C280 black quality

[gablog]

Hi,
I have KM C280 with black quality problems. A few days ago, the printer started to make vertical strips on whole page. I have replaced K drum unit and ITB and nothing changed. The printer has around 230k

Errors on screen: P-9, P-21. See the attached picture (printed whole black page). Other colours prints fine.

I'd be glad if you have a solution for this.

Thanks!

[scanmc]

I would check out the K DV unit

[tsbservice]

Replace black developer unit.o

[copyman]

+3 on developer unit

[mascan42]

Definitely the dev unit. That's the only thing that makes those diagonal patterns.

[aberock]

looks like dv k depleted .