Summary of Product
Service Manual
3-15
Samsung Electronics
3.3.1.5 Sensor Input Circuit
3.3.1.5.1 Paper Empty Sensing
The Paper empty sensor (Photo Interruptor) on the engine board informs the state of paper to CPU whether it is empty
or not with operation of the actuator.
When cassette is empty, it detects the fact by reading the D0 Bit of CPU, and then informs the fact by selecting the sec-
ond LED(yellow) among the panel LEDs.
3.3.1.5.2 MP Sensing
By operation of Actuator on the frame, MP Sensor (Photo interruptor) on the engine board informs the state of paper to
CPU whether it is empty or not. It reads the D0 Bit of CPU for recognizing paper in MP, and paper is fed from MP if there
is.
3.3.1.5.3 Paper Feeding/Width Toner Cartridge Sensing
When paper passes the actuator (feed sensor part), it detects the signal of Photo interrupter, informs the paper feeding
state to CPU, and then sprays the image data after certain time.
If it doesn’t detect the feed sensor within 1sec. after paper is fed, paper Jam0 (CPU #_ ) is occurred (Red and Yellow will
be turned on among the OP panel LEDs), and the fact whether the developer is inserted or not is detected with the
same principle. After the developer is mounted, the actuator is operated. The signal from the photo interrupter is detected
when it is passing the actuator of the sensor part. That is the developer ID sensing.
3.3.1.5.4 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 D2 Bit of CPU, and the normal operation or jam
information is informed to the CPU.
The paper JAM2 is informed. (Red, Yellow LED will be turned on among the OP panel LEDs)
3.3.1.5.5 Cover Open Sensing
The Cover open sensor is located on the front cover. After the front cover is opened, +24V (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 D0 bit of CPU, and the developer ID sensing is operated by D7 bit of CPU.
In case, the red LED among OP pnael LEDs will be ON for informing the facts to user.
3.3.1.5.6 DC FAN / SOLENOID Driving
It is driven by transistor and controlled by D6 bit of CPU.
When it is high, the fan is driving by turning on the TR, and it is off when the sleep mode is selected. There are two sole-
noids, and they are driven by paper pick-up and MP signal. It is turned on or off by D4 bit of CPU, and its driving time is
300ms. The diode protects the driving TR from the noise pulse, which is flown when the solenoid id de-energizing.
FAN Driving Circuit is driven by Transistor, and controlled by D6 Bit of
3.3.1.5.7 Motor Driving
The motor driving circuit is formed when the Driver IC is selected in the first place. The A3977 Motor Driver IC is used in
this case. But resistance Rs value of sensing and voltage value of the V reference can be changed by motor driving volt-
age value. The motor driving voltage is calculated with the following formula.
I = Vref / Rs, wherein Vref is (R1x 5V) / (R1+R2).
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