It is only printing a one colour background,i can not print or photocopy a full coloured document,why.

SOURCE: Printing colours?

solutions :
Try changing consumables, if near emty or maybe with defect.
If it does't help, there may be problem with cleaning system, then you have to call for service.

First try consumables

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 ?

SOURCE: Dark Blurry Ink Line

When I print darker color images I get what I call Zebra stripes across the picture on a slant about 1/2 inch apart. Changed the toner and the drums are at 45% capacity. Any suggestions. Thank you.

SOURCE: Print colours on a Konica Bizhub C253 are faint on a Mac.

REPLACED DRIVERS
http://download6.konicaminolta.eu/konmin/servlet/KonMinMaster;jsessionid=17E986D9EF284DC5D5FF8F891C5230C0.node03?path=../search.jsp&mode=show&document=56501

SOURCE: Colour printing

Hi Alan,
Please ensure that the printer driver is set correctly.
Go to your Printer & Faxes menu, right click the C250, click printing preferences, click the Quality tab and make sure Colour is selected. Apply the changes and bingo!
The above assumes you are using Windows and a PCL driver.
Hope it helps

Regards

Taminol