HP 8924E, Assembly

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Chapter 2, Troubleshooting
More about Step 4 - Verify Test Set Functioning
N:\mkt\MANUALS\HP8924C\ALR\trouble.fb
Swapping Known-Good Assemblies
Swapping a known-good assembly for a suspected faulty assembly performed
Most swapped assemblies which use calibration data will operate well enough
with the original assembly’s calibration data to troubleshoot and to run the
diagnostics; do not expect the Test Set to meet its specifications. Some assemblies
may appear to fail because of incorrect calibration data. It is also important to
keep track of the original assemblies in the Test Set. If calibration data is lost, the
assembly will have to be sent back to the factory.
Calibration data is generally stored in a socketed EEPROM on the A16 Host
Controller. If the controller is replaced or swapped, the original EEPROM must be
put in the new Test Set’s Controller. Should the EEPROM lose its data, the entire
instrument will require a factory recalibration.
The assemblies that require down-loaded calibration data from a memory card
are:
• A19 Receiver 1st Mixer
• A26 Output
• A24 Signal Generator Synthesizer
• A27 Reference
• A30 Receiver
• A28 Receiver Synthesizer
• A32 Spectrum Analyzer (optional in some Test Sets)
• A37 Measurement
• A33 HP-IB/RS-232/Current Sense
• A5 Input
• A4 Attenuator
Of these assemblies the A5 Input is the least likely candidate for a successful
assembly swap.
The A32 Spectrum Analyzer may also pose difficulties. To verify operation, first
set the Spectrum Analyzer’s
RF Gen
controls to
Track
, and the
Port/Sweep
field to
Dupl
. This directs the Tracking Generator to the DUPLEX OUT port.
Connect the DUPLEX port to the ANT IN port. Set the
Main
control to
Ant
. Set
the
Center Freq
to 501 MHz, and the
Span
to 1 GHz. You should see a
(roughly) flat line across the screen, varying about 4dB. “
Generator sweep
truncated
” may appear - but does not indicate a problem.