Mechanical Drive For Xerographics; Xerographic Control - Lexmark W820 Service Manual

7.
Discharge
At both the start and the end of each individual printer cycle the HVPS supplies the
BCR with an AC voltage that is used to electrically clean the drum. The AC voltage
removes any residual DC charge that was left from the previous print cycle.
At the beginning of each individual printer cycle the Printhead scans the surface of
the drum, further discharging any residual DC charge that may be left on the drum.

Mechanical Drive for Xerographics

The Drum Motor and the Main Drive Assembly provide the mechanical drive for the Drum
and the BTR.
The mechanical energy created by the Drum Motor is transmitted through the Main Drive
Assembly to a drive pin that is located at the rear of the Assembly. When the EP
Cartridge is in place, the Drum engages the pin. A gear attached to the end of the Drum
drives the BTR.

Xerographic Control

The logic on the MCU PWB controls all Xerographic functions. The High Voltage Power
Supply (HVPS) provides all of the Xerographic voltages.
HVPS
The I/O PWB supplies +24VDC to the HVPS. The HVPS converts the +24VDC to the
Xerographic voltages. The HVPS provides CR (Charge Voltages), DB (Developer Bias
Voltages), TR (Transfer Voltage), DTS (Detack Saw Voltage), and RTN (Return). The
logic on the MCU PWB uses a number of signals to the HVPS to switch on the various
Xerographic components.
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General Information