Xerox Phaser 3435 Service Manual page 209

Flash Memory
It stores the system program and downloads system program through the PC Interface.
• Capacity: 16M Byte (NOR Flash)
• Access Time: 90ns
• Page read Time: 25ns
SDRAM
It is used as swath buffer, system working memory area, etc. while Printing.
• Capacity: The 64M Bytes is for this model (64M: Printing System Working Memory Area)
Sensor Input Circuit
• Paper Empty Sensing
The Paper empty sensor (Photo Interrupter) on the HVPS 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 E20 of CPU, and then informs
the fact by displaying the RED.
• MP Sensing
By operation of Actuator on the frame, an individual MP Sensor (Photo interrupter)
informs the state of paper to CPU whether it is empty or not. It reads the D17 of CPU for
recognizing paper in MP, and paper is fed from MP if there is.
• Paper Feeding/With Print Cartridge Sensing
When paper passes the actuator (feed sensor part), it detects the signal of Photo inter-
rupter, informs the paper feeding state to CPU, and then sprays the image data after cer-
tain time. If it doesn't detect the feed sensor within 1sec. after paper is fed, paper Jam0 is
occurred (LED will be display RED color). The fact whether the developer is inserted or
not is detected by CRUM. After the developer 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 or LED.
• 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 read-
ing D22 of CPU, and the normal operation or jam information is informed to the CPU.
The paper JAM2 is informed. (LED will be display RED color)
• 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
It is driven by transistor and controlled by D14(FAN MAIN), E16(FAN DUPLEX),
C23(PICK-UP CLUTCH), C18(REGICLUTCH), D15(MPF CLUTCH) 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 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, which is flown when the solenoid id de-energizing. FAN Driving Circuit is
driven by Transistor, and controlled by D14, E16 of CPU.
Phaser 3435
General Procedures and Information
5/08 6-23