This service manual contains basic information required for after-sales service of the laser
printer (hereinafter referred to as "this machine" or "the printer"). This information is vital to the
service technician to maintain the high printing quality and performance of the printer.
This service manual covers the HL-1850/1870N printers.
This manual consists of the following chapters:
CHAPTER 1: GENERAL
Features, specifications, etc.
CHAPTER 2: INSTALLATION AND BASIC OPERATION
Installation conditions, Installation procedures, basic operation of the printer
CHAPTER 3: THEORY OF OPERATION
Basic operation of the mechanical system, the electrical system and the
electrical circuits and their timing information.
CHAPTER 4: DISASSEMBLY AND RE-ASSEMBLY
Procedures for disassembling and re-assembling the mechanical system.
CHAPTER 5: PERIODIC MAINTENANCE
Periodical replacements parts, consumable parts, etc.
CHAPTER 6: TROUBLESHOOTING
Reference values and adjustments, troubleshooting image defects,
troubleshooting malfunctions, etc.
CHAPTER 7: HIDDEN FUNCTIONS
Professional menu mode and Service menu mode, etc.
APPENDICES: Serial No. descriptions, Drum life & page counter, Diameter / circumference
of rollers, Connection diagrams, PCB circuit diagrams, etc.