Keysight N9038A, Руководство по обслуживанию

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326 Keysight N9038A MXE Service Guide
Analog & Digital IF
A2 Analog I.F. Troubleshooting
A2 Analog I.F. Troubleshooting
Assembly Initialization
Before the A2 Analog IF assembly will function properly it needs to initialize
itself when the instrument is turned on and be recognized by the instrument
software. The first step in verifying that this has happened is to look at the
instrument Hardware Information screen. To view this information press
System , Show , Hardware . Once you do this you will see a listing of instrument
hardware assemblies that are installed. The A2 Analog IF assembly should
identify itself on this list as Analog IF . If this assembly does not identify itself
the cause for this will need to be determined before any other troubleshooting
is performed. The most probable causes for this type of a problem would be:
— FPGA Code on the assembly is corrupt
Solution: Reload the FPGA code. See FPGA Synchronization in
Chapter 19, “Post-Repair Procedures” .
— An instrument power supply voltage is not operating properly
Solution: Verify all instrument power supply voltages. See Chapter
12, “Power Supply & Midplane” .
— A2 Analog IF assembly is defective
Solution: Replace the A2 Analog IF assembly
Signal Path Verification
While this assembly does create the 22.5 MHz IF signal, it does so with two
inputs that come from other assemblies. These two input signals are:
— 322.5 MHz IF Input from the A13 RF Front End Assembly
— 300 MHz 3rd LO Signal from the A16 Reference Assembly
Before looking for a fault on the A2 Analog IF assembly be sure to verify that
both of these signals are of the correct frequency and amplitude. Refer to
Chapter 6, “RF Downconverter Section” and Chapter 9, “Reference Assembly”
for detailed information on how to verify the frequency and amplitude of these
signals.
As can be seen in the block diagram for the A2 Analog IF assembly (see
Chapter 15, “Block Diagrams” ) there are many different signal paths through
this assembly, each of which includes a bandpass filter with a different
bandwidth. There is also a step gain amplifier that can be used with any of
these filter paths.
Refer to Chapter 15, “Block Diagrams” .