Brother International HL 1240 Service Manual - Page 137

CHAPTER 6 TROUBLESHOOTING I-4 All black User Check (1) Clean the corona wire of the drum unit. (2) The drum unit may be damaged. Install a new drum unit. Possible cause Corona failure Step Check 1 Is the corona wire dirty? 2 Is the corona wire broken? Harness connection 3 Are the charge electrodes between the printer body and the drum unit dirty? 4 Is the laser unit connected to the main PCB correctly? High-voltage power supply PCB failure 5 Is the problem solved after replacing the high-voltage power supply PCB? Main PCB failure 6 Is the problem solved after replacing the main PCB? Result Yes Yes Yes Remedy Clean the corona wire with the wire cleaner. Replace the drum unit. Clean both electrodes. Ground contacts ➁ ➂ No Connect the harness between the laser unit and the main PCB correctly. Yes Replace the highvoltage power supply PCB. Yes Replace the main PCB. 6-27