1.3.2 Paper Path Jam Detection Circuits
The paper path sensors monitor the progress of a sheet of paper through
the duplex paper path. The sensors are actuated by linkages that protrude
into the paper path and are deflected by the forward-moving paper.
Figure 1–9 shows the location of!the fixing unit exit,"inverter, and
#
second pass sensors. It also shows the duplex paper path, the rollers, and
the facedown fork gate.
Figure 1–9: Paper Path Sensor Locations
1
2
3
MLO-004931
The dc control board monitors the sensors during power-up and at specific
times during the print cycle. During power-up the fixing unit exit and
second pass sensors are checked. If either sensor detects paper, the printer
does not warm up, display READY, or go on line. The printer can be
powered up and display READY with paper in the paper path, but not
if the paper is under either sensor.
1–14 DEClaser 2200 Printer Service Guide
During the print cycle, the dc control board compares the timing and sensor
events to track the paper as it travels through the paper path. The print
cycle is initiated when a sheet of paper is fed into the paper path; the
cycle ends at the selected output stack. If the leading or trailing edge of
the paper fails to actuate a sensor within the expected time period, the dc
control board lights the control panel jam indicators, shuts down the fixing
unit heater, and causes the control panel beeper to sound.
The three jam indicators show the most probable location of a paper jam.
One sheet of paper can cause one, two, or all three indicators to light.
Figure 2–1 shows the three control panel jam indicators.
1.4 Electronic Block Diagrams
Figure 1–10 shows the major electronic components that operate the
DEClaser 2200 printer.
DEClaser 2200 Physical and Functional Description 1–15
Figure 1–10: 2200 Overall Block Diagram
Optical Fiber
Host
System
Control
Panel
Video
Control
Board
I/O
Board
DC
Control
Board
Laser/Scanner
Assembly
Laser
Diode
Scanner
Motor
HVPSA
Solenoid and
Sensor Board
Duplexing
Unit Motor
Primary
Corona/Grid
Bias
Transfer
Corona
Developing
Bias
Static Charge
Eliminator
Toner Sensor
Printer Unit
Sensors/Solenoids
Duplexing Unit
Sensors/Solenoids
Fixing Unit
Preconditioning
Exposure Lamps
LVPSA Main
Motor Driver
Power Switch
1–16 DEClaser 2200 Printer Service Guide
Main Motor
Safety
AC Driver
AC Inlet
MLO-004926
1.4.1 I/O Board
The I/O board can connect to a host system by a serial RS232C interface or
by a parallel 8-bit Centronics interface. Data passes directly through the
I/O board. See Section A.3 for pin-out and connector information.
NOTE: The switchpack mounted on some I/O boards is not used in the field.
The correct operational setting for both switches is open.
1.4.2 Video Control Board
The video control board receives commands and image data from the host
system through theI/Oboard. The image data is compiled into adotpattern
and stored in the page memory to be output to the laser scanner assembly
through the dc control board.
Figure 1–11 shows the major blocks of the video control board.
Figure 1–11: Video Control Board
A23-16
Expansion
ROM
Font
Cartridges01
Internal
ROM
M-CPU
AD15-0
GA2
GA1
MD
15-0
DRAM
EEPROM
S-CPU
MD15-0
I/O
Board
DC Control
Board
Control Panel
Indicators
Display
Keys
MLO-004912
• The main central processing unit (M–CPU) is a 32-bit microprocessor
that controls all activity on the video control board.
• The subcentral processing unit (S–CPU) is a 16-bit microprocessor that
operates as a slave to the M–CPU.
DEClaser 2200 Physical and Functional Description 1–17
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