Power Supply Check - Keysight N5224A Service Manual

PNA Series Microwave Network Analyzers
N5224A and N5225A

Power Supply Check

NOTE There are no fuses to replace within the power supply. If you determine that the power
supply is the failed assembly, replace the power supply.
A catastrophic failure in the power supply can be determined by observing the line switch and the power
supply LED indicators:
1. Ensure that the instrument is plugged in with the power switch in the standby position (power not
switched on). Verify that the line switch displays a yellow light - this indicates that the power supply
standby line is active and functional.
2. Turn on the instrument power and verify that the line switch displays a green light - this indication that
the power supply is active and does not sense an over-current condition.
3. You can determine which power supplies are functioning by viewing the LED indicators on the A19
midplane board. Refer to
To view the LED indicators, it is necessary to remove the instrument's outer and inner covers. Refer to
"Removing the Covers" on page 7-6
midplane board, refer to
CAUTION Do not operate the analyzer with the outer cover removed for more than 30 minutes, as this
could cause the analyzer to overheat which could result in costly damage.
4. If any power supply voltage is missing, it is likely that the problem is a defective A20 power supply, the
A19 midplane board, or another assembly that is loading down the A20 power supply. Continue with
Any Supply Voltage Is Missing" on page 4-9
5. If the line switch is lit correctly, and all the power supply voltages appear to be present, as indicated by
the LEDs as shown in
power supply could still be at fault. Continue at
the actual supply voltages are correct.
Measure the Individual Supply Voltages
Measure the power supply voltages using a digital multi-meter. Use the point labeled ACOM as ground
reference for analog supplies and the point marked DCOM as ground reference for digital supplies.
Refer to Figure 4-2 for the power supply measurement points on the A19 midplane board. Refer to
on page 4-9 for the correct voltages.
Service Guide N5225-90001
Figure 4-2.
for removal procedures. To determine the location of the A19
"Top Assemblies and Cables, All Options" on page
to determine the cause of the problem.
Figure 4-2, the power supply has not suffered a catastrophic failure. However, the
"Measure the Individual Supply Voltages"
Troubleshooting
Power Up Troubleshooting
6-16.
to verify that
Table 4-1
"If
4-7