Bizhub c250i Printing Issues - blotchy, patchy, cloudy, streaky printing

[James Harvey]

I have a problem currently showing long blotchy, patchy, cloudy, streaky type printing.
It appears over all of the print if a page is covered with a colour or image.

It stands out a lot more on the black only printing as the sample shows.
I have not noticed as much on colour prints unless there is a higher percentage of black in the colour.

A brand new black toner was placed in, so it is probably one of the other units or something else?

Standard A4 paper.
Special paper also tried.

Black K toner - replaced (Full).

Drum Unit black - 77%
Developing Unit Black 82%
Fusing Unit 77%
Image Transfer Belt Unit 44%
Transfer Roller Unit 44%

It would be good to know what it might be related to before swapping out hardware.
I do the basic swapouts myself, but I am having to also work in with handing over anything more advanced found to service tech to try.

I can't seem to find a previous example the same to match properly.

[Brad6784]

This is more than likely the black development unit, looks like either poor quality toner or something wrong with the developer. I’ve seen this with original toners on newish or older developer units and I’ve seen this with compatible toners.

I would suggest completing further tests to confirm it is the black development unit - you can try single colour solid test prints, in copy mode select cyan, yellow or magenta, then perform a sky copy or copy something with a lot of background. If you don’t see this effect in these test copies, defo black development unit, good luck!

[doinbox]

If the print feels grainy there's a chance its an HVT issue as I've had that a few times on this range but I'd still try a developer unit first

[James Harvey]

Thanks all, I had suspected a developer unit after two different black toners, but will also keep a potential HVT issue in mind.

[James Harvey]

Just an update for anyone else on this after the fix was made with a service tech visit.
A new developer unit was installed. Something happened with the toner into the developer unit that caused it to go bad.
Waste toner box was also getting a bit full, so that was also changed.
All ok now.

[tsbservice]

Thanks for updating your topic.
You were lucky this time that your compatible toners ruined only black developer unit. Watch out for colors they are EXPENSIVE.