Live Unit Procedure; Minimum Configuration - HP 340 Series Service Manual

Live Unit Procedure
A live unit is one which has a properly functioning power supply but the SPU will not function.
One of the assemblies installed (other than the power supply) is usually defective. Live units
often are very difficult to troubleshoot, since a problem anywhere on the I/O bus in the SPU
can shut the workstation down and prevent the execution of any instructions, even those from
the Boot ROM.
The Live Unit Procedure is a nlethod for finding the defective asselnbly which is preventing the
processor from executing instructions. It assumes that the power supply is operating properly,
and the self-test tried to run, but didn't.
If the power supply is not operating properly, refer to the Dead Unit Procedure. If the turn-on
self-test runs enough to either display a failure, stalls in a meaningless state, or passes, refer to
the Functional Unit Procedure.
Once the problem in the workstation has been isolated to the SPU, it
1S
sometimes best to start
with a minimum configuration.
Minimum Configuration
A mininlum SPU configuration consists of:
• Power Supply.
• Processor Board.
• One RAM Board.
These are needed to start self-tests. All self-tests don't have to complete or pass, just start.
You may have to remove the video/graphics or interface boards for the SPU to function if a
problem is on one of these boards.
Testing the minirnum configuration is relatively simple. Just remove the internal assenlbly,
RAM, video, SPU backplane and interface boards, then follow these steps:
l. Plug the SPU in and turn it on. The Self-Test LED's should ripple and change state
several times.
2. If the LED's do not light or ripple, turn the SPU off, unplug it, and replace the processor
board, then retest.
:1. Turn it on, and watch the LEDs. If the LED's don't light or ripple, replace the power
supply.
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Trou bleshooting