A3 - Digital I/O Board Assembly; System Synchronization - Agilent Technologies N9039A Service Manual

A3 - Digital I/O Board Assembly

The A3 Digital I/O board assembly is serviced as an assembly only; no component
level repair is supported. For details on the functionality of this assembly see
Chapter 3, "Assembly Descriptions".
The A3 Digital I/O board assembly performs two important functions:

1. System synchronization

2. RF Preselector Filter hardware control

System Synchronization

There are two synchronization pulses generated on this assembly that are required
for the PSA EMI Measurement Receiver system to trigger properly when the
N9039A RF Preselector is being used in the Filter mode. These are rear panel
connections labeled:
External Trigger Out
Triggers a new sweep of the PSA
Pulse Trigger 2 Out
Gates the sweep of the PSA by providing a trigger pulse when the filter being
used is properly tuned to the frequency required.
There is no way to control these signals for troubleshooting purposes, nor are they
active, with the instrument by itself. The only way to measure these signals is to
have the instrument under control of a PSA in EMC Analyzer mode with the
Preselector Path being set to Filter. See the PSA EMI Measurement Receiver
Guide (Option 239) for details on how this is done.
With the N9039A RF Preselector configured properly in a PSA EMI Measurement
Receiver the two trigger outputs can be seen. To do this place a BNC tee in both
trigger lines, one end of each going to the correct PSA trigger input and the other
going to an oscilloscope input. If the system is configured with the following
settings you should see signals on the oscilloscope similar to those seen in
2-7, where channel 1 is the External Trigger Out and channel 2 is Pulse Trigger 2
Out.
Use Presel = Yes
Presel Path = Filter
Center Frequency = 100 MHz
Frequency Span = 2 MHz
Chapter 2
Troubleshooting

A3 - Digital I/O Board Assembly

Figure
51