Xerox Phaser 3450 Service Manual page 21

Summary of product
4.2.6. Sensor input circuit
4.2.6.1. Paper Empty Sensing
The Paper empty sensor (Photo Interrupter) on the engine board informs the state of paper to CPU whether it is empty or
not by operation of the actuator.
When cassette is empty, it detects the fact by reading the D24 Bit of CPU, and then displays the fact on the LCD panel.
4.2.6.2. MP Sensing
By operation of the MP Sensor (Photo Interrupter) on frame and Actuator, it informs the state of paper to CPU whether it
is empty or not. It reads the D25 Bit of CPU for recognizing paper in MP, and paper is fed from MP if there is.
4.2.6.3. Paper Feeding
When paper passes the actuator on the feed sensor part, it detects the signal of Photo interrupter, informs the paper feed-
ing state to CPU, and then sprays the image data after certain time.
If it doesn't detect the feed sensor within 1 sec. after paper is fed, paper jam0 (CPU #Y13) is occurred. (Displays on the
LCD panel)
4.2.6.4. Toner Remain Sensing
The Developer terminal is mounted to the joint board located on frame. When the developer is inserted, it is adhered to the
contacting point of the joint board to sense whether the developer exists or not, ID, amount of toner, and so on.
4.2.6.5. Paper Exit Sensing
It detects paper state whether paper gets out from the set with operation of exit sensor on the engine board and actuator
on the frame. Paper detects the on/off time of exit sensor by reading CPU #W11, and the normal operation or jam infor-
mation is informed to the CPU.
The paper JAM2 is informed. (Displays the state on LCD panel)
4.2.6.6. Cover Open Sensing
The Cover open sensor is located on the front cover. After the front cover is opened, +24V and +5V (DC fan, solenoid,
main motor, polygon motor part of LSU, HVPS, LSU Laser diode), which is supplied to each unit, is cut off.
4.2.6.7. DC FAN/Solenoid Driving Circuit
A fan driving circuit is driven by a transistor and a controller which is in the CPU.
It is automatically turned off when a machine turns to sleep mode.
There are two solenoids, and it is driven by an MP signal and a paper pick-up signal.
4.2.6.8. Motor Driving Circuit
A main motor (BLDC) drives a feeding and developing unit and an exit motor (Step) drives a Fuser and an
Exit ass'y.
When printing with a duplex function, it rotates the Exit Motor to a normal/reverse direction. It controls by
dividing the acceleration section, standard speed section, and reducing speed section. A BLDC Motor is
operated by a clock and enable signal, and a Step Motor is managed with an AN8495 driver IC.
Service Manual
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