Turn-On Self-Test - HP 200 Series Hardware Support Document

58
Troubleshooting and Diagnostics
Turn-on Self-test
The turn-on self-test is a troubleshooting tool which can be used to test a unit which can execute
some instructions, but still fails to operate properly. This means that the power supply, processor,
CPU bus, boot ROMs and at least the first 16K bytes of RAM are functioning. If any of these are not
known to be functional, refer to the initial troubleshooting procedure and flowchart.
The tum-on self-test checks many portions of the computer and produces error and status mes-
sages on the CRT. It also displays error codes on the self-test LED display located on the rear edge
of the processor board, and annunciates the seven least -significant digits of the error code on the
speaker.
Self-test LEDs Location
The LEOs are read from back to front. The speaker represents a 0 with a low-pitched beep and a 1
with a high-pitched beep.
Self-test starts by turning all of the self-test LEOs on, then qUickly turning them off from back to
front. It then starts the tests of individual sections. If this routine does not occur, not enough
hardware is operating for the self-test to be meaningful. Refer to the initial troubleshooting proce-
dure.