Brother International HL 1240 Service Manual - Page 5

TABLE OF CONTENTS 4.3 Two Side Printing (Manual Duplexing 2-11 4.3.1 To print on both sides of the paper from the paper cassette 2-11 4.3.2 To print on both sides of the paper from the manual feed slot 2-12 5. CONTROL PANEL OPERATION 2-13 5.1 Ready (Paper) LED Indications 2-13 5.2 Data (Toner) LED Indications 2-14 5.3 Drum LED Indications ...2-14 5.4 Alarm LED Indications ...2-14 5.5 Control Panel Button Operations 2-15 5.6 Other Control Features 2-15 5.6.1 Sleep mode...2-15 5.6.2 Test print mode ...2-16 CHAPTER 3 THEORY OF OPERATION 3-1 1. ELECTRONICS ...3-1 1.1 General Block Diagram...3-1 1.2 Main PCB Block Diagram 3-3 1.3 Main PCB...3-5 1.3.1 ASIC...3-5 1.3.2 ROM...3-8 1.3.3 DRAM...3-9 1.3.4 Optional RAM...3-11 1.3.5 Optional serial I/O ...3-12 1.3.6 EEPROM...3-12 1.3.7 Reset circuit ...3-13 1.3.8 Engine I/O ...3-14 1.4 Engine PCB ...3-14 1.5 Power Supply...3-15 1.5.1 Low-voltage Power Supply 3-15 1.5.2 High-voltage Power Supply 3-16 2. MECHANICS ...3-17 2.1 Overview of Printing Mechanism 3-17 2.2 Paper Transfer ...3-19 2.2.1 Paper supply ...3-19 2.2.2 Paper registration...3-19 2.2.3 Paper eject...3-20 2.3 Sensors...3-20 2.3.1 Cover sensors A and B ...3-20 2.3.2 Toner sensor...3-21 2.4 Drum Unit...3-21 2.4.1 Photosensitive drum ...3-21 2.4.2 Primary charger ...3-21 2.4.3 Transfer roller...3-21 2.4.5 Cleaner ...3-21 2.5 Toner Cartridge...3-21 2.6 Print Process...3-22 2.6.1 Charging ...3-22 iii