Keysight N9038A, Руководство по обслуживанию, Страница: 45 / 745

Keysight N9038A MXE Service Guide 45
Boot Up and Initialization
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 and is
then buffered on the A8 Motherboard before being sent to the A1A2 Front
Panel Interface board through W8. 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 18, “Assembly Replacement Procedures”, on page 527 in this
manual.
3. Remove the Top Brace. Refer to Chapter 18, “Assembly Replacement
Procedures”, on page 527 in this manual.
4. With AC power connected to the rear of the instrument but without
turning it on, leaving it in standby mode, measure the voltage at Test Point
518 (POWER_ON_L) of the A7 Midplane board assembly. See Figure 2-4
for Test Point 518 location.
Does the voltage at Test Point 518 measure 5 VDC?
If yes:
Proceed to step 5 .
If not:
Replace the A6 Power Supply assembly.
Before replacing the power supply, verify the midplane and motherboard interconnects are
mechanically secure.