Brother HL-1850 Service Manual page 6

TABLE OF CONTENTS
1.3.9 Engine I/O ......................................................................................................................... 3-12
1.3.10 Panel I/O ........................................................................................................................... 3-12
1.4 Engine PCB.................................................................................................................... 3-13
1.5 BR-net PCB.................................................................................................................... 3-13
1.6 Power Supply ................................................................................................................. 3-14
1.6.1 Low-voltage Power Supply ............................................................................................... 3-14
1.6.2 High-voltage Power Supply............................................................................................... 3-15
2. MECHANICS .........................................................................................................3-16
2.1 Overview of Printing Mechanism.................................................................................... 3-16
2.2 Paper Transfer ............................................................................................................... 3-18
2.2.1 Paper supply ..................................................................................................................... 3-18
2.2.2 Paper registration ............................................................................................................. 3-18
2.2.3 Paper eject........................................................................................................................ 3-19
2.2.4 Duplex printing.................................................................................................................. 3-19
2.3 Sensors .......................................................................................................................... 3-20
2.3.1 Cover sensors................................................................................................................... 3-20
2.3.2 Toner sensors ................................................................................................................... 3-20
2.3.3 DX tray sensor / DX paper size sensor............................................................................. 3-21
2.3.4 Rear cover sensor ............................................................................................................ 3-21
2.3.5 Cassette sensor / Paper empty sensor............................................................................. 3-22
2.3.6 Paper eject sensor............................................................................................................ 3-22
2.4 Drum Unit ....................................................................................................................... 3-23
2.4.1 Photosensitive drum ......................................................................................................... 3-23
2.4.2 Primary charger ................................................................................................................ 3-23
2.4.3 Transfer roller ................................................................................................................... 3-23
2.4.4 Cleaner ............................................................................................................................. 3-23
2.5 Toner Cartridge .............................................................................................................. 3-23
2.6 Print Process.................................................................................................................. 3-23
2.6.1 Charging ........................................................................................................................... 3-23
2.6.2 Exposure stage................................................................................................................. 3-24
2.6.3 Developing........................................................................................................................ 3-25
2.6.4 Transfer ............................................................................................................................ 3-25
2.6.5 Fixing stage ...................................................................................................................... 3-26
CHAPTER 4 DISASSEMBLY AND RE-ASSEMBLY.............................. 4-1
1. SAFETY PRECAUTIONS ........................................................................................4-1
2. DISASSEMBLY FLOW ............................................................................................4-2
3. DISASSEMBLY PROCEDURE................................................................................4-3
3.1 AC Cord ........................................................................................................................... 4-3
3.2 Drum Unit ......................................................................................................................... 4-3
3.3 Paper Cassette ................................................................................................................ 4-4
3.4 Network Board (For HL-1870N only).............................................................................. 4-11
3.5 Top Cover ...................................................................................................................... 4-12
3.6 DX Feed ASSY............................................................................................................... 4-16
3.7 Rear Cover..................................................................................................................... 4-20
3.8 Rear Cover R & L / Side Cover R & L ............................................................................ 4-22
3.9 MP Cover ASSY............................................................................................................. 4-23
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