4-10 Service Guide N5242-90001
Troubleshooting PNA Series Microwave Network Analyzers
Power Up Troubleshooting N5242A
5. Remove the A5 source board, if present (refer to “Removing and Replacing the A4–A13
Boards” on page 7-14).
6. Remove the A11 13.5 GHz synthesizer board (refer to “Removing and Replacing the
A4–A13 Boards” on page 7-14).
7. Remove the A13 13.5 GHz synthesizer board (refer to “Removing and Replacing the
A4–A13 Boards” on page 7-14).
8. Remove the A4 13.5 GHz synthesizer board, if present (refer to “Removing and
Replacing the A4–A13 Boards” on page 7-14)
9. Remove the A10 frequency reference board (refer to “Removing and Replacing the
A4–A13 Boards” on page 7-14).
10. Remove the A18 GPIB board (refer to “Removing and Replacing the A18 GPIB Board”
on page 7-24). Reinstall the A16 power supply assembly and the A17 CPU board
assembly.
11.Unplug the A51 hard disk drive from the A17 CPU board (refer to “Removing and
Replacing the A51 Hard Disk Drive (HDD)” on page 7-48).
The minimum required assemblies to power up the analyzer are:
• A16 power supply
• A15 midplane board
• A14 system motherboard
• A17 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.
Check for shorts (zero Ω) or very low resistance (approximately 1 Ω). 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.
Isolate the remaining three assemblies:
• remove the A17 CPU board
• remove the A16 power supply
• remove the A15 midplane board
• This leaves only the A14 system motherboard installed. If the resistance measurements
are still incorrect, this is the suspected faulty assembly.
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