HP LaserJet 6L User Manual download pdf (Page 56)

Print Engine Control System

Laser and Scanner Drive

Based on information received from the Formatter, the DC Controller sends signals

to the Laser/Scanner Assembly to modulate the laser diode ON and OFF and to

drive the Laser/Scanner motor. Refer to “Image Formation System,” later in this

chapter for more information.

Paper Motion Monitoring and Control

The DC Controller PCA controls paper motion by continuously monitoring the

various paper sensors and coordinating the timing with the other print processes.

For a detailed explanation of paper movement, and the interaction of photosensors

and solenoid with the paper movement process, refer to the section “Paper Feed

System,” later in this chapter.

+12 V Shutoff Switch

The 12 volt DC power shutoff switch, Switch 101, located on the top of the printer,

is activated by the printer door. The front door must be closed before the printer can

resume printing.

Engine Test Switch

The Test Print, Switch 201, located on the DC Controller, is activated manually

through an access hole at the front of the printer. This switch causes the print engine

to perform a self-test diagnostic which bypasses the Formatter PCA and prints a full

page of black vertical lines. This test is useful for troubleshooting printer problems

because it isolates the print engine from the Formatter PCA. (See Chapter 7,

“Troubleshooting,” to learn more about how to perform an engine test.)

Motor

The Motor is controlled by the DC Controller PCA. The Motor provides all of the

printer’s paper movement.

Functional

Overview

Functional Overview 5 - 5

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HP LaserJet 6L User Manual Page 56