Brother International HL-1070 Service Manual - Page 71

I-3 Completely blank Possible cause Developing bias contact failure Drum unit Drum unit failure Scanner harness connection failure Main/Driver PCB connection failure Scanner unit failure 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? 3 Is the problem solved after the drum unit is replaced? 4 Is the scanner harness connected securely? Is there any play in the connection? 5 Are printing signals being input to the scanner? Is the problem solved after the main PCB or the driver PCB replaced? 6 Scanner interlock lever damaged. Scanner mirror is 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 Reconnect the connector properly. Yes Replace the main PCB or the driver PCB. Yes Replace the scanner unit. No Replace the H.V. power supply. HV.GND contacts (Fig.4-5) ➆ ➀ ➀ IV-7