New Bizhub C8000 Printing quality big problem

[Guest]

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]

Re: New Bizhub C8000 Printing quality big problem

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]

Re: New Bizhub C8000 Printing quality big problem

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

[JustManuals]

Re: New Bizhub C8000 Printing quality big problem

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[Mick01]

Re: New Bizhub C8000 Printing quality big problem

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]

Re: New Bizhub C8000 Printing quality big problem

Can you say more about this modification ??

I tried the solution of paper.

slight improvement

[Mick01]

Re: New Bizhub C8000 Printing quality big problem

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]

Re: New Bizhub C8000 Printing quality big problem

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]

Re: New Bizhub C8000 Printing quality big problem

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

[djchampion]

Re: New Bizhub C8000 Printing quality big problem

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.

[djchampion]

Re: New Bizhub C8000 Printing quality big problem

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.

My plan is to ask in this matter. thanks for suggestion

[djchampion]

Re: New Bizhub C8000 Printing quality big problem

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

they tried.

yesterday service has changed lover transfer and upper. and first transfer barrel.

no effect

[kalindd]

Re: New Bizhub C8000 Printing quality big problem

they tried.

yesterday service has changed lover transfer and upper. and first transfer barrel.

no effect

Can you tell me, is this ( the defect) is on the lead edge, trail edge or on the side edge/edges?.
Correct me if I'm wrong, but it is on inner side (back of the machine) of the paper, am I right?

[djchampion]

Re: New Bizhub C8000 Printing quality big problem

Can you tell me, is this ( the defect) is on the lead edge, trail edge or on the side edge/edges?.
Correct me if I'm wrong, but it is on inner side (back of the machine) of the paper, am I right?

Yes Yes

the upper edge of print. Or as You say back side compare to machine look.

Please don't say that you know whats going on

[kalindd]

Re: New Bizhub C8000 Printing quality big problem

Tell your techs to open their Troubleshooting guide V5.0 and search for "Unevenness on edge".
There can be many reasons for this to happen.
I can assure you there is not an easy fix for this, it's combination of couple or more things.
Have they tried to swap the fusing unit? You say that you have 2 machines, this should be an easy task.
Like SCHWARZ suggested replace 1st fuser lower belt assy, fuser roller and external heater assy.

Choose
[Utility] -> [02 User Setting] -> [03 Common Setting] -> [Next] -> [Next] ->[Next] ->[Next] -> On Fusing stability priority choose "Image quality"

Have you tried to print with "Thin coated mode" activated?
[Utility] -> [02 User Setting] -> [03 Common Setting] -> [Next] -> [Prior Paper Type],[Thin Coated]
[Utility] -> [02 User Setting] -> [01 System Setting] -> [03 Paper Tray Setting] -> [81-105gsm Coated],select [Thin Coated] for the tray you want to use
in paper settings for this tray select CoatedGO and 81-105gsm. When you set this on the main screen you will notice small * that means that the function is active.
Choose different weight type.
I've read that you played with temps, but try this lower by 10 degrees only Fusing Roller Center Temp. (print) and (idle).

If none of mentioned above helps (but there should be some improvement) then:
Tell your techs to open their Troubleshooting guide V5.0 and search for "Unevenness on edge".

It can be as simple as, the sheet of paper enters the fusing unit skewed.
Make a panic stop and see whether the defect appears before the fusing unit ( is the image ok between the 2nd transfer and fusing unit)
Good luck.