HP 750c Service Manual - Page 194

750C Pattern 3 (on the CAD color diagnostic pot) contains vertical and horizontal lines of the four 750C Plus 755 basic colors (cyan, magenta, qualitative information. yellow and black). This is a worst case situation, which provides CM Pattern 4 (on the CAD color diagnostic pot) includes one square and horizontal and vertical lines in red (yellow plus magenta), blue (cyan plus magenta), and green (yellow plus cyan). The horizontal and vertical lines can be used to verify whether the alignment between the cartridges used to print them is within the required specification. The lines are one pixel in thickness. If the plot is printed on matte film" media the dot size is approximately 3.33 mils diameter (the same value as the alignment specification). Focus on one horizontal or vertical blue line (see figure below), that is generated by two lines of cyan and magenta. If there is a misalignment between the two cartridges, bigger than 3.33 mils, the lines will be this distance apart. In this case, there will be a white line between the magenta and the cyan, as the dots of each color will not come in contact. (The distance will be bigger than the dot size.) When there is a blue line between the magenta and the cyan, then the distance between the lines is smaller than 3.33 mils, hence, the alignment error is within the required specifications. Alignment error 3.33 mils In Spec (limit) Dot size 3.33 mils (Film / Glossy) Alignment error < 3.33 mils Out of Spec Corrective Actions If the penĆtoĆpen alignment error is out of specification: D Perform the pen alignment test using white media ' page 8Ć40. D Perform the lineĆsensor calibration (details ' page 7Ć5) and perform the pen alignment test again. D Replace all cartridges. D Replace the carriage ' page 6Ć34. D Troubleshoot the EEROM and the Main PCA. 9-16 Print Quality C4705-90000