Brother International HL 1850 Service Manual - Page 215

CHAPTER 6 TROUBLESHOOTING 1-16 Black spots .1. P . • • FkAfr User Check (1) If the problem is not solved after printing a few pages, the drum unit may have glue from label stock on the photosensitive drum surface. Refer to Step 1 in the table below and NOTE in the previous page. (2) The drum unit may be damaged. Install a new drum unit. Possible cause Step Check Drum unit 1 Are the spots at 94mnn intervals? (The problem is not solved after printing a few pages.) Drum connection failure Fixing unit 2 Is the contact between the drum unit and printer body connected correctly? 3 Are the spots at 79mnn intervals? (The problem is not solved after printing a few pages.) High-voltage power supply PCB failure 4 Is the problem solved after replacing the high-voltage power supply PCB? Result Remedy Ground contacts Yes 1) If toner or glue remains stuck, wipe it off gently with a cotton swab. (Refer to NOTE in the previous page.) 2) If the photosensitive drum is scratched or deteriorated (exposed), replace the drum unit. No Clean contact electrode both on the drum unit (8) and in the printer body. Yes 1) Check and clean the heat roller with a cloth dampened with alcohol. 2) Replace the fixing unit. Yes Replace the high-voltage power supply PCB. 6-48