Overprinting Pre-Printed Sheets on iGen4

Hi there,

Struggling with a job at the moment where I am trying to print a code on some pre printed litho sheets. The sheet is black all over with a few white boxes where the code goes.

Started off not too bad and ran nearly 300 sheets no problems, but then really struggled. Now it prints 1 sheet before jamming and the 2nd sheet always stops in area 2, also the paper tray lowers and says its jammed but theres nothing there. I've tried different trays, stock settings and cleaned the glass in area 2.

Starting to think that the sheet being black edge to edge isn't helping but it still baffles me that it ran 300 sheets to begin with!
Does anyone have any ideas? Supposed to have run 20,000 sheets for Monday *Facepalm*

 

Have you got a strip of colour bars on the outboard edge? Had exactly the same problem at a new customer in Basingstoke. Full coverage pre printed with a colour bar along the long edge. Rotated the job and sheet and it ran all day long then. Any print the reg entrance sensor sees confuses it and thinks it is the wrong size. The detector is on the upper part of the sensor and gets reflected light from the change in density

If the black is 3mm edge to edge you may have to rethink the job and get the pre print done again on slightly wider paper to move the print away from the edge

Can I also advise that you use minimum offset dust as this quickly contaminates the sensors, transports and fuser

--
Mark

 

The black goes all the way to the edge unfortunately. I'll try cleaning the sensors again in the morning and give it another go. Thanks for the tips Mark.

 

Need to replace the jam sensors up to area 2. The sensors are optical and can't read the difference between the lead edge of sheet and no sheet at all. The sensors were probably marginal at first. There might be more marginal sensors down the line also. Check all the registration sensors in diags on psip make sure they are reading low values.

 

that should be fixable....what if you print a front side that is all black, then when it goes back through...i do that regularly.

im with milo on that one. sensor must be just off enough, then the black is causing problems...

 

Had the job re-printed with a white boarder around the edge this time. Has been running like a dream all day.

Although interesting about what you guys said about the sensors, may get them looked at next time an engineer is around.