HP 8550mfp Service Manual - Page 164

Cleaning roller control The controller board activates the cleaning roller press solenoid (SL1). SL1 presses the cleaning roller to the transfer drum just after the secondary transfer begins. When the SL1 signals on, the cleaning roller press cam presses the cleaning roller, and the cleaning roller presses against the transfer drum. When the transfer drum cleaning and secondary transfer are complete, the controller board sets the SL1 off to detach the cleaning roller from the transfer drum. Figure 42. Cleaning roller control Carousel control The controller board controls the rotation speed and the stop position of the carousel by monitoring the timing of the eight flags that pass through the carousel position sensor (PS3). The rotation position flags are located on the back side of the carousel. The eight rotation position flags consist of the home position flag (also the black toner 162 Chapter 5 - Theory of operation EN