Riso MZ790U Instruction Manual page 251

Problem
The unwanted background of
an original is picked up on
copies.
Dirt is found on printed copies. The Stage Glass (and/or the ADF
The edges of printed copies
are smudged with ink.
The back of the printed paper
is smudged with ink
Possible Cause
If newspaper or colored paper is used
as an original, the background is
picked up on copies.
Scanner Glass) is not clean.
Larger size of paper than the original
was placed on the Paper Feed Tray
at the time of the master-making
process.
Did you use [Max. Scan] setting when
making the master?
When printing thick paper such as
cards, corners of the paper contacted
and damaged the master.
The Pressure Roller has been stained
with ink.
The Feed Tray Paper Guides were
not fit to the width of paper at the time
of the master-making process.
Are you using a paper that does not
efficiently absorb ink?
Action
Lighten the "Contrast" and create a new
master.
"p.75
Clean the Stage Glass (and/or the ADF
Scanner Glass).
"p.228
Because a master was made according to
a larger size than the original, the edges of
the original were processed as shadows.
Set the same size of paper as the original
and perform the master-making operation
again. Or attach tape as described below
to solve the problem.
Make another master and print with the
new master. Or pull out the Print Cylinder
(Drum) and attach cellophane tape to the
damaged section on the master. However,
if attached with cellophane tape, a master
may not been properly sent to the Master
Disposal Box.
Remove the Print Cylinder (Drum) and
clean the Pressure Roller.
"p.228
If the print position is outside the print
paper, this may cause the Pressure Roller
to be stained with ink.
Be careful when changing the size of print
paper or shifting the print position.
Adjust the Feed Tray Paper Guides to the
width of the paper.
If the Feed Tray Paper Guides are set
wider than the width of the paper, a master
will become wider than necessary.
"p.31
The ink did not dry fast enough, marking
onto the reverse side of the next paper.
Either change the paper or try "Ink Saving"
or "Interval" features.
"p.84
"p.120
Troubleshooting
251
Troubleshooting