●
Substrate advance. If the substrate advance is not well adjusted, particularly if it is over-advancing, a
white line can appear between passes.
A clear symptom of this is when the white lines appear across all colors, because the cause is common
to all of them. To confirm it, in the Internal Print Server, select Printer > Advance Calibration to check
the substrate advance. See
Substrate-advance test print on page 107.
You can usually correct this problem by adjusting the substrate advance compensation (see
Substrate-
advance compensation on page 106). However, you are recommended to run the OMAS Diagnostic Tests
from the Print Care window as soon as the substrate is unloaded, to avoid having the same problem
with other substrates. See
Clean the substrate-advance sensor on page 178.
If the problem persists, try adjusting tension and vacuum settings according to the table below, step by
step (a to c), until you find settings that work.
●
Printhead alignment. This is a clear contributor to banding. If printheads are not correctly aligned, the
misplaced dots could correlate directly to the severity of the banding, by leaving lighter bands where
the ink should have been placed.
To check printhead alignment, print the printhead alignment diagnostics plot (see
Printhead alignment
diagnostics plot on page 101). As a general rule, the biggest contributors to thin-white-line banding
caused by printhead alignment are (in this order):
◦
Intra-color alignment (alignment between the two printheads of the same color)
◦
Inter-color alignment (alignment between different colors)
Here are some tips for solving this problem:
◦
If the printhead alignment was done with a different substrate of different thickness, probably a
new printhead alignment is needed.
◦
If the problem comes from an automatic printhead alignment, you can try manual alignment for
better control of the alignment process.
◦
If the problem comes from a manual alignment, fine-tune it by identifiying the offenders in the
printhead alignment diagnostics plot. See
Manual alignment on page 98.
Bands of light and dark zones
These are periodic horizontal bands formed of a lighter band and a consecutive darker band. This pattern is
mostly seen in solid color area fills (such as light purple or gray).
236 Chapter 10 Troubleshoot print-quality issues ENWW
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