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CIRCUIT DESCRIPTION
11.2.4.5 Sensing Circuit
1) Cover Open Sensing
Cover Open Sensor is located on the top right side of the Cover Open Board. When the front cover opens, it shuts off
+24V(DC fan, Solenoid, Main Motor, LSU Polygon Motor and HVPS) supplied to each unit. B2 Bit of U4 senses cover open
by sensing the developing section with B111 Bit of U18. In this case, the red LED, which is located on top of the OP Panel
informs the user of the situation.
2) Paper Exit Sensing
The exit sensor assembled on the engine board and the actuator attached to the frame detect the paper exiting the printer.
The paper recognizes the On/Off time of the exit sensor through B5 Bit of U4 and notifies the normal operation or jam
information to the CPU. Paper JAM2 is also notified.(Both Red & Yellow LED from OP Panel Let go on)
11.2.4.6 LSU Circuit
1) Polygon Motor (+24V)
Polygon motor inside the LSU rotates by 'PMOTOR*' signal. It passes Transient section and reaches the motor section,
'LREADY*' signal is notified to U18 #115 pin. When LSU uses external clock for the motor rotation frequency, 'CLOCK' pin
accepts the necessary frequency. Clock circuit is composed inside the engine. Crystal frequency of 58.36 MHz is activated
by Engine CPU and uses 3562Hz for the rotation frequency of the polygon motor.
2) Laser (+5V)
When the laser is turned on by 'LDON*' signal, horizontal scan takes place due to the 6 sided reflection mirror(Polygon
mirror) attached to the polygon motor, which rotates in clockwise direction. At this time, when the laser beam reaches the
starting corner of each surface, 'HSYNC*' signal(pulse) is activated. The video controller uses 'HSYNC*' signal to form left
margin of the image.(horizontal synchronous signal) When the 'Vdout*' signal in inputted to the LSU, it becomes 'LDON*'
and ANDring to investigate suitable laser beam(Vdout data contained).(ON/OFF switching)
11.2.4.7 Clock Circuit
Clock uses 4 X-Tal. CPU is operated by 50MHz. USB is operated by 30MHz X-tal. Video Clock is operated by 23.88MHz.
11.2.4.8 Memory Circuit
CPU initialization is composed of Flash-Rom capable of PGM, DRAM capable of reading and writing data and the Font
Rom, which supports font in PCL6 operation. Due to the variation of Flash and Font Rom by models, basic control of 16Bit
for Rom and 32Bit for Ram is necessary. Domain of Flash Rom is divided into Boot and PGM. PGM can be changed by
download. The storage RAM for the data download from PC is composed of 2MByte * 2.
11.2.4.9 DCU Interface Circuit
DCU(Diagnostic Control Unit) tests the LBP and used as a tool in Trouble-shooting and according to it's purpose,
Diagnostic code, Normal Status code and Error Status code can be applied. At this time, Diagnostic Test takes place
through 'DCU-DIN' signal and the Normal/Error status check takes place through 'DCU_DOUT' signal. 'DCU_CLK' is the
DCU clock input unit.(CLK Frequency : approximately 17.6KHz)
11.2.4.10 HVPS Interface Circuit
HVPS Interface section is composed of various control areas. When high voltage on signal is received from the engine
CPU, each high voltage turns on according to the electric photo process. The signals that turn on the high voltage are
'THV_EN', 'DEV_PWM', 'MHV_PWM', 'THV_PW,M' and the 'THV_READ, which feedback the results of transfer
environment to the CPU.
Summary of Contents for Phaser 3450
Page 12: ...3 4 Specifications Service Manual ...
Page 28: ...4 16 Summary of Product Service Manual ...
Page 75: ...6 20 Alignment Adjustments Service Manual ...
Page 103: ...7 28 TROUBLESHOOTING Service Manual ...
Page 129: ...9 2 BLOCKDIAGRAM Service Manual ...