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Assembly Descriptions
A6 Power Supply Description
Control Inputs
There are a number of control inputs for the A6 Power Supply assembly. They are:
• POWER_ON is a signal that when pulled low tells the A6 Power Supply
assembly to turn on all of its outputs. This signal comes from the A4 Processor
board assembly and is initiated by pressing the front panel power button.
• DITHER is an AC coupled analog signal going to the supply that is used to
frequency modulate the power supply switching frequency for the purpose of
lowering any power supply related interference.
• OFFn is an input that is to be used only as a "Panic Stop". This signal can be
used for such functions as an emergency over temperature shut down. This type
of shut down is a last resort and does not perform the recommended operating
system shut down of the instrument.
Control/Status Outputs
There are a number of control and status outputs for the A6 Power Supply
assembly. They are:
• POWER_OK is used to verify that the +12V D, +5.1V D, and +3.35V D 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.
• LSYNC is a TTL level signal that is synchronous to the AC line input. While it
is unused in this application, this type of a signal is typically used to trigger an
instrument sweep synchronous to the AC power line.
• PS_TEMP is a read out of the internal temperature of the power supply.
• PS_FAULT 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.
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Chapter 3
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Table of Contents
Troubleshooting
