4-10 Service Guide N5227-90001
Troubleshooting PNA Series Microwave Network Analyzers
Power Up Troubleshooting N5227A
page 7-10).
7. Remove the A17 13.5 GHz synthesizer board (refer to “Removing and Replacing the A4–A17 Boards” on
page 7-10).
8. Remove the A4 13.5 GHz synthesizer board, if present (refer to “Removing and Replacing the A4–A17
Boards” on page 7-10)
9. Remove the A14 frequency reference board (refer to “Removing and Replacing the A4–A17 Boards” on
page 7-10).
10. Remove the A22 GPIB board (refer to “Removing and Replacing the A22 GPIB Board” on page 7-20).
Reinstall the A20 power supply assembly and the A21 CPU board assembly.
11. Unplug the A55 hard disk drive from the A21 CPU board (refer to “Removing and Replacing the A55 Solid
State Drive (SSD)” on page 7-42).
The minimum required assemblies to power up the analyzer are:
• A20 power supply
• A19 midplane board
• A18 system motherboard
•A21 CPU board
To further isolate the failure in the three remaining assemblies, measure the resistance (with the power
turned off) from the power supply test points to either ACOM or DCOM.
NOTE Make sure that the only assemblies plugged in are the four minimum required assemblies
listed above.
NOTE Check for shorts (zero ) or very low resistance (approximately 1 ). If a short or low
resistance is measured, isolate each of the remaining four boards in the following order, and
recheck the shorted test point after each board is removed. You should be able to determine
if the shorted condition has changed.
NOTE Isolate the remaining three assemblies:
• remove the A21 CPU board
• remove the A20 power supply
• remove the A19 midplane board
• This leaves only the A18 system motherboard installed. If the resistance measurements are still
incorrect, this is the suspected faulty assembly.
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