Brother International HL 1850 Service Manual - Page 205

CHAPTER 6 TROUBLESHOOTING 1-3 Completely blank Possible cause Developing bias contact failure Drum unit Step Check 1 Are the developing bias contacts between the printer body and drum unit dirty? 2 Are the drum shaft and drum electrode of the printer body connected correctly? Drum unit failure 3 Is the problem solved after replacing the drum unit? Toner cartridge failure 4 Is the problem solved after replacing the toner cartridge? Scanner ' 5 . Is the scanner harness harness connected securely? connection (Check if there is any play in failure , . the connection.) Main PCB failure 6 Are printing signals being input to the laser unit? Laser unit failure Is the problem solved after . replacing the main PCB? 7 Is the scanner interlock lever damaged? Is the scanner mirror broken or loose? Result Remedy Yes Clean the electrodes at both sides. Yes Clean the shaft and the electrode. No Check the connection between the shaft and the electrode. Yes Replace the drum unit. Yes Replace the toner cartridge with a new one. No Reconnect the connector correctly. Yes Replace the main PCB. , Yes Replace the laser unit. No Replace the highvoltage power supply PCB. Ground contacts (4) (1) (1) 6-38