[CQ] MP C6502 Shading Issue

[Alear]

I have attached an image with detected SC codes. I suspect the laser unit or the mag roller. Wandered if anyone else has run into this issue also. In past we replaced the charge and charge board (Y), developer (Y), and potential sensor (Y). It resolved the issue for about 5 months and has returned. Thanks in advance.

[slimslob]

Re: MP C6502 Shading Issue

Check the PCUs. Odds are that someone has disconnected the lube bar sensors and the lube bars are completely gone. After the lube bars wear too far, the cleaning blade is not able to fully remove toner from the drum surface which is then removed by the spreader blade. Toner builds up between the 2 blades and eventually neither blade is able to clean the drum surface. Toner built u p between the blades is then applied to the drum surface causing back ground. PM all PCU cleaning stations. If you are lucky, you have not damaged the drums.

[Alear]

Thanks for the reply. I checked with previous tech and he rebuilt the cleaning unit. The old bar was low but not empty. Sensors were and are connected.