35
KX-MB2230JT/ KX-MB2270JT/ KX-MB2515JT/ KX-MB2545JT/ KX-MB2575JT/ DP-MB310JT
6.4. NCU Section ( Fax supported models only )
NCU: (Network Control Unit)
Requires for connecting computers to public communication networks and send a dial signal to call the other party.
6.4.1. General
NCU is the with the telephone line. It is composed of an EXT. TEL. line relay (RLY100), bell detection circuit, TAM interface circuit
and line amplifier. The following is a brief explanation of each circuit.
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 (P23) High Level→Q105 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 (AD17).
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
Refer to Check Sheet for Signal Route of CNG/DTMF detection (P.223).
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.36).
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