Xerox Phaser 3300 Servce Manual page 46

Theory of Operation
2-4
Paper Feed Sensing
When paper passes the feed sensor actuator, the photo interrupter signals the
CPU, which releases the image data after certain time.
If the CPU doesn't detect the feed sensor within 1sec. after paper is fed,
paper Jam0 occurs.
The fact whether the print cartridge is inserted or not is detected by CRUM.
After the print cartridge is mounted, the sub-CRUM can read the information
of print cartridge from contact with CRUM involved in print cartridge. If the
information of print cartridge is invalid, it will show invalid sign on a LCD.
Paper Exit Sensing
It detects paper state whether paper gets out from the set with operation of
exit sensor on the HVPS and actuator on the frame. Paper detects the on/off
time of exit sensor by reading D22 of CPU, and the normal operation or jam
information is informed to the CPU. The paper JAM2 is reported.
Cover Open Sensing
The Cover open sensor is located on the HVPS. After the front cover is
opened, +24VS (DC fan, Solenoid, Main Motor, Polygon motor part of LSU
and HVPS), which is supplied to the each unit, is cut off. The cover-open
sensing is operated by the D23 of CPU. In case, the red will be ON for
informing the facts to user.
DC FAN/SOLENOID Driving
The DC Fans are driven by transistor and controlled by D14 (FAN MAIN), E16
(FAN DUPLEX), C23 (PICK-UP CLUTCH), C18 (REGI CLUTCH), D15 (MPF
CLUTCH) of CPU. When it is high, the fan is driven by turning on the TR, and
it is off when the sleep mode is selected.
There are three solenoids, and they are driven by paper pick-up, regi and
MPF signal. It is turned on or off by C23, C18, D15 of CPU. The diode
protects the driving TR from the noise pulse generated when the solenoid is
de-energizing.
Motor Drive
The main motor driving circuits are on the BLDC Motor Assembly Unit. The
Main Controller has the interfacing circuits.
There is a motor driver IC on the motor control board of Motor Assembly Unit.
The exit motor driving circuits are formed when the driver IC is selected.
Phaser 3300MFP Service Manual