GR3770 marking underside of prints

[mrjonolewarne]

Hi,

My gr3770 (probably the most problematic riso every made judging by the frequency of my posting on this forum) is marking the underside (non-printing side) of my prints.

On the right side of each print, about 20mm in from the right hand edge of the sheet, are two small identical marks, one at the top of the page, and another further down.

I've tried making new masters, cleaning the pressure roller and even a different drum, looking around the drum for ink deposits, but the problem persists.

I've had a similar problem before when printing in high numbers towards the end of runs, where ink creeps up to the edge of the master sheet and transfers to the underside of prints, but this isn't happening this time and occurs right from the first print.

I'm in a rush to print a very important job for a hugh client of mine so any help on this would be amazing!

Thanks

[mrjonolewarne]

I seemed to have diagnosed the problem:

I looked carefully over the drum and found a pin-prick where ink was coming through, transferring to the roller, which transferred to the underside of the sheet.

I cured it by putting scotch tape over the whole.

I'm not sure how this has happened, or why it's started now.

I was printing A4 sheets, which is why the ink transferred to the roller instead of the sheet, which I guess is what will happen the next time I print on A3.

What could be causing the pin-prick on all of my drums? I guess it's something occurring in the master-making process. I check the glass and it's clear.

Has anyone had anything similar happen to them?

[RRodgers]

I seemed to have diagnosed the problem:

I looked carefully over the drum and found a pin-prick where ink was coming through, transferring to the roller, which transferred to the underside of the sheet.

I cured it by putting scotch tape over the whole.

I'm not sure how this has happened, or why it's started now.

I was printing A4 sheets, which is why the ink transferred to the roller instead of the sheet, which I guess is what will happen the next time I print on A3.

What could be causing the pin-prick on all of my drums? I guess it's something occurring in the master-making process. I check the glass and it's clear.

Has anyone had anything similar happen to them?

Too much ink on the lead adge will cause it to wrap, or could cause the pick off finger to hit the drum/master. But you did say it was only on one side. Hmmm

[Iowatech]

If the pin pricks are in identical positions, it is probably dust under the glass, or maybe even on the scanner mirrors. Or the machine might be "system blotto" from a power surge or something that put bad data on the machine's operating memory, that can cause all manner of undesirable operation. So try a memory clear.