Printhead Control - Lexmark W820 Service Manual

4025-XXX

Printhead Control

The Laser Diode PWB controls laser power monitoring and adjustment. The MCU PWB
controls the rest of the Printhead Assembly functions. The ESS PWB processes video
data sent from a host computer. The ESS PWB then passes that data on to the MCU
PWB which controls the flow of video data to the Laser Diode PWB. The MCU PWB
switches the laser diode on and off according to the image data being sent from the ESS
PWB. When the data signals for a black pixel, the MCU PWB rapidly switches the Laser
Diode on and off.
The MCU PWB provides the +5VDC needed to drive the Laser Diode. The CRU Interlock
Switch cuts +5VDC to the Laser Diode when the EP Cartridge is not in place in the
printer. The MCU PWB provides the +24VDC needed to run the Printhead Motor. The
MCU PWB also provides the signal (/RMOT ON) that switches the Printhead Motor on
and off. To reduce Printhead Motor wear, the MCU switches off the Printhead Motor after
15 minutes of printer inactivity.
The MCU PWB provides the +5VDC (signal 5V) needed by the SOS Sensor. The Sensor
uses the /SOS signal to return information about the start of each scan to the MCU PWB.
1-50
Service Manual