External And Controls System; Power Supply; Protective Functions - Canon imageCLASS MF4890dw Service Manual

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Technical Overview > External And Controls System > Power Supply > Protective Functions

External And Controls System

Power Supply

■ Power Supply
Protection
Power
Circuit
Supply
Assembly
24V
5V
Generating
Circuit
Engine Controller PCB
5V 24V 3.3V
LVDS
3.3V
5.5V
DC/DC
Converter
1.0V
Main Controller PCB
2 Technical Overview > External And Controls System > Power Supply > Protective Functions
3.3V
Fixing Assembly
5V
Laser Scanner Unit
24V
Motor Driver PCB
3.3V
5.5V
FAX-NCU PCB
24V
24V
Solenoid
3.3V
LAN
3.3V
Control Panel Unit
5.5V
3.3V
ADF Unit
5.5V
+Reader Unit
F-2-40

■ Protective Functions

● Power protective function
Low voltage power circuit carries the overcurrent preventive function against and overvoltage
preventive function that block the voltage output automatically to prevent the power circuit
brokerage when the overcurrent or overvoltage occur due to load errors such as short circuit
etc.
Thus, when the DC power cannot be output from the low voltage circuit, the protective
function against overcurrent or overvoltage may be working. Since the secondary SW is used
as the power SW, the power supply cord needs to be disconnected when fixing a trouble on
the load side.
Also the circuit carries the 2 fuses (FU201, FU202) as a preventive function (see note 2). The
fuses blow to block the power supply when overcurrent occurs in AC line.
To reset the power supply after protective function activation, leave it unplugged for 2
minutes before plugging it in and turning it on.
● Safety function
The host machine equips the function of stopping 24V of fixing assembly and the high voltage
power unit to avoid users and engineers from getting burned or electric shock.
When the cartridge door is opened, the interlock switch (SW501) is turned off and 24V
supplied to fixing assembly and the high voltage power unit is shut.
Engine controller CPU determines the door open when each interlock switch is turned OFF.
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