278 N9030B PXA Signal Analyzer Service Guide
CPU/Disk Drive Troubleshooting
A4 CPU Description
A4 CPU Description
If the CPU board is suspect in an instrument failure, a full description of the
instrument boot process is described in Chapter 2, “Boot Up and Initialization
Troubleshooting”.
Disk Drive
The A5 Disk Drive can easily be removed from the A4 CPU assembly without
removing instrument covers. The disk drive is attached to a tray that is
accessed on the rear panel by loosening one screw and pulling the drive out of
the CPU assembly. The disk drive mates with the CPU board via the A4A1 Disk
Drive Interface Board. If the A4 CPU assembly is replaced, the existing A5 Disk
Drive must be transferred to the replacement CPU assembly.
A4A1 Disk Drive Interface Board
The disk drive interface board plugs into a header on the A4 CPU, attaches
with screws, and is separately replaceable. There may be situations where the
disk drive must be removed and inserted many times such as in a security
sensitive environment. Therefore, the low cost disk drive interface board can be
replaced if connector wear is an issue.
Front Panel Interface
The instrument USB bus is the electrical interface to the instrument front
panel. One of the USB ports on the host controller hub located on the A4 CPU
board assembly is routed to the A1A2 Front Panel Interface board for this use.
The port is a High Speed USB (2.0) compliant port.
Graphics Controller
The entire graphics subsystem is contained within a single chip, along with the
interface logic to map memory from main system memory for the video RAM.
There are two outputs of the graphics controller that are used by the
instrument. One provides the LCD video data to drive the internal instrument
LCD display and the other supplies the rear panel VGA output.
Power Supply Control
The power control line from the front panel momentary power switch connects
to the A4 CPU board assembly. When the front panel power switch is turned on
the A4 CPU board assembly pulls the PS_ON line to the A6 Power Supply
assembly to a TTL low level, which tells the power supply to turn on. Once the
+12V D, +5.1V D, and +3.35V D supplies are all on and within specification the
A6 Power Supply assembly pulls the PWROK_H line to a TTL high state, which
then causes the A4 CPU board to come out of reset and boot-up.
Outputs from the A4 CPU board assembly also drive the two front panel power
state LEDs.
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