HP mt245 mt245 Mobile Thin Client Maintenance and Service Guide - Page 74

Power-On Sequence, Power-On Diagnostic Tests, Troubleshooting

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Power-On Sequence At power-on, the flash boot block code initializes the hardware to a known state, then performs basic poweron diagnostic tests to determine the integrity of the hardware. Initialization performs the following functions: 1. Initializes CPU and memory controller. 2. Initializes and configures all PCI devices. 3. Initializes VGA software. 4. Initializes the video to a known state. 5. Initializes USB devices to a known state. 6. Performs power-on diagnostics. For more information, see "Power-On Diagnostic Tests". 7. The unit boots the operating system. Power-On Diagnostic Tests The Power-on diagnostics performs basic integrity tests of the hardware to determine its functionality and configuration. If a diagnostic test fails during hardware initialization the unit simply stops. There are no messages sent to video. NOTE: You may try to restart the unit and run through the diagnostic tests a second time to confirm the first shutdown. The following table lists the tests that are performed on the unit. Test Boot Block Checksum DRAM Serial Port Timer RTC CMOS battery NAND flash device Description Tests boot block code for proper checksum value Simple write/read pattern test of the first 640k of memory Tests the serial port using simple port verification test to determine if ports are present Tests timer interrupt by using polling method Tests integrity of RTC CMOS battery Tests for proper NAND flash device ID present Troubleshooting Basic Troubleshooting If the computer is experiencing operating problems or will not power on, review the following items. Table 8-1 Power-On Troubleshooting Issue Procedures The computer unit is experiencing operating problems. Ensure that the following connectors are securely plugged into the computer: Power connector, keyboard, mouse, network RJ-45 connector, monitor 66 Chapter 8 Diagnostics and Troubleshooting

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Power-On Sequence
At power-on, the
flash
boot block code initializes the hardware to a known state, then performs basic power-
on diagnostic tests to determine the integrity of the hardware. Initialization performs the following functions:
1.
Initializes CPU and memory controller.
2.
Initializes and
configures
all PCI devices.
3.
Initializes VGA software.
4.
Initializes the video to a known state.
5.
Initializes USB devices to a known state.
6.
Performs power-on diagnostics. For more information, see “Power-On Diagnostic Tests”.
7.
The unit boots the operating system.
Power-On Diagnostic Tests
The Power-on diagnostics performs basic integrity tests of the hardware to determine its functionality and
configuration.
If a diagnostic test fails during hardware initialization the unit simply stops. There are no
messages sent to video.
NOTE:
You may try to restart the unit and run through the diagnostic tests a second time to
confirm
the
first
shutdown.
The following table lists the tests that are performed on the unit.
Test
Description
Boot Block Checksum
Tests boot block code for proper checksum value
DRAM
Simple write/read pattern test of the
first
640k of memory
Serial Port
Tests the serial port using simple port
verification
test to determine if ports are present
Timer
Tests timer interrupt by using polling method
RTC CMOS battery
Tests integrity of RTC CMOS battery
NAND
flash
device
Tests for proper NAND
flash
device ID present
Troubleshooting
Basic Troubleshooting
If the computer is experiencing operating problems or will not power on, review the following items.
Table 8-1
Power-On Troubleshooting
Issue
Procedures
The computer unit is experiencing operating
problems.
Ensure that the following connectors are securely plugged into the computer:
Power connector, keyboard, mouse, network RJ-45 connector, monitor
66
Chapter 8
Diagnostics and Troubleshooting