Optical Skew bizhub C6000

[blackcat4866]

So, I've got an optical skew affecting all colors in the crossfeed direction of 1.5mm. In the feed direction it stays pretty consistently without skew. Naturally, it's most noticeable when duplexing, since the lines seen through the paper appear twice as skewed.

I've found this little tidbit in the service manual:
To correct this skew, adjust the skew of the G5 lens of the write unit /K.
Perform this adjustment manually using the following menus:
"Both Sides Adj."
"Chart Adjustment" of the user mode
"Machine Adjustment > Printer Adjustment > CD-Mag. Skew Adjustment"

The C, M, and Y, can be adjusted automatically or individually, but in reference to the black write unit /K. "CD-Mag. Skew Adjustment" moves a total of 0.6mm, about 1/3 of the correction I'm looking for (if it worked, and doesn't). So after all that, how do you adjust the G5 lens of write unit /K? =^..^=

[blackcat4866]

bump. =^..^=

[Woxner]

thats funny i never seen an optic skew affected by laser unit... dont you mean you have a skew in the machine and not optics?

[blackcat4866]

The laser is an optical device. The problem presents on internal prints, so clearly it isn't scanner optics, it's a laser adjustment.

As opposed to a paper skew. =^..^=

[D_L_P]

The laser is an optical device. The problem presents on internal prints, so clearly it isn't scanner optics, it's a laser adjustment.

As opposed to a paper skew. =^..^=

Optical skews are the worst. Especially because it is easy to go past 'square' and skew the other way.
If .6mm isn't gonna get you there, maybe there is a mechanical adjustment for the PH?
If nothing else maybe forcing a shim would get you close enough that the .6mm would work?

[blackcat4866]

Optical skews are the worst. Especially because it is easy to go past 'square' and skew the other way.
If .6mm isn't gonna get you there, maybe there is a mechanical adjustment for the PH?
If nothing else maybe forcing a shim would get you close enough that the .6mm would work?

Since the black laser is my reference, my fear is going back down that road of beam detect errors, that I fought with last year. Since this customer is billable, I'll present it as an option (a dangerous option).
=^..^=

[blackcat4866]

... So after all that, how do you adjust the G5 lens of write unit /K? =^..^=

Anybody else? I find it interesting that the manual tells what you need to do, just not how to do it.

[Synthohol]

have you tried swapping drums? only because if even some developer is stuck in the drums contact points of the process unit it can make a trapezoid kind of thing.
did you try the "both sides adjustment?" i have an 18" clear scale (ruler for the novice ;) )that knocks this out in no time.
remember to zero out the adjustment prior to printing the test pattern.
you probably know this but i typed it for the greenhorns.

[blackcat4866]

I kinda doubt that it's the drum, mostly because this machine has been through 5 black drums in the last year, and the optical skew has not changed. It's a thought though.

I have not looked into the paper tray settings > Both Sides Adjustment. Now that you mention it, there may be a skew adjustment there.

A complicating factor here is multiple techs approaching this task differently: some as a paper skew, some as an optical skew, some as a scanner skew. The first thing that I discovered is the plastic aligning bracket under the front of the fuser was barely attached, hanging from the last few threads of one of the screws. Each time the lower duplex door closed, it landed in a slightly different spot. Most of the painted-screw adjustments for that door have been moved around and many of the screws loose, so I have no real idea where it should be. The paper seems to travel a fairly straight path now though.

Thanks for your thoughts. =^..^=

[Synthohol]

the b/s adj should correct for trapezoid that masks itself as skew as well.

[JR2ALTA]

isn't 1.5mm within spec?

[blackcat4866]

Not for a print shop. =^..^=