4-12 Service Guide N5230-90014
Troubleshooting PNA Series Microwave Network Analyzers
Power Up Troubleshooting N5230A
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 “A2 Display Test” on page 4-18.
NOTE
There are no front panel adjustments for intensity and contrast of the LCD.
1. If the display is dim, the backlight assembly is defective. Refer to “Removing and
Replacing the Front Panel Assembly” on page 7-8.
If the display is dark (not visible), connect an external VGA monitor to the rear panel VGA
output connector on the instrument. 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 A15 CPU board. Refer to “Removing and
Replacing the A15 CPU Board” on page 7-20.
2. If the external VGA monitor is functioning, verify that the front panel interface ribbon
cable is properly plugged into the motherboard connector.
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)
• display lamp assembly
• A3 front panel interface board
• A2 display assembly
Refer to the following paragraphs to determine which of the above listed assemblies is
defective.
Creating the Test Setup
For easy access to measure the voltages on the inverter board and on the A3 front panel
interface board, it is best to disassemble the front panel and remove these two boards to
set in front of you for testing. Use the ribbon cables that come with the boards and the
analyzer as the supply source. Follow this procedure:
1. Turn off the analyzer.
2. Remove the front panel. Refer to “Removing and Replacing the Front Panel Assembly”
on page 7-8.
3. After the front panel is removed from the analyzer, isolate the inverter board by first
removing the display assembly. Refer to “Removing the A2 Display Assembly” on
page 7-10. Put the A2 display assembly and its ribbon cables aside.
4. Remove the A3 board by referring to “Removing the A3 Front Panel Interface Board” on
page 7-10. Put the A3 board aside.
5. Duplicate the board connections on your ESD safe test desk top by laying the A2 and A3
in front of the open-faced analyzer. Lay the A2 and A3 boards component-side down, the
A2 to the left of the A3, with the top of the boards towards you.
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