conistent lines in cyan over whole page

[rafwagon]

KM C7000
I'm getting lines in cyan for over a week now. Always the same, identical lines. Only in cyan. Even after 1000 prints, nothing changes.

Drums have been swapped,
Developer (and unit) renewed.
Even the laser has been checked for foreign material.

edit: coronas also swapped, and the glass too

Has anyone ever seen this? How do i fix this?

[Synthohol]

did you swap corona units?

[rafwagon]

yes. coronas have been swapped too.

[blackcat4866]

Always cyan, and no other color?

[Ziggy]

swap the magenta and cyan developer units for testing. Just make sure to put tape over the toner supply hole on each developer unit and leave toner door open. Then run what would be a magenta test print and it will come out cyan. If it looks bad then chances are you have a bad developer unit. If cyan looks good then run what would be a cyan test print and it will come out magenta if it comes out bad then you have something in the cyan channel bad, only run one or two test prints.

[rafwagon]

Always Cyan, has been cyan from the beginning.

Develepor units have been replaced too

So i guess the laser is the only option left is too swap out the laser or something?

[blackcat4866]

I know that you said that you swapped the corona units, but that's what that defect usually points to: corroded primary grid. Install a new cyan corona unit.
Certainly it's possible that it could be the laser, but unlikely. The other thing I would look very closely at is the laser slit glass. Clean then very thoroughly with alcohol.

[Albonline]

where are the charge and bias setting at? this looks like grid blowout! are the anti misting systems working?

[rafwagon]

How do i check the charge and bias settings? Nothing has been altered. The I/O list where the charge can be checked (HV1) is marked 'do not use in the field'.

[wjurls]

Does it happen with internal test pages as well? Try running the density balance chart and see if it shows on it too. There is a bulletin out regarding defective SCSI cables connected from the fiery to the machine that can cause weird imaging issues on the C7000.

[rafwagon]

We run a CREO, not a FIERY
The problem is till not solved. I still shows on every page that uses Cyan. Also on test prints.
We did discover that the 1st stransfer DC BIAS for cyan is too high, double that of the otther colors (in drum peculuartiyt - auto gamma adjustment 0.

Any idea how we can get it down?

[blackcat4866]

Please, please, please start with a new corona unit. Stop trying to compensate for worn parts.

[rafwagon]

We are not trying to compensate for worn parts, all corona's and drums are new, we did that in the beginning of al the cyan problems, and again a week ago. . By now i'm pretty sure this problem won't get solved and maybe it's time for a new unit. Propably not KM this time...

[ps-tech]

We did discover that the 1st stransfer DC BIAS for cyan is too high, double that of the otther colors (in drum peculuartiyt - auto gamma adjustment 0.

Any idea how we can get it down?

Remove transfer belt unit and check 1st transfer roller. Swap with magenta and test again. Clean all rollers, reconnect all harness.

[rafwagon]

Thank you for the input, ps-tech. It didn't work though. We did that, and the same cyan issue wass still there. We even swapped the entire transfer belt unit with one from another machine, same cyan streaks. So no problem with the first transfer rollers. Now we are going to check all the wiring to the cyan developing unit and to the charging corona's. We alreaddy did a visual inspection of all contacts, but now it's time to take it apart. Last resort will be checking the pcrb. I know some are going to advice to replace the pcrb, but it's an expensive fix that might not solve the issue.