HP Indigo press 3050 Troubleshooting Manual page 13

Troubleshooting Periodic banding
Troubleshooting:
1. Classify the Band grouping: (Single or Group).
2. Mark as many continuous bands as you can on the print sample.
3. Measure banding periods in millimeters (mm).
4. Calculate the banding frequency (in mm or Hz) - see calculation below.
5. Determine if the cause of the banding is mechanical or not:
•
Print 3 copies of the TS_1on_3off horizontal lines job, and the TS_1on_3off vertical lines job.
•
Note: The TS_1on_3off horizontal lines job is extremely sensitive to banding. Ignore any new
bands that may appear. At this stage ONLY focus on the specific banding identified on the
TS_Banding2 job, TS_Gray20 job and customer jobs.
•
Compare the two jobs:
Job comparison
Same banding appears at
the same frequency on both
jobs
Horizontal lines job:
•
Has specific banding,
but the vertical lines job:
•
None or much less
Inconclusive
Periodic banding frequency calculation
Notes:
•
Marking the bands:
•
In general, mark the bottom edge of bands (or group of bands).
•
Sometimes there is no clear edge. Mark the center of the bands (or group of bands).
•
Measuring the distance between bands (or group of bands).
•
Keep consistent - bottom edge to bottom edge, or center to center.
Steps:
1. Measure the distance between 1
2. Count the number of bands (or group of bands)
on the page.
3. Apply the formulas as follows:
Where:
F (mm) =
F (Hz) =
X =
N =
EN
Action
Determine the cause of the banding as follows:
Locate the banding frequency (that you calculated above) in
"Appendix 3 Periodic banding table – caused by gears and
rotating parts" on page 19.
•
•
Perform "Appendix 7 Optional alternative mechanical banding
diagnostic method" on page 25.
X
=
F ( mm )
−
N 1
1218
=
F ( Hz )
F ( mm )
Frequency in mm
Frequency in Hertz
st
Distance between 1 and last band
Number of bands (or groups) marked
and measured on the page
If table shows that the cause is a gear then:
Identify the gear using the "Appendix 2 Gear Transmission
Schemas" on page 18.
If the table shows that the cause is not a gear then:
Investigate the relevant component for possible defect or
malfunction.
st
and last band.
1
2
3
4
5
6
7
8
X
Banding troubleshooting 11