Brother International HL 1850 Service Manual - Page 209

CHAPTER 6 TROUBLESHOOTING 1-7 Black and blurred horizontal stripes HArA4.4.weiii kjVA User Check (1) The drum unit may be damaged. Install a new drum unit. (2) Check the paper used meets the recommended paper specifications. (3) Clean the printer interior and the corona wire in the drum unit. Possible cause Scratch on the drum Toner stuck on the developer roller Step Check , 1 Are the horizontal stripes at 94mm (photosensitive drum) intervals? , 2 Are the horizontal stripes at 39mm (developer roller) intervals? Scratch on the heat roller Corona contact failure High-voltage power supply PCB failure 3 Are the horizontal stripes at 79mm (heat roller) intervals? 4 Are the charge electrodes between the printer body and the drum unit dirty? 5 Is the problem solved after replacing the high-voltage power supply PCB? Result Remedy . Yes The photosensitive drum was scratched. Replace the drum . unit. Yes After printing several pages, the problem will disappear. If not, replace the toner cartridge. Yes Replace the heat roller. Yes Clean both electrodes. Ground contacts (3) Yes Replace the highvoltage power supply PCB. 1-8 Black vertical streaks (in a gray background) Possible cause Translucent stain on the scanner window Corona failure Step Check Result Remedy 1 Is there any dirt on the scanner Yes 1) Clean the scanner window? window. 2) If it is not effective, replace the laser unit. 2 Is the corona wire dirty? Yes Clean the corona wire with the wire cleaner. Ground contacts (2) 6-42