HP Designjet 250c Service Manual - Page 193

VerticalĆLine Straightness (VLS) Symptoms VerticalĆline straightness is a measure of the horizontal distance between the segments of a vertical line plotted in two consecutive swaths. If the plotter is working correctly, this distance should be less than 2 mils. (PrintĆQuality Plot ' page 8Ć56 3. - VLS.) (See also ' User's Guide, chapter 4.) Swath Printing Direction Swath (n-1) Swath Printing Direction Swath (n) Swath Printing Direction Swath (n+1) Maximum allowable VLS Error = 2 mils. Swath Swath Swath Swath Width Width Width Width Depending on the causes of the error, lines that are supposed to be vertical may appear as shown below: 1 2 3a 3b 4a 4b Carriage Swath Direction 1 No error 2 Bidirectional error 3a Theta-Z error 3b Theta-Z error 4a Combined error 4b Combined error Customer Expectations Although the VLS specification satisfies the expectations of most customers, some may complain even when the plotter is working within this specification. If the VLS error is already less than 2 mils, do not try to improve it. Bidirectional Error Error numbered 2 above is called a bidirectional error. If you print the same plot using a unidirectional print mode, the error should not appear. (Print modes ' chapter 5.) This error can occur for various reasons, including: D Incorrect distance between nozzles and media. (Adjustment ' chapter 7.) D EncoderĆstrip slots are damaged or dirty. D Dirt on the pulley is causing the belt to slip. D Friction between carriage bushings and slider rod: 230 250C (See ' Error code Steady 346.) 330 350C (See ' Error code Steady 234.) C4699Ć90000 Troubleshooting 8Ć59