Keysight N9038A Service Guide

370 Keysight N9038A MXE Service Guide
Power Supply & Midplane
A6 Power Supply Description
Control/Status Outputs
There are a number of control and status outputs for the A6 Power Supply
assembly. The ones that you will want to be familiar with are:
POWER_OK
is used to verify that the +12VD, +5.1VD, and +3.35VD are all on and within
specification. A TTL high level on this output brings the CPU out of reset and
initiates the instrument boot up process.
LINE_TRIGGER
is a TTL level signal that is synchronous to the AC line input. This signal is
typically used in spectrum analyzers to trigger an instrument sweep
synchronous to the AC power line.
FAULT_L
will be a TTL low level signal to indicate that the supply is experiencing an over
voltage, over current, or over temperature condition.
Fuse
The A6 Power Supply has no user replaceable fuse. While there is a fuse
internal to the supply this is not meant for field replacement. If the internal fuse
is blown, the power supply has experienced a major failure and should be
replaced.
Standby Supplies
The A6 Power Supply assembly has two standby supplies that should always
be on if the AC input voltage requirements are met. These are the +15VSB and
the +5.1VSB supplies. These supplies are used by the instrument to keep
certain circuits alive even when the power is turned off.
Over Current Protection
The A6 Power Supply assembly has built in over current protection that will
shut down the supply if current draw from the instrument is too great. The
power supply will remain on in over current state for a minimum of 1 second.
The power supply shall turn off no later than 5 seconds after the beginning of
the over current state. The power supply shall remain off until the line voltage
is removed and then reconnected or the front panel power switch is cycled.
Over current shut down does not apply to the standby supplies, the fan
voltage, and the +32VA supply.
Thermal Protection
The A6 Power Supply assembly will protect itself by shutting down if it
overheats. It will also reset itself with no user interaction after the temperature
is reduced by approximately 10 degrees C.

Keysight N9038A Specifications

General

Brand	Keysight
Model	N9038A
Category	Measuring Instruments
Language	English