HP Latex 2700 User Guide 3 - Page 286

To check printhead alignment, print the printhead-alignment verification plot see

Page 286 highlights

- Run the diagnostics to check that the substrate-advance sensor is not dirty. If the substrate advance is not well adjusted, particularly if it is under-advancing, a dark line can appear between passes. A clear symptom of this is when the dark lines appear across all colors, because the cause is common to all of them. To confirm it, see Substrate-advance verification on page 137. You can usually correct this problem by adjusting the substrate advance compensation (see Substrateadvance compensation on page 134). However, you are recommended to run the OMAS Diagnostic Tests from the maintenance 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 174. Thin white lines These are thin white/light lines across the entire image at regular intervals, more easily seen in solid area fills. There are three likely causes: ● Nozzle clogging. A printhead nozzle can be sealed temporarily, by some fibers or dirt in the ink bore. Then not all the ink is fired and a lighter horizontal band appears. Sometimes a bigger drop with all the accumulated ink appears at the end of this light thin line, meaning that the bore is clear then. See Printhead-health troubleshooting on page 294. ● Printhead alignment. This is a clear contributor to banding. If printheads are not correctly aligned, the misplaced dots could correlate directly with the severity of the banding, by leaving lighter bands where the ink should have been placed. To check printhead alignment, print the printhead-alignment verification plot (see Manual alignment procedure on page 127). As a general rule, the biggest contributors to thin-white-line banding caused by printhead alignment: - Inter-color alignment (alignment between different colors) Here are some tips for solving this problem: - Perform printhead alignment. There is no need to repeat the alignment at each white position: the correction is preserved despite moving the white printhead along the movable slot system. - If the printhead alignment was done with a different substrate of different thickness, probably a new printhead alignment is needed. ● Substrate advance. Before trying to adjust any parameter, make the following checks: Thin white lines 279

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Run the diagnostics to check that the substrate-advance sensor is not dirty.
If the substrate advance is not well adjusted, particularly if it is under-advancing, a dark line can appear
between passes.
A clear symptom of this is when the dark lines appear across all colors, because the cause is common to all
of them. To confirm it, see
Substrate-advance
verification
on page
137
.
You can usually correct this problem by adjusting the substrate advance compensation (see
Substrate-
advance compensation
on page
134
). However, you are recommended to run the OMAS Diagnostic Tests
from the maintenance 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
174
.
Thin white lines
These are thin white/light lines across the entire image at regular intervals, more easily seen in solid area fills.
There are three likely causes:
Nozzle clogging.
A printhead nozzle can be sealed temporarily, by some fibers or dirt in the ink bore.
Then not all the ink is fired and a lighter horizontal band appears. Sometimes a bigger drop with all
the accumulated ink appears at the end of this light thin line, meaning that the bore is clear then. See
Printhead-health troubleshooting
on page
294
.
Printhead alignment.
This is a clear contributor to banding. If printheads are not correctly aligned, the
misplaced dots could correlate directly with the severity of the banding, by leaving lighter bands where the
ink should have been placed.
To check printhead alignment, print the printhead-alignment verification plot (see
Manual alignment
procedure
on page
127
). As a general rule, the biggest contributors to thin-white-line banding caused
by printhead alignment:
Inter-color alignment (alignment between different colors)
Here are some tips for solving this problem:
Perform printhead alignment. There is no need to repeat the alignment at each white position: the
correction is preserved despite moving the white printhead along the movable slot system.
If the printhead alignment was done with a different substrate of different thickness, probably a new
printhead alignment is needed.
Substrate advance.
Before trying to adjust any parameter, make the following checks:
Thin white lines
279