4-12 Service Guide N5227-90001
Troubleshooting PNA Series Microwave Network Analyzers
Power Up Troubleshooting N5227A
If the correct voltage is not present, suspect a defective A18 system motherboard. Refer to “Removing
and Replacing the A18 System Motherboard” on page 7-11.
Troubleshooting LCD Display Problems
This procedure is intended to isolate the faulty assembly when the display is dark. If the display is lit, but the
color mix is faulty, refer to “A3 Display Test” on page 4-15.
NOTE There are no front panel adjustments for intensity and contrast of the LCD.
1. If the display is dim, the A3 display assembly is defective. Refer to “Removing and Replacing the A1–A3
and Other Front Panel Subassemblies” on page 7-8.
If the display is dark (not visible), connect an external VGA monitor to the rear panel Monitor output
connector. (Be aware that some multisync monitors might not be able to lock to a 60 Hz sync pulse.) If
the video information is not present on the external VGA monitor, the most probable cause is the A21
CPU board. Refer to “Removing and Replacing the A21 CPU Board Assembly” on page 7-18.
2. If the external VGA monitor displays the correct information, verify that the front panel interface ribbon
cable is properly plugged into the motherboard connector. Refer to “Removing and Replacing the Front
Panel Assembly” on page 7-7.
3. If the front panel interface ribbon cable is properly connected, suspect that one or more of the following
is defective:
• inverter board (mounted on the display assembly)
• A1 front panel interface board
• A3 display assembly
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