Service manual

MFC-8420/8820D/8820DN, DCP-8020/8025D/8025DN
SERVICE MANUAL
3-1
CHAPTER 3 THEORY OF OPERATION
1. ELECTRONICS
1.1 General Block Diagram
Fig. 3-1 shows a general block diagram.
Control Section
Centronics
parallel interface
USB interface
Host Computer
Control
panel
Printer
data
Fax data
Low- and
high-voltage
power
supplies
AC
Paper
feeding
mechanism
Laser printing unit
*Provided on models supporting facsimile function.
Charging, exposing,
developing,
transferring, and
heat-fixing processes
- Electrical charger
- Laser unit
(including the polygon
motor)
- Laser-sensitive drum
- Developer roller
- Transfer roller
- Heater roller
- Main motor
Scanner unitADF unitNCU*Line Speaker
- CCD unit
- CCD motor
- ADF
motor
Fig. 3-1