Self-Test; Failure Indications - HP 340 Series Service Manual

Self-Test
Use the self-test to troubleshoot a unit which can execute some instructions, but cannot accept,
store or output data correctly. This means that the basic elements of the SPU are functioning.
The basic elements include the power supply, processor board, and at least the first 16 Kbytes
of RAM. If any of these are not known to be functional, refer to the Initial Troubleshooting
Procedure section.
The self-test checks most assemblies in the SPU. Both pass and error displays in binary are
shown by the LED display. LED's are located behind the rear panel and are visible through
the vertical slot in the rear panel.
For a functional description of the self-tests, refer to Chapter 4.
Failure Indications
As the self-test progresses, the LED's display the current state. At the end of the test, a power-
up with no errors is indicated by all LEDs turned off and by immediate entry into the boot
scanner.
Should a failure occur during the self-tests, it will be indicated on the LEDs at the end of the
tests. If there was more than one failure, the highest priority failure will be indicated on the
LEDs. All the LED values are shown in Table 5-6.
The highest priority failure is also output to the beeper, if present. The lower seven bits of the
LED value are beeped in seven tones as follows:,
• Most significant bit first.
• One second beep per bit.
• A zero (LED off) is represented by a low tone.
• A one (LED on) is represented by a high tone.
If no failure occurs, the beeper will not sound off. If the failure was a Boot ROM checksum
error, the following rnessage will be displayed:
CONTINUE AT OWN RISK (Press RETURN To Continue)
Once this lllessage has been printed, the
I
Return
I
key must be pressed to continue to the boot
scanner. The probability is fairly low that the error will adversely affect the user, but if it does,
it could be catastrophic.
For all other failures, the message:
WAITING 1 MINUTE (Press RETURN To Abort Wait)
will be displayed.
Troubleshooting
89