Canon SmartBase 1270D, Руководство по обслуживанию

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COPYRIGHT © 2002 CANON INC. 2000 2000 2000 2000 CANON SmartBase PC1210D/1230D/1270D REV. 1 MAR. 2002
CHAPTER 4 OPERATION
4-10
1.3.2.10 NCU PCB (if equipped with fax functions)
2-Line/4-Line Conversion Circuit
Signals from a 2-line telephone line are converted into 4-line signals (transmission signals
and reception signals). Also, the transmission signals from the image processor PCB are
prevented from entering the reception circuit.
Dial Pulse Generation Circuit
The dial pulse generation circuit generates dial pulses by turning on and off the relay in-
side it according to the control signals from the image processor PCB. It then sends the dial
signals to the telephone line by way of the modular jack PCB.
Off-Hook Detection Circuit
An off-hook state is detected with reference to the direct current flowing into the circuit,
occurring when the telephone connected to the telephone terminal of the modular jack PCB
is off the hook.
Line Voltage Conversion Circuit
The primary side of the NCU PCB is controlled using a line voltage of +48 VDC. In light
of this, the DC component is cut by the capacitor, and only the audio signals are converted
into voltages suited to the modem level.
1.3.2.11 Modular Jack PCB (if equipped with fax functions)
The signals from the 2 modular jacks (for telephone line and telephone connection) are
communicated to the line voltage conversion circuit of the NCU PCB, and the signals from
the fax are communicated to the telephone line.