOK.
IC300 (R33) High Level→Q100 ON→RLY100 (ON)
6.4.3.

Bell Detection Circuit

1. Circuit Operation
The signal waveform is indicated below. The bell signal input to IC101 and ring detected signal output from pin 15 of IC100.
IC300 monitor this signal and judged as bell.
TEL LINE→IC101 (8,9 - 5,6)→IC100 (9,10 - 15)→IC300(AA25)
Between the Tip and Ring
from the telephone line
IC100 (15) IC300 (AA25)
6.4.4.

Remote FAX Activation Circuit

1. Function
Another telephone connected to same line activates the unit to the FAX mode by using a DTMF signal.
2. Signal Path
TEL LINE→IC101 (8,9 - 5,6)→IC100 (9,10 - 5)→IC300(AD26)
6.4.5.

TAM Interface Circuit

This circuit is to switch between FAX receiving and the external TAM's message recording automatically.
For details, please refer to TAM Interface Section (P.37).
48V
36
about 150V