I HAVE Konica Minolta Konica Minolta C550 .WHEN I USED COPY OR PRINT EXITING PEAPER IS DIRTY OR HAVE BAR BLACK. PLEASE GUIDE ME

SOURCE: Konica Minolta

When printing black only you are using only a single laying of toner as compared to a 4 layer wen in colour. Usually it is the stock. Hyou tried on a different media type? If it one file only or different ones. If it is a picture, try sending in colour mode, it may improve.
If none of this helps, you may be due for a Service Call.

SOURCE: hello, we have konica minolta bizhub c550, i

TRY

SOURCE: Konica Minolta dirty copies

If your dropping toner your losing bias on your Image Unit. You will probably need a new unit.