Fan(S) Are Not Operating - Keysight N8973B Service Manual

Boot Up and Initialization Troubleshooting
Potential Problems During Boot Process

Fan(s) Are Not Operating

Control of the instrument fans comes from the A6 Power Supply assembly. This
signal is routed from the A6 Power Supply through the A7 Midplane board,
where there is a test point and LED to monitor the level, and is then routed to
the A8 Motherboard where it is filtered before being sent to the Fans. When the
Fans do 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 green Power On LED on the front panel does
turn on when the instrument is turned on. If it doesn't, refer to the
Power On LED Does Not Illuminate"
1. The instrument fans will only turn on when the instrument is connected to
2. Remove the AC power cord and then remove the instrument cover. Refer
3. Are both fans not spinning?
If yes:
If no:
4. Remove the MP7 Top Brace. Refer to
5. Refer to
If yes:
56
an AC 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.
to the Chapter 15, "Assembly Replacement Procedures", on page 389
this manual.
Proceed to step
Proceed to step
Procedures", on page 389
Figure 2-5, verify that the Fan LED on the A7 Midplane board is
on. Is the Fan LED on?
Measure the voltage level at TP1 on the A7 Midplane board. Is the
TP1 voltage between +7 and +15 VDC
If yes:
If no:
section before proceeding.
4.
6.
Chapter 15, "Assembly Replacement
in this manual.
Proceed to step 6.
Replace the A6 Power Supply assembly.
Keysight NFA Series Noise Figure Analyzers Service Guide
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