D. Low-voltage Power Supply Circuit
1. Outline
The AC voltage input from the inlet is converted to the DC voltage in the rectification circuit,
transformer, and power supply circuits, and then supplied to the printer as +24VDC, +5VDC,
and +3.3VDC.
When the cartridge door is opened, the door switch (SW301) is turned OFF and the +24VU
supplied to the high-voltage circuit is cut OFF. At the same time, the DOSNS signal becomes
“L”, and the CPU detects that the cartridge door is open and stops the printer.
The AC voltage is supplied to the fixing heater via the fuse (FU101), noise filter, relay, and
triac.
+3.3VDC is supplied to the ICs on the engine controller PCB, BD PCB, and interface controller
PCB.
+5VDC is supplied to the ICs on the engine controller PCB, laser/scanner driver PCB, inter-
face controller PCB, and sensors.
+24VDC is supplied to the high-voltage power supply circuit, main motor, scanner motor, and
solenoids.
Figure 2-2-6
CHAPTER 2
2 - 12
+24VU
+5V
+5V
+5V
+24V
+24V
+5V
+24V
+5V
+24V
+24V
+3.3V
+3.3V
Inlet
Fixing heater
Main motor
Solenoid
High-voltage
power supply
circuit
Noise
filter
Interface
controller
PCB
Laser/scanner
unit
+24V
power
supply
circuit
+5V
power
supply
circuit
Engine Controller PCB
Sensors
DOSNS
+3.3V
power
supply
circuit
Sensor
(T501)
Main
motor
drive
circuit
Noise
filter
Rectifi-
cation
circuit
Transformer
Overvoltage
detection
circuit
Overcurrent
detection
circuit
Door switch
(SW301)
CPU
Relay
Triac
Surge absorber
(IC501)
Control IC
Fuse
(FU101)
Fuse
(FU102:100/127V only)