Other Function; Protective Function; Safety; Sleep Function - Canon i-SENSYS LBP5300 Series Service Manual

The low-voltage power supply circuit is to convert AC into DC covering the DC loads.
The block diagram of this circuit is illustrated below.
SW3701
Power switch
Protective circuit
24V generation circuit
The low-voltage power supply circuit is partially activated as soon as plugged in the electrical outlet. When turning ON the power switch (SW3701), whole low-
voltage power supply works.
The AC power is then converted into +24V, +5V and +3.3V covering each of printer DC loads.
The following are the main loads for +24V, +5V and +3.3V power.
+24V: Motors, solenoids, high-voltage power supply PCB, and 500-sheet paper feeder
+5VÅF +5V: Laser driver PCB, high-voltage power supply PCB, color misregistration/image density sensor, control panel, and memory controller PCB
+3.3V: Sensor (photo interrupter), media sensor, environment sensor, video controller, control panel, DC controller, and high-voltage power supply PCB

2.7.1.2 Other Function

2.7.1.2.1 Protective function

/ i-SENSYS LBP5360 / i-SENSYS LBP5300
The low-voltage power supply circuit has protective function against overcurrent and overvoltage to prevent failures in the power supply circuit. Once there flows
an excessive current accidentally to the load side for some trouble such as a short-circuit problem, or overvoltage occurs, it automatically cuts off the output voltage.
In case that no DC voltage is supplied from the low-voltage power supply circuit, turn off the power switch (SW3701) anyway. Do not turn on the power again as
far as the root cause is not found at the load side since the protective function may still work. (see Note) There are two fuses, FU3801 and FU3901, in the circuit
for other protective function. The fuses blow and cut off the AC power, once AC overcurrent flows into the AC line.
To recover the low-voltage power supply in case of functioning the protection, turn the power OFF (by switching off or unplugging) and leave the printer off for
15 seconds or longer, then turn the printer ON again.

2.7.1.2.2 Safety

/ i-SENSYS LBP5360 / i-SENSYS LBP5300
For the safety reason for the users and the service technicians, the +24V DC line is intentionally divided into two ways, +24VA and +24VB.
The +24VA is supplied from the DC controller all the time, whereas the power supply of the +24VB stops when the door switch (SW1) is cut off. The high-voltage
power supply PCB and motors are supplied with the +24VB. They stop when the front cover or upper cover is opened.
This is to protect the users and the service technicians from an electric shock or injury to their hands.
The +24VB also functions as the DOOR OPEN signal. The CPU determines the door open when the +24VB supply stops.

2.7.1.2.3 Sleep function

/ i-SENSYS LBP5360 / i-SENSYS LBP5300
Low-voltage power supply unit
FU3901
Fuse
Fixing contlol
Noise filter
FU3801
Fuse
Noise filter
Low-voltage power supply circuit
Remote switch
control circuit
Zero crossing
circuit
24V ON/OFF
circuit
5V generation circuit
3.3V generation circuit
Printer power suplly
voltage detection circuit
Door open
detection switch
circuit
24VB
24VA
Driver IC
RLD+
RLD-
RSRD
24VB
24VA 3.3V
DC
controller
/PSSWOPEN
IC1001
PSOFF
CPU
ZEROX
PSREM24V
24VA
IC1010
5V
ASIC
3.3V
PS100V
F-2-47
Fixing unit
24VB
Duplexing unit Paper feeder (Option)
3.3V
24VB Feed motor, Drum motor, ETB motor,
Fixing motor, Solenoids
3.3V
Photointerrupters
3.3V
24VB
3.3V
High-voltage power supply PCB
5V
3.3V
Memory controller PCB
5V
24VA
Fan Scanner motor
Color misregistration/Image density
5V
sensor
Laser PCB
Environment sensor
3.3V
Photointerrupters
Video controller PCB
3.3V
5V
Control panel
Chapter 2
0013-8413
0013-8415
0013-8417
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