Xerox Phaser 4500, Service Manual

Page: 66 / 537

Theory of Operation 2-31
Electrical
24 V Interlock This safety switch interrupts 24 VDC from the LVPS to the HVPS/
Engine Logic Board and Main Motor when the Top Cover is open. This switch
operates in series with the Rear Cover Switch. See “Schematic Diagram of Power
Distribution and Interlocks” on page 2-33.
5 V Interlock This safety interrupts 5 VDC power from the LVPS to the LD
Assembly of the Laser Assembly when the Top Cover is open. This interlock works in
series with the Laser Interlock. See “Schematic Diagram of Power Distribution and
Interlocks” on page 2-33.
Rear Cover Switch
This safety switch interrupts 24 VDC from the LVPS to the
HVPS/Engine Logic Board and Main Motor when the Rear Cover is open. This
switch operates in series with the 24 V Interlock. See “Schematic Diagram of Power
Distribution and Interlocks” on page 2-33.
Main Fan This vents air inside the printer to prevent an excessive rise in the inside
temperature.
Sub Fan This fan takes outside air into the printer to prevent an excessive rise in the
inside temperature. This is mounted near the Laser Assembly in the center on the
front side.
LVPS
The Low Voltage Power Supply provides 5 V and 3.3 V for Logic Circuits, 5 V
for the Laser Diode, and 24 V for Motors and Clutches.
HVPS/Engine Logic Board The functions of the HVPS and engine controller are
brought together on a single circuit board. The HVPS provides high AC and DC
voltages to the BCR (charging), Magnet Roller (development), Transfer Roller
(transfer), and Detack Saw (peeling). The Engine Logic controls the printing
operation according to the information obtained through communications with the
Image Processor and from sensors and switches.
Image Processor Board This receives data from the Host Computer, performs
printing, and controls the whole printer.
Exit Motor PWBA This controls the Exit Motor Assembly according to a signal
from the HVPS/Engine Logic Board.
Interlock Switch Assembly This assembly consists of the following two safety
switches. See “Schematic Diagram of Power Distribution and Interlocks” on
page 2-33.
Top Cover Switch
This safety interlock interrupts the INTERLOCK BEF signal
between the LVPS and the HVPS/Engine Logic Board to indicate that the Top
Cover is open.
Laser Interlock This safety switch interrupts 5 VDC from the LVPS to the LD
Assembly of the Laser Assembly when the Top Cover is open. This switch
operates in series with the 5 V Interlock.