New Bizhub C8000 Printing quality big problem

[djchampion]

Hello everybody

Konica installed a second c8000 in our company one month ago.

Till now they have not managed to correctly install or set up the machine. Long story

The issue (https://www.dropbox.com/s/xm8ep8793x02ahq/IMAG0189.jpg) is that every black or almost black print look like this i a picture.

They suggested paper change, but we tried 3 different vendors.

I managed to learn that the problem is common and konicaminolta knows about it but they have no idea what is the cause.

I tried several hours set up the settings (heater temperature, other paper, external temperature)

We think that the white stripes is a the unfixed toner (gogle translate ) ant cause of this is wrong temperature or transfer unit in one side is off course.

Please if anyone has a similar problem or information whats going on in that machine - HELP

[pepper38_cnd]

It would help if we knew what the picture was supposed to look like, maybe a test print from the Fiery would have been a better sample to provide. I have seen were the Fiery printing printed all grey no blacks but prints from the copier engine were fine, this turned out to be a bad video interface card in the Fiery controller as well as a bad cable. My thought was a damaged cable caused the video card problem , anyway replacing both resolved the issue. Note this was on a C6000 but similar.

Where did you get the idea that this is a very common problem?

[djchampion]

Maybe these pictures can help you. Only black made of black toner and mixed all together. No picture no graphic.

https://www.dropbox.com/s/40weerx2mxrnnjz/IMAG0217.jpg

https://www.dropbox.com/s/vf473iydk1kqhea/IMAG0218.jpg

https://www.dropbox.com/s/dfiqdp94529wbvt/IMAG0219.jpg

After three weeks of searching the cause, one of the technicians admitted that the problem exists not only in our machine, and they do not know too much how to fix

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[Mick01]

What thickness of stock are you using (in Microns not GSM). This looks like poor transfer on the trailing edge. you can get this issue with thick stock that is not cut the correct grain direction.
Try thick stock that is under 350 micron and is cut in the short grain direction.
Failing that there is a modification that can be placed inside the transfer belt unit that helps this issue.

[djchampion]

Can you say more about this modification ??

I tried the solution of paper.

slight improvement

[Mick01]

There is a guide that gets fitted to the inside of the transfer bely unit. This holds the transfer belt out sligtly at the bottom to help with this issue.
Does this issue only happen with thick paper?

[Captain Jack]

Has the tech tried to adjust the AC and DC transfer adjust timing lead and trail edge, looks like the transfer voltage is switching off before paper edge reaches transfer belt.

[SCHWARZ]

Try change the Lower Belt Unit on the Fusing Unit with the new one.

[djchampion]

There is a guide that gets fitted to the inside of the transfer bely unit. This holds the transfer belt out sligtly at the bottom to help with this issue.
Does this issue only happen with thick paper?

Yes. 135-170g fail no matter if its coated or not. 3 vendors no difference

the 350g paper coated or not is ok, no matter what vendor.