Strange Lines - Bizhub C220

[joaopauloooo]

I just bought an used Konica Minolta Bizhub C220 with 284k printed pages in total (220k color and 64k b&w) but I noticed some strange lines that are only noticeable when printing mid-tones. When printing any color at 100% it looks great, no problem.

I have attached a pdf file with the prints of the 4 colors (50%K, 50%C, 50%M, 50%Y),one in each page.
The vertical lines are the drums and I will replace them. (The magenta drum is also very bad with a white spot.)

What I want to know is what is causing those horizontal lines? There are lighter and darker lines in the whole page. They are on every color in the exactly same place and it is more noticeable on cyan and magenta.

Machine info:
All drums: 100%
All Developing units: near 50%
Fusing Unit: 52%
Transfer belt: 95%
Transfer roller: 67%

[allan]

Nice and toasty.

You can clean the coronas by disassembling the thing.
Well the magenta drum has got a scratch and the dev it in question.
What toner is in there?

The dev will go 300K and beyond. Drums almost.

[allan]

Machine looks healthy. Change the DR's first to see if the result is pleasing. Otherwise the DV's too.

[907tec]

My money is on transfer belt and transfer roller. Believe they come together for this model. I really wouldn't worry about it, unless you are printing a lot of half tones where it shows up. If it's too big of an annoyance, you will have to order a new transfer kit for $350-450.

[habik]

IF LEF fed then TX Belt (you can see the same lines on M and C the best) as suggested by 907tec
IF SEF fed then Drums if not cured Devs..

The scratch been pointed out by Allan.

[blackcat4866]

A 15% to 20% halftone would demonstrate your issue better. Otherwise I have nothing to add to the previous comments. =^..^=

[copyman]

FYI you can buy aftermarket belt, blade & fuse to rebuild the transfer belt unit. Less than $100.

I've had great success rebuilding these and the C253 Trans belt units.

[fearless]

if you look at all your test print ,and they all show on the same spot ,it is the transfer belt,you may want to visully check the drum as well.

good luck

[joaopauloooo]

A 15% to 20% halftone would demonstrate your issue better. Otherwise I have nothing to add to the previous comments. =^..^=

Thanks very much for the reply.

I have just made this test (see attached) and you were right, it shows this issue better. The yellow was actually printed, I just couldn't scan it because it was too light. What is your conclusion now?

And after this test I saw another issue, all the color prints are quite lighter on one side and only the K looks the same on the whole page.

[blackcat4866]

I think that I would approach this in two steps. I'd replace the drums first. Then do a gradation and stabilization. Once that is complete I think that you'll see that you need the yellow and magenta developers. When they arrive and you've installed them, do the gradation and stabilization again. =^..^=