HP Designjet 2800/3800cp Service Manual - Page 150

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) Primary Color Components Magenta (M) and Yellow (Y) Magenta (M) and Cyan (C) Cyan (C) and (Y) The main causes of banding are due to: D Printheads. D Media advance. 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 HP DesignJet CP Series Printers Image Quality