Keysight Technologies N9030B Service Manual page 306

Power Supply/Midplane Troubleshooting
A6 Power Supply Assembly Troubleshooting
306
temperature condition. However, there is no way to know at the A6
Power Supply assembly level which one of these conditions may be
the cause of a TTL low level to be on the FAULT_L status output.
While any over voltage or over temperature conditions will most
likely be caused by an A6 Power Supply assembly failure, an over
current condition will most likely be caused by another assembly in
the instrument demanding too much current.
If this output is not at a TTL high level the A6 Power Supply assembly
will not turn its non-standby power supplies on, no matter what the
A4 Processor assembly tells it to do.
If the A6 Power Supply assembly is suspected of causing the
instrument to not power on properly the status of this output line can
be verified by either measuring the voltage level at Test Point 508 on
the A7 Midplane board assembly or by viewing the status of the
FAULT_L LED. See the A7 Midplane Board AssemblyTroubleshooting
section in this chapter for detailed information on the location of this
test point and LED as well as the expected status for both when the
instrument is operating properly.
N9030B PXA Signal Analyzer Service Guide