Lexmark T642 Service Manual - Page 160

4061-xx0 Print quality-black bands on outer edges of the page This print quality problem appears as vertical black bands on one or both sides of the copy and can be wide, narrow, light, or dark. FRU 1 Charge roll counterbalance springs 2 Charge roll assembly Charge roll link arm 3 HVPS Action If the problem is just on one side of the page, check the charge roll counterbalance spring on that side. You can check to see if enough force is being applied to the charge roll by applying slight downward pressure with your finger to the charge roll link arm that the spring is attached to while you run a print test sample. See if the problem changes or goes away. If this fixes or changes the problem, then check the springs and charge roll link arm assemblies for binds or defective parts. Replace as necessary. Check the charge roll for toner buildup or other contamination on the outer edges that correspond to the bands on the page. Check the charge links and arms for proper operation, binds or incorrectly mounted counterbalance springs. Repair or replace as necessary. Check the following voltages at J15-8 on the system board: • Printer Idle J15-8 measures 0 V dc • Printer Printing Test Page J15-8 voltage changes from 0 V dc to +4 V dc If the voltage does not vary, check the continuity of line J15-8 in the front cable harness. If there is no continuity, replace the cable harness. If there is continuity, replace the HVPS. If this does not correct the problem, replace the system board. Turn the printer off, and check the resistance between J15-7 and printer ground. The resistance measures approximately 0 ohms. If incorrect, make sure the system board is mounted correctly and securely grounded. If correct, replace the system board. Print quality-residual image Service tip: Install a new print cartridge if available before doing this service check. Residual image can be caused by the photoconductor, cleaning blade, and other parts inside the print cartridge. FRU 1 Hot roll fuser assembly Action Check the fuser assembly for toner contamination. The hot roll especially might cause toner to be retained and deposited on the page. 2-120 Service Manual