54 Keysight Technologies N9040B UXA Signal Analyzer Service Guide
Boot Up and Initialization Troubleshooting
Potential Problems During Boot Process
Green Power On LED Does Not Illuminate
Control of the green front panel Power On LED comes from the A4 Processor
board assembly. This signal is routed through the A7 Midplane board before
being sent to the A1A2 Front Panel Interface board through W1. Of course, the
power for this all originates with the A6 Power Supply Assembly. When the
Power On LED does not come on it could be due to any one of these
assemblies. This procedure will help to determine which one is the cause.
This procedure assumes that the yellow Standby LED does turn on when the
AC power is connected to the rear panel of the instrument. If it doesn't, refer to
the “Yellow Standby LED Does Not Illuminate” section before proceeding.
If the instrument turns on and operates properly but the green Power On LED
does not work then all that will need to be done is to trace where the control
signal for the LED is being lost using the routing information in the preceding
paragraph.
1. The Power On LED will only turn on when the instrument is connected to
an AC power source that has a voltage level and frequency of that
specified for the instrument and the front panel On/Off button has been
pressed. Before proceeding verify that these requirements are being met.
Refer to the instrument rear panel for these requirements.
2. Remove the AC power cord and then remove the instrument cover. Refer
to Chapter 15, “Assembly Replacement Procedures”, on page 347 in this
manual.
3. Remove the Top Brace. Refer to Chapter 15, “Assembly Replacement
Procedures”, on page 347 in this manual.
4. Power on the UXA while visually monitoring the green LED’s by referring to
the two figures below.
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