Service manual

84 Theory of operation ENWW
Introduction
This chapter presents an overview of the relationships between major components of the
HP LaserJet 2300 printer. The following systems are discussed:
● engine control
● laser/scanner
● image formation
● pickup and feed
● formatter
Basic sequence of operation
Operation sequences are controlled by the CPU in the engine controller PCA. Table 19 describes
engine operations for each period of a print operation.
Table 19. Basic sequence of operation
Period Timing Purpose Remarks
WAIT (wait period) From power-on until
completion of the main-
motor initial drive.
Clears the drum surface
potential and cleans the
transfer charging roller.
Detects whether or not
the cartridge is installed.
Also, during WAIT, the
LEDs cycle and the
HP logo appears on the
control-panel display.
STBY (standby period) From the end of the WAIT
period until the print
instruction command is
received from the
formatter, or from the end
of LSTR until the print
instruction command is
input from the formatter,
or until the power is
switched off.
Maintains the printer in a
ready state.
INTR (initial rotation
period)
From receipt of the print
instruction command
from the formatter until
the media reaches the
top-of-page sensor.
Stabilizes the sensitivity
of the photosensitive
drum in preparation for
printing.
PRINT (print period) From the end of INTR
until 0.8 seconds after
the top-of-page sensor
detects the trailing edge
of the media.
Forms an image on the
photosensitive drum
according to instructions
from the formatter and
transfers the image to
media.
LSTR (last rotation
period)
From completion of
printing until the main
motor stops rotating.
Delivers the final page
out of the printer and
cleans the transfer
charging roller.
If a print instruction
command is received
from the formatter, the
printer bypasses WAIT
and STANDBY and
immediately enters INTR.