Agilent Technologies N5242A Service Manual page 85

PNA Series Microwave Network Analyzers
N5242A
If the Fans Are Not Operating
The power supply may be in thermal shutdown if the instrument has been
CAUTION
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
individual supplies. If the supplies are within specifications, the most probable cause is a
defective A14 system motherboard. Refer to
Motherboard" on page
If only one or two fans are not functioning, and the power supplies are within
specifications, suspect the A14 system motherboard or defective fan(s). Perform the
following procedure.
1. Remove the fan bracket, with fans attached, from the analyzer to expose the fan power
cable connections on the A14 system motherboard. Refer to
these connections. Refer to
2. Plug in the power cord and measure the fan voltages at all three connectors on the A14
system motherboard. THIS MUST BE DONE QUICKLY AS THE ANALYZER WILL
RAPIDLY OVERHEAT WITHOUT THE COOLING EFFECT OF THE FANS. DO NOT
PLUG IN THE POWER CORD UNTIL READY TO PERFORM MEASUREMENTS.
Figure 4-3 Fan Power Cable Connections
Service Guide N5242-90001
"Power Supply Check" on page 4-7
7-16.
"Removing and Replacing the Fans" on page
"Removing and Replacing the A14 System
Figure 4-3
Troubleshooting
Power Up Troubleshooting
to check the
for location of
7-60.
4-11