Agilent Technologies N5230A, Service Manual, Page: 81 / 262

Service Guide N5230-90014 4-11
PNA Series Microwave Network Analyzers Troubleshooting
N5230A Power Up Troubleshooting
If the Fans Are Not Operating
CAUTION The power supply may be in thermal shutdown if the instrument has been
operating without the fans running. Allow the instrument to cool down before
troubleshooting.
If all three fans are not operating, suspect a power supply problem or a defective A14
system motherboard. Refer to
“Power Supply Check” on page 4-7 to check the individual
supplies. If the supplies are within specifications, the most probable cause is a defective
A14 system motherboard. Refer to
“Removing and Replacing the A14 System
Motherboard” on page 7-18 .
If only one or two fans are not functioning, and the power supplies are within
specifications, suspect the A14 system motherboard or a defective fan. Perform the
following procedure.
1. Remove the front panel assembly from the instrument. Refer to “Removing and
Replacing the Front Panel Assembly” on page 7-8 .
2. Refer to Figure 4-4 . Measure the fan voltages at J1, J3, and J4 on the A14 system
motherboard.
Figure 4-4 Fan Voltages
3. If the correct voltage is present and the fan connector is in good mechanical condition,
suspect a defective fan. Refer to “Removing and Replacing the Midweb and the B1
Fan” on page 7-40 .
If the voltage is not present, suspect a defective A14 system motherboard. Refer to
“Removing and Replacing the A14 System Motherboard” on page 7-18 .