So much of the systems operation is based on the system board that it can have several different types of symptoms. Typically symptoms associated with system board hardware failures include the following:
* The On/Off indicator lights are visible, the display is visible on the monitor screen, but there is no disk drive action and the machine does not boot up.
* The On/Off indicator lights are visible, the hard drive spins up, but the system appears dead and there is no boot up.
* The system locks up during normal operation.
* The system produces a beep code with 1,2,3,5,7 or 9 beeps.
* The system produces a beep code of 1 long and 3 short beeps.
* The system will not hold date and time.
* An 8042 Gate A20 Error message displays error getting into protected mode.
* An Invalid Switch Memory Failure Message displays.
* A DMA ERROR message displays DMA controller failed page register test.
* A CMOS Battery Low message display, indicating failure of CMOS battery or CMOS checksum test.
* A CMOS System Option Not Set message displays, indicating failure of CMOS battery or CMOS checksum test.
* A CMOS Checksum Failure message dsiplays, indicating CMOS battery low or CMOS checksum test failure.
* A 201 error code displays, indicating a RAM failure.
* A parity check error message displays, indicating a RAM error.
Typical symptoms associated with system board setup failures include the following:
* A CMOS inoperational message displays, indicating failure of CMOS shutdown register.
* A Display Switch Setting Not Proper message displays failure to verify display type.
* A CMOS Display Mismatch message displays failure of display type verification.
* A CMOS Memory Size Mismatch message displays system configuration and setup failure.
* A CMOS Time & Date Not Set message displays System configuration and setup failure.
* An IBM compatible error code displays, indicating that a configuration problem has occurred.
Typical symptoms associated with system board I/O failure include the following:
* Speaker doesn't work during operation. The rest of the system works, but no sounds are produced through the speaker.
* Keyboard does not function after being replaced with a known good unit.
Most of the hardware problems that occur with computers, outside of those already described, involve the system board. Because the system board is the center of virtually all the computers operations, it is only natural that you must check it at some paint in most troubleshooting efforts. The system board normally marks the end of any of the various troubleshooting schemes given for different system components. It occupies this position for two reasons. Firs the system board supports most of the other system components, either directly or indirectly. Second, it is the system component that requires the most effort to replace and test.