Can not adjust image vertically on #4 yellow unit

We can not seem to adjust the vertical position of the image on the 4th (yellow) unit. We input a value of 40 and the image moved very little.

Has anyone have any suggestions?

 

Where are you making these adjustments? In the regular operator register screen or in the service function screen? In the operator screen a move of .40 is 4/10ths of a mm. In the service function screen a move of 40 is hardly noticeable.

 

I believe we are making this adjustment in the regular screen, It seems to be okay now after we set it back to .8 So I not sure if we have a problem. Any suggestion for eliminating double imaging from the 1st unit black ink on tail end of sheet usually on 12x18" 80lb coated.

Thanks for your help

 

I normaly reduce pressure and ink.. it helps with doubling

 

Doubling on the first unit is from the feeder. One of the biggest issues that causes this is the infeed brushes. If they are worn it will not hold the sheet down properly causing the tail to whip.

The next problem and probably the main problem is the infeed wheels themselves. These are never to be adjusted, yet people still try. The wheels have specific touchdown and lift off times as well as dwell settings in order to be on the paper until the sheet is firmly held by the grippers. These settings have to be made by an experienced technician with the proper dial indicators. Anyone who tells you they can do it without the proper tools is not doing it correctly.

There are also backlash settings that need to be checked in the gears which drive the feeder if the aforementioned items do not stop the doubling.

Another trick to lessen the doubling is to put yellow in the first unit then run K, C, M. Typically the doubling in the yellow is not as noticeable. This is a temporary workaround until you can have someone come out to look at your feeder.