A6 Power Supply Basic Troubleshooting; (Cover On) - Keysight N8973B Service Manual

Power Supply/Midplane Troubleshooting
A6 Power Supply Basic Troubleshooting (Cover On)

A6 Power Supply Basic Troubleshooting

(Cover On)

There are no user replaceable fuses on the power supply. If the internal
fuse is blown, the power supply has experienced a major failure and should
be replaced. If you determine that the power supply is the failed assembly,
replace the power supply. If the power supply is suspect, perform the
following quick checks before removing the instrument cover.
1. Ensure the instrument is plugged into a known good AC power source and
2. Power on the instrument and verify that the green LED on the front panel
3. Verify both fans are operating on the side panel of the instrument. The fans
4. The front panel probe power connector can be used to check the +15 VDC
Exercise great care when measuring voltages on the Probe Power
connector. Accidentally shorting the +15V or -12.6V supply to ground can
cause damage to the A1A2 or A1A5 assemblies.
Figure 10-2 Probe Power Connector
If these initial checks are functioning properly and yet the signal analyzer will
not boot up properly, or the display is not turning on, refer to
Up and Initialization Troubleshooting"
310
the yellow standby LED near the power on switch is illuminated. A lit
yellow LED indicates the +5.1 SB VDC power supply voltage is providing
enough voltage to light the LED.
is lit. A lit LED indicates the power supply has received an "ON" command
from the A4, CPU assembly and that the +5.2A VDC supply is on.
can be heard once the analyzer is powered up. If the fans are operating,
the fan power supply is functioning.
(+/- 7%) and -12.6 VDC (+/-10%) supplies. The -12.6 VDC is produced by
post regulating the -15 VDC supply. A voltmeter can be used to verify
these supplies. Refer to
connector.
Figure 10-2 for a diagram of the probe power
in this service manual.
Keysight NFA Series Noise Figure Analyzers Service Guide
Chapter 2, "Boot