Xerox 7665 - Streak In Process Direction - Black and Cyan

[chrisban35]

Ok, I'm having some fun with this 7665. Pic has streak in process direction and its TEXTBOOK image of the Figure 1 on page 423 (PDF Reader)... Illustration can be found immediately by using search and typing in "Streak deletion Defect Sample".

Has new black drum, new IBT belt and new Black Developer unit.

IBT is working perfectly, Developer and drum no defects or problems..

According to the service manual next step is to start just replacing a bunch of boards... I don't have a spare machine to do this, and not wanting to just start replacing boards...

I am turning to the most valuable resource there is... Other technician's experiences with this type of problem..

Thanks in advance for any help with this very bizarre streak problem...

My guess is potentially the ROS which controls C and K but, want to make sure I bounce that against the fine depth of experience on this site first..

[chrisban35]

Just FYI.. it is the Black primarily not showing up at all in the streak. But the Cyan is also very very light and not saturating the proper amount of fill on the page down the same exact streak. The streak is probably less than 1/4" and the two outsides are darker and in the middle it goes to totally missing the black and very very light with Cyan.

If I print out a true black copy, the space is completely white. If I print out process black, then you can see the yellow and magenta in the center, but not the black.. and very light hew of Cyan.

Running the individual colors, you can see that Magenta and Yellow work perfectly fine. Cyan you can see the streak but its light to medium in influence in the solid page fill.

Black, is completely white on solid page fill in that streak that follows process...

Just FYI....

[Exok]

It sound to me like you have something blocking your laser unit window. I would remove the drum / dv tray off its rails, remove the IBT assembly and take a look at / clean the laser unit windows for black and cyan. The laser has to reach the drum to discharge the print area to attract toner. Blocking the laser will result in a void area in the process direction lead to trail edge. If cleaning the windows does not help, it may be possible that toner dust has entered the laser unit and the mirrors / lenses inside the unit are dirty. The machine uses 2 laser units. Black and Cyan share one unit.

[chrisban35]

Thank you for taking the time to reply.

I was suspect of that at first too, until I realized that it is a perfect line for both black and Cyan. Usually if its debris blocking multiple drums, it will be in separate lines... But since both lines are exactly on top of one another, I was thinking it sounded more like a ROS?? What is your take on that assumption?

I cleaned out the imaging units really well, and the IBT belt is brand new, and I cleaned the IBT assembly with great attention to detail. So I'm still wondering what else in the imaging process could be causing two colors to act almost identically the same??

Again, thanks for taking the time to reply. I sincerely appreciate your input.

[chrisban35]

I forgot to respond to you on the laser units.. Yes, I believe that is possible. I did not check those yet.. When I arrive onsite today, that will be one of the areas I concentrate my efforts on. Thanks again..