Power Supply Regulators - HP 9000 Series 310 Service Information Manual

Switching Control Circuit
Voltage from the rectifier feeds a Switching Control Circuit that controls the amount of power
going to each of the output voltage regulators. +5 V dc feedback is applied to the Switching
Control Circuit to regulate the +5 V dc output. Overvoltage protection signals also input the
Switching Control Circuit that will cause the power supply to shut down if voltage in the output
supplies goes too high. A +5 V dc over-current sensor input is another input to the Switching
Control Circuit.
Power Transformer
Input ac voltage is also applied to the primary windings of a power transformer. Three sets
of secondary windings each feed a voltage regulator for the output voltages. A voltage select
switch is set to the line voltage range and causes the power transformer to have the same voltage
output for both line voltage ranges.
Power Supply Regulators
Functions of the Power Supply Regulators are:
• +5 V dc Power Supply
• +
12 V dc Power Supply
• -12 V dc Power Supply
+5 V de
Voltage fronl the power transformer feeds through a +5 V dc current sensor than goes to the
+5 V dc rectifier. Output frOln the +5 V dc rectifier is nominally 5.07 V dc ±0.18 V dc. The
+5 V dc output is also fed to the +5 V dc Feedback Loop Circuit for regulation. It also is fed to
the Overvoltage Protection Circuit and Reset Circuit. If the +5 V dc fails, the Power-On LED
on the front panel will go out as the +5 V dc is part of the controlling voltage for the Switching
Control Circuit.
+12 V de
Voltage frolll the power transformer feeds through a rectifier then to a
+
12 V dc Post Regulator.
The output from the Post Regulator is nominally + 12.29 V'dc ±0.43 V dc. In addition to being
distributed in the computer (or bus expander), the +12 V dc output is also fed to the Overvoltage
Protection Circuit and Reset Circuit. External to the power supply, the
+
12 V dc is connected
to one side of the Power-On LED on the front panel.
-12 V de
Voltage frOIn the power transformer feeds directly to a -12 V dc Post Regulator. The output
from the Post Regulator is nOIninally -12.29 V dc ±0.43 V dc. In addition to being distributed
in the computer (or bus expander), the +12 V dc output is also fed to the Overvoltage Protection
Circuit and Reset Circuit. External to the power supply, the -12 V dc is connected to the other
side of the Power-On LED on the front panel.
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Functional Description