Brother International HL 1850 Service Manual - Page 204

HL-1850/1870N SERVICE MANUAL 1-2 LP Dark n User Check (1) Check the paper used meets the recommended paper specifications. (2) Check the printer's environment. High temperature and high humidity conditions can increase the amount of background shading. (3) Clean the corona wire with the wire cleaner. (4) Try installing a new toner cartridge or drum unit. Possible cause Corona failure (contact failure) Drum unit failure Toner cartridge failure High-voltage power supply PCB failure Main PCB failure Engine PCB failure Step 1 2 3 4 5 6 Check Are the charge electrodes between the printer body and the drum unit dirty? Is the problem solved after replacing the drum unit? Is the problem solved after replacing the toner cartridge? Is the connections of the connector between the highvoltage power supply PCB and the engine PCB secured correctly? Are there any disconnected connectors? Are there any disconnected connectors? Result Yes Yes Yes Yes No No Remedy Clean both electrodes. Replace the drum unit with a new one. Replace the toner cartridge with a new one. Replace the highvoltage power supply PCB. Replace the main PCB. Replace the engine PCB. Ground contacts 6-37