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HP 9020 User Manual

HP 9020
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2-4
Theory
of
Operation
Power Supply Assembly
WARNING
DO NOT SERVICE THE POWER SUPPLY ASSEMBLY UNTIL THE
COMPUTER POWER CORD HAS BEEN UNPLUGGED FROM THE
AC
OUTLET AND THE POWER SUPPLY CAPACITORS HAVE
BEEN
COMPLETELY DISCHARGED.
SEE
CHAPTER 4
FOR
ADDI-
TIONAL INFORMATION.
The power supply assembly
is
a switching regulator assembly that provides power to the entire
computer. Figure 2-3
is
a functional block diagram of the assembly. The power supply assembly
converts ac line voltage to the following dc voltages. The actual voltages are listed
first~
the voltages
in
parentheses are the truncated designations used throughout the manual.
+ 17.5 to +
23
( + 19 unregulated)
-17.5
to -
23
(-19
unregulated)
+
16
(+
16
bias supply voltage)
+ 12.1
(+
12)
+ 12.1
(+
12MM, Mass Memory)
-12.1
(-12)
+6.7
(+6)
+5.1
(+5)
+3.85
(+3)
-2
(-2)
LEOs
on
the assembly indicate overvoltage or undervoltage conditions for dc supplies, as well as
overtemperature, peak power exceeded,
and
110
door or processor stack door open.
An
ac module which mounts above the
110
card cage
is
connected to the assembly by a cable
harness. The ac module consists of an on/off power switch/circuit breaker, line
filter,
and
wiring
harness.
An
attached male line cord plugs into the ac power source.
The power supply assembly
is
cooled by a dc box fan mounted
on
the rear of the mainframe. The
fan
is
not
an
integral part of the assembly.
The power supply assembly has three printed circuit boards: the primary board, the secondary
board,
and
the supervisor board. The following description
is
organized according to the functions
performed by the ac module
and
these three boards.
The power supply assembly plugs into the motherboard
in
the computer base via six connectors,
two per board. These connectors,
and
their associated motherboard traces, interconnect the power
supply assembly boards,
and
carry voltage and signal lines between the power supply assembly
and
other computer modules.
Fifteen status-indicating, light-emitting diodes (LEOs) are contained on the supervisor board. They
are described
in
a following subsection
in
this chapter.

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HP 9020 Specifications

General IconGeneral
BrandHP
Model9020
CategoryDesktop
LanguageEnglish

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