HL-1850/1870N SERVICE MANUAL
3-1
CHAPTER 3 THEORY OF OPERATION
1. ELECTRONICS
1.1
General Block Diagram
Fig. 3-1 shows a general block diagram of the HL-1850 and the HL-1870N printers.
Optional RAM (DIMM)
(max. 128Mbytes)
Ethernet
10/100 Base TX
Expansion
memory I/O
PCI bus
Video control block
Engine control block
Operation block
(Control panel)
Control system
Low-voltage power
supply block
High-voltage power
supply block
Laser unit
Drive block
(DC motor)
Drum unit
Transfer block
Drum
Charging
block
External device
External device
Paper tray unit
Paper cassette
MP tray
Fixing unit
Paper eject block
Paper feed system
Image generation system
Interface block
(Parallel / USB)
RAM 8MB
Paper dust
cleaner block
Developing
block
Toner cartridge
Network board
Duplex
printing unit
(Standard for HL-1670N
Option for HL-1650)
Fig. 3-1
HL-1850
HL-1870N
Summary of Contents for HL-1870N
Page 15: ...HL 1850 1870N SERVICE MANUAL xiii ...
Page 77: ...CHAPTER 2 INSTALLATION AND BASIC OPERATION 2 48 ...
Page 82: ...HL 1850 1870N SERVICE MANUAL 3 5 Fig 3 5 ...
Page 91: ...CHAPTER 3 THEORY OF OPERATION 3 14 Fig 3 15 ...
Page 101: ...CHAPTER 3 THEORY OF OPERATION 3 24 ...
Page 109: ...CHAPTER 4 DISASSEMBLY AND RE ASSEMBLY 4 2 ...
Page 131: ...CHAPTER 4 DISASSEMBLY AND RE ASSEMBLY 4 24 Fig 4 39 ...
Page 141: ...CHAPTER 4 DISASSEMBLY AND RE ASSEMBLY 4 34 Never touch the surface of the heat roller ...
Page 148: ...CHAPTER 4 DISASSEMBLY AND RE ASSEMBLY 4 41 ...
Page 158: ...CHAPTER 4 DISASSEMBLY AND RE ASSEMBLY 4 51 Fig 4 80 ...
Page 160: ...CHAPTER 4 DISASSEMBLY AND RE ASSEMBLY 4 53 Fig 4 82 ...
Page 167: ...CHAPTER 4 DISASSEMBLY AND RE ASSEMBLY 4 60 Fig 4 91 ...
Page 169: ...CHAPTER 4 DISASSEMBLY AND RE ASSEMBLY 4 62 Fig 4 93 ...
Page 172: ...CHAPTER 4 DISASSEMBLY AND RE ASSEMBLY 4 65 Fig 4 97 ...
Page 174: ...CHAPTER 4 DISASSEMBLY AND RE ASSEMBLY 4 67 3 27 Harness Winding Form ...
Page 183: ...CHAPTER 5 PERIODIC MAINTENANCE 5 8 ...
Page 186: ...HL 1850 1870N SERVICE MANUAL 5 11 ...
Page 194: ...CHAPTER 6 TROUBLESHOOTING 6 8 error in this chapter ...
Page 202: ...CHAPTER 6 TROUBLESHOOTING 6 16 ...
Page 205: ...HL 1850 1870N SERVICE MANUAL 6 19 ...
Page 210: ...CHAPTER 6 TROUBLESHOOTING 6 24 ...
Page 237: ...HL 1850 1870N SERVICE MANUAL 6 51 No Refer and compare with I 15 ...
Page 255: ...HL 1850 1870N SERVICE MANUAL 6 69 ...
Page 261: ...CHAPTER 7 HIDDEN FUNCTIONS 7 6 DRAM CHECK START START DRAM TEST Tests DRAM data ...
Page 270: ...HL 1850 1870N SERVICE MANUAL 7 15 ...
Page 271: ......
Page 272: ...Appendix 1 Connection Diagram HL 1850 1870N A 1 ...
Page 273: ...Appendix 2 Main PCB Circuit Diagram HL 1850 1870N 1 6 CODE LJ8453001 B512078CIR 1 6 A 2 NAME ...
Page 274: ...Appendix 3 Main PCB Circuit Diagram HL 1850 1870N 2 6 CODE LJ8453001 B512078CIR 2 6 A 3 NAME ...
Page 275: ...Appendix 4 Main PCB Circuit Diagram HL 1850 1870N 3 6 CODE LJ8453001 B512078CIR 3 6 A 4 NAME ...
Page 276: ...Appendix 5 Main PCB Circuit Diagram HL 1850 1870N 4 6 CODE LJ8453001 B512078CIR 4 6 A 5 NAME ...
Page 277: ...Appendix 6 Main PCB Circuit Diagram HL 1850 1870N 5 6 CODE LJ8453001 B512078CIR 5 6 A 6 NAME ...
Page 278: ...Appendix 7 Main PCB Circuit Diagram HL 1850 1870N 6 6 CODE LJ8453001 B512078CIR 6 6 A 7 NAME ...
Page 284: ...Appendix 13 High voltage Power Supply PCB Circuit Diagram A 13 NAME High voltage PS Circuit ...
Page 303: ...APPENDIX A 32 ...