Canon iR1200 Series, Service Manual

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Chapter 3
3-3
PCB.
Image Processing Control Block
The image processing control block has the following functions:
- It subjects the digital image data from the analog processor PCB to enlargement/reduction processing, shading
correction, smoothing, and other image processing, thereby converting it to 600x600-dpi image signals (VD0,
VD0*).
- It converts the analog image data from fax communication into 600x600-dpi image signals (VD0, VD0*).
- It uses a horizontal sync signal (BD0*) as a trigger to send image signals (VD0, VD0*) to the laser unit.
- The image data from the contact sensor is re-arranged, and the intensity of the contact sensor LED is controlled.
Sensor Detection
It detects the state of each sensor of the reader unit and the ADF.
ESS Control
It controls the ESS function used to reduce the power consumption while the machine is in standby state.
Memory Function
The 16MB (as mounted) SDRAM used for the storage of image data is capable of storing about 255 pages in fax
reception made of Canon Fax Standard Chart No.1. The image data is backed up by a vanadium lithium secondary
battery (BAT2), so that it remains intact for about 2 hr after the machine is deprived of power. The 128-KB SRAM
is used to store user data and service data, and is backed up by a lithium battery (BAT1) so that the data may be
retained for about 5 yr after the machine is deprived of power.
Speaker Control (if equipped with fax functions.)
It turns on/off or control the volume of the error sound, key sound, and line monitor sound generated by the speaker.
MEMO:
The volume of the line monitor or the sound of the key sound or the error sound is adjusted in user mode.
Communication Control Block (if equipped with fax functions)
The communication control block detects line signals (CNG, DTMF). The 33.6-kps modem is controlled by the main
CPU on the image processor PCB for modulation and demodulation of transmission/reception data. It also is used to
send the DTMF signal.
3.1.4
DC Controller PCB
0006-2850
Fixing Heater Control Block
The fixing heater control block monitors the temperature reading of the thermistor to ensure that the temperature of
the heater reaches a specific level. If an error is detected in the temperature of the heater, it stops the power to the
heater.
High-Voltage Control Block
The high-voltage control block controls the high voltage for the primary charging roller, developing cylinder,