Lexmark X644E Service Manual - Page 200

7002-xxx Print quality-background Service tip: Some background problems can be caused by rough papers, non-Lexmark toner cartridges or if the media texture is set to the rough setting. Some slick or coated papers may also cause background problems. Some problems occur with printers that run a large amount of graphics in a humid environment. The customer may try to improve the print quality by increasing the transfer setting. Check the charge roll to make sure it is not at the end of life. FRU 1 Printhead 2 Transfer roll assembly 3 High voltage contacts 4 System board HVPS connector Action The printhead on this printer cannot be cleaned. Try another printhead if all other attempts fail to correct a background problem. Check the high voltage contact from the HVPS to the transfer roll. Check the transfer arm assembly right side bearing for contamination, pitting, or a loose cable to the bearing. If any problems are found, replace the defective part. Check the transfer roll shaft for contamination, wear, or pitting on the ends of the shaft that go into the bearings. If a problem is found, clean the ends of the shaft or replace the transfer roll assembly. Check the high voltage contacts on the right side frame to ensure they are clean and not bent, deformed, or pitted. If incorrect, replace the contact. Check the following voltages at J15 on the system board. Measure the voltages from J15 to printer ground. Pin J15 Voltage (approximate) Printer idle J15-1 0 V dc J15-2 +4 V dc J15-4 0 V dc Printer printing J15-1 0 V dc to +5 V dc J15-2 0 V dc to +4 V dc J15-4 0 V dc to +1.9 V dc If J15-1 voltage is incorrect, check the continuity of the front harness cable (J15-1 line). If there is no continuity, replace the harness cable. If there is continuity, replace the HVPS. If this does not correct the problem, replace the system board. If J15-2 voltage is incorrect or if the voltage remains at 0 V dc, check the continuity of the front harness cable (J15-2 line). If there is no continuity, replace the harness cable. If there is continuity, replace the HVPS. If this does not correct the problem, replace the system board. If J15-4 voltage is incorrect, check the front harness cable (J15-3 line). If there is not continuity, replace the harness cable. If correct, replace the system board. If this does not correct the problem, replace the HVPS. 2-162 Service Manual