I have replaced black drum unit in bizhub 550, but my print is light?

SOURCE: paper feed and colour problems with Konica Minolta bizhub c250

any stripes are usually caused by imagining unit, first use the tool in front cover to clean laser glasses. inspect IU drums for stripes maybe youll need to change them. is the page coming out ok, but picture is printed crookedly ?

Konica Minolta Error Codes and Solutions

• 210 Answers
• Posted on Aug 23, 2009

SOURCE: How do I reset the Unit Life after replacing black imaging unit?

Just reset the chip. More details you can find here: http://www.chipreset.eu

SOURCE: Bizhub C350 Black smudges on prints

Sounds like you may have a bad fusing roller. Run some blank sheets. If the smudges start to fade, that's your trouble. When the fusing roller is bad it doesn't clean as well, so when you run bold text or anything that has higher than normal toner coverage, there will be more build up on the fusing roller that then transfers to the paper.

SOURCE: bizhub c 250

Run stabilizer and gradation. Also check color registration.

SOURCE: I have a konica minolta

check your toners? are they refills? generally speaking its either the toners or photo conductor unit (drum) worst case scenario could be the laser assembly.