HP Laserjet 5 Service Manual

Static Eliminator Teeth (located in front of the transfer roller)
Cleaning Spilled Toner
Defective toner cartridges can develop leaks. In addition, after a paper jam has
occurred, there may be some toner remaining on the rollers and guides inside the
printer. The pages that print immediately after the jam may pick up this toner.
Clean spilled toner with a cloth slightly dampened in cold water. Do not touch the
Transfer Roller with the damp cloth or with your fingers. Do not use a vacuum
cleaner unless it...

5
Functional Overview
Contents
Basic Printer Functions .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 5-3
DC Controller/Power System . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 5-4
Print Engine Control System .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 5-5
Power System (on DC Controller PCA) .  . .  . .  . .  . .  . .  . .  . .  . .  . . 5-6
Formatter System . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 5-8...

5 - 2 Functional Overview 

Basic Printer Functions
This chapter presents a generalized functional overview of the printer and the
printing processes. The following printer systems are discussed:
·DC Controller System/ Power System
·Formatter System
·Image Formation System
·Paper Feed System
·Laser/Scanner System
Figure 5-1 is a generalized block diagram of the printer:
Printer Functional Block Diagram
Figure 5-1
5
Functional
Overview
Functional Overview 5 - 3 

DC Controller/Power System
The DC Controller PCA coordinates all print engine activities, drives the laser, and
coordinates print data from the Formatter PCA with the image formation process.
The DC Controller also includes both AC and DC power supply and distribution
circuitry. The DC Controller controls the following systems and functions:
·Print Engine Control
·Laser and Scanner Drive
·Paper Motion Photosensors (Paper Out, Paper Registration, and Paper Exit
Sensors)
·Motor
·Power System
·AC Power...

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...

Power System (on DC Controller PCA)
The AC, DC, and high voltage power supply circuits are all contained within the DC
Controller PCA.
AC Power Distribution
The AC power circuitry supplies AC voltage whenever the power cord is connected
to the AC power source. AC voltage is distributed to the DC power supply circuitry
and to the AC driver circuitry, which controls AC voltage to the fusing assembly’s
heating element.
DC Power Distribution
The DC power distribution circuitry, located on the DC Controller...

The printer exits SleepMode and all of the lights power on when any of the
following occur:
·A job is received.
·The Front Panel Button is pressed.
·The printer front door is opened.
NoteThe printer will not enter SleepMode if there is a printer error.
High Voltage Power Distribution
The High Voltage Power Supply PCA applies an overlap of DC and AC voltage to
the primary charging roller and the developing roller. This circuit also applies a
positive or negative DC voltage to the transfer charging roller...

Formatter System
The Formatter PCA is responsible for the following:
·Receiving and processing print data from the printer interface.
·Monitoring Front Panel Button and relaying printer status information.
·Developing and coordinating data placement and timing with the print engine.
·Storing font information.
·Communicating with the host computer through the Bi-Directional Interface.
The Formatter PCA receives print data from the Bi-Tronics Interface and converts it
into a dot image. The DC Controller...

Control Panel
Status LED Lights
The Formatter uses three LEDs mounted under the printer cover to communicate
printer status to the user. Refer to “Using the Control Panel” in Chapter 3 and
“Printer Error Troubleshooting” in Chapter 7 for more information on the lights.
Front Panel Button
The Formatter PCA is connected to a microswitch located on the control panel
PCA. The single button is used for such functions as self test, reset, and to display
error codes. Refer to “Using the Control Panel” in...