Lexmark C750 Service Manual page 443

Look at the surface of each toner cartridge and check for a developed image.
Interpreting the results
If the developed images are not visible on one of the PC drums, the following components should be checked:
•
Toner cartridge - Switch cartridges to determine if the problem stays with the slot or cartridge.
•
Cartridge contact block pins - Verify that pins are spring loaded and properly positioned. See
contact assembly pin locations" on page 5-4
•
Developer HVPS cable - Make sure that there is no damage to the cable running from the system board.
•
Developer HVPS board.
•
System board.
If the image is well developed on the PC drum, but the same plane is missing or faded on the ITU belt, the
following components should be checked:
•
Bell cranks - Check the condition of the bell cranks.
•
Continuity on the bell crank circuit - Turn the printer off. Using a multimeter, check the continuity between
the rear bell crank contact for the failing color and the respective cable on the transfer HVPS board. See
"Transfer high voltage power supply (HVPS)" on page
•
Transfer HVPS cable - Make sure that there is no damage to the cable running from the system board to
the transfer HVPS board. Verify the connection at both ends.
•
Transfer HVPS board.
•
Engine board.
5-19.
Appendix A—Service tips
5060-00x
"Cartridge
A-17