HP 330 Service Information Manual page 177

Self-Test
Use the self-test to troubleshoot a unit which can execute some instructions, but cannot ac-
cept, store or output data correctly. This means that the basic elements of the computer are
functioning. The basic elements include the power supply, processor board, and at least the
first 16k bytes 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 computer. Both pass and error displays in binary are
shown by the LED display. LED's are located behind the front panel and are visible through
the holes in the front 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 5-3.
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 message 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
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