Power Supply Theory Of Operation - Keysight N8973B Service Manual

Power Supply/Midplane Troubleshooting
A6 Power Supply Description

Power Supply Theory of Operation

The A6 Power Supply assembly is serviced as an assembly only; no component
level repair is supported.
The A6 Power Supply assembly provides most all of the necessary DC voltages
for the signal analyzer. If any of the power supplies are not within their
operating voltages, the instrument will not function properly.
The A6 Power Supply assembly is a switching supply that operates at a
frequency of ~120 kHz.
The A6 Power Supply assembly is an auto ranging supply, requiring no user
selection of the input voltage. The input AC voltage and frequency
requirements for the A6 Power Supply assembly are printed on the rear panel
of the instruments as well as on the power supply itself.
While there are no test points or status LEDs accessible for troubleshooting on
the A6 Power Supply assembly, there are both test points and status LEDs for
all of the different power supply voltages, as well as other power supply status
lines, on the A7 Midplane Board assembly. See the
on page 312
Supply Voltages
The following voltage levels are produced by the A6 Power Supply assembly:
Vol tage Ground
Level Reference
+15V SB ACOM
+5.1V SB DCOM
+32V A ACOM
+15V A ACOM
+9V A ACOM
+5.2V A ACOM
Keysight NFA Series Noise Figure Analyzers Service Guide
for detailed information on the location of each
A7 Midplane Vol tage
Connector Level
J101 +12V D
J111/J112 +5.1V D
J101 +3.35V D
J103/J104 -15V A
J104 -7V A
J102 FAN POS
FAN NEG
"A7 Midplane Description"
Ground A7 Midplane
Reference Connector
DCOM J111
DCOM J109/J110
DCOM J107/J108
ACOM J105
ACOM J105
FAN NEG J101
FAN POS J101
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