HP DesignJet 2500CP Service Manual page 144

One of the most common problems that affects the overall image quality is
`Banding'.
Banding Problems
Banding is when you see repetitive horizontal bands within the printed image
(these may appear as light or dark bands).
Test pattern 2 is printed with four primary colors; black, cyan, magenta and
yellow. The three secondary colors printed are; red, blue and green which are
composed by mixing the primary colors as shown in the table below:
Secondary Color
Red (R)
Blue (B)
Green (G)
The main causes of banding are due to:
Printheads.
D
Media advance.
D
Banding Caused by Printhead Problems
If test pattern 2 has clear or dark horizontal bands in one or more of the
primary color columns, then several of the secondary color columns will also
have the same type of bands in the same position (but perhaps with less
intensity).
These bands are caused by two types of printhead nozzle failure; either
nozzles not printing, or nozzles misdirected. For further information on
printhead nozzle failures, refer to Test Pattern 3 ' page 6 13.
In the following Example A, several nozzles in the magenta printhead are not
printing. There will be clear repetitive bands (perhaps white) in the magenta
column. Consequently, you will see lower intensity bands in the same print
position in the red (M + Y) and blue (M + C) secondary color columns.
6-8
Primary Color
Components
Magenta (M) and Yellow (Y)
Magenta (M) and Cyan (C)
Cyan (C) and (Y)
HP DesignJet CP Series Printers Image Quality