Ncu Pcb (If Equipped With Fax Functions); Modular Jack Pcb (If Equipped With Fax Functions); Sensor Relay Pcb - Canon iR1200 Series Service Manual

Chapter 3
Communication Control
Communications with the PC are controlled using a bi-directional parallel interface (IEEE std 1284-1994) or USB
(Ver. 1.1). The communication protocols used for bi-directional communications include: Nibble, ECP, Rapid Port.
The communication with the image processor PCB by means of a video interface are also controlled.
USB Serial Number Notice Function
The USB serial number is communicated to the PC.
Smoothing
The 300 x 300-dpi image data from the PC is converted into image data equivalent of 1200 x 600 dpi; or, 600 x 600-
dpi image data is converted into data equivalent of 2400 x 600-dpi.

3.1.12 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 inside 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.

3.1.13 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.

3.1.14 Sensor Relay PCB

Relay the connection between the DC controller PCB and the sensors below
- Humidity sensors (HS)
- Toner bottle sensor (PS11)
3-6
0006-2864
0006-2865
0006-2866