1. The corona wire is broken

If the corona wire is broken, replace the corona wire.

2. Missing charging roller or poor assembly

If the printing is completely black, it may be due to missing charging roller or improper assembly. This is usually caused by poor installation of the toner cartridge after manual removal. At this time, it is necessary to check whether there is a problem with the charging roller, and reassemble the charging roller.

3. Poor contact of the conductive support of the charging roller or the conductive steel sheet

If the conductive support of the charging roller or the conductive steel sheet is in poor contact, reassemble the conductive support of the charging roller or the conductive steel sheet and check the conductive contact points in the machine.