Xerox Phaser 8400 Service Manual page 49

The DC power supply generates + 3.3 V, +/- 15 V, and +/- 50 V. These voltages
provide direct or regulated voltage values to various circuits in the printer. The power
control board regulates +/- 15 V to +/- 12 and other voltages. The main board also has
regulators providing + 5 V, + 2.5 V, and + 1.8 V. The power supply outputs + 3.3 V in
ENERGY STAR mode. Fuse F1 provides protection for the switching power supply
in the DC section.
Warning
D
r
u
m
AC Line
AC Neutral
Low
Switcher
Theory of Operation
Do not touch the power supply; AC line voltages are present. The
power switch does not disconnect power from the printer. The
power switch signals the supply and the printer logic to begin a
shutdown sequence.
F3
F2
P
I
r
n
e
k
h
t 4
H
8
H
9
Control
Interface
+3.3 V
H13
H12
H11
H10
H9
uProcessor
H8
+15 V
H4
-15 V
H3
+50 V H2
-50 V
H1
AC Line
S1
AC Neutral
I I I
n n n
k k k
3 2 1
H
1
3
H
1
2
H
1
1
Serial
Vcc
REG
Vss
Line
Gnd Ref
Neutral
r r
e e
js js
s s
r I
2 1
H
1
0
H
4
H
3
H
2
H
1
s8500-022
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