Lenovo ThinkCentre M79, Hardware Maintenance Manual

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Chapter 9. Service checkout and symptom-to-FRU index
This chapter provides information about general service checkout and symptom-to-FRU index.
Service checkout
Attention: The drives in the computer you are servicing might have been rearranged or the drive startup
sequence changed. Be extremely careful during write operations such as copying, saving, or formatting.
Data or programs can be overwritten if you select an incorrect drive.
General error messages appear if a problem or conflict is found by an application program, the operating
system, or both. For an explanation of these messages, refer to the information supplied with that software
package.
Before replacing any FRUs, ensure that the latest level of BIOS is installed on the system. A down-level BIOS
might cause false errors and unnecessary replacement of the system board. For more information on how to
determine and obtain the latest level BIOS, see “BIOS levels” on page 68.
Use the following procedure to help determine the cause of the problem:
1. Power-off the computer and all external devices.
2. Check all cables and power cords.
3. Set all display controls to the middle position.
4. Power-on all external devices.
5. Power-on the computer.
• Look for displayed error codes
• Listen for beep codes
• Look for readable instructions or a main menu on the display.
If you
did not receive the correct response, proceed to step 6 on page 91.
If you do receive the correct response, proceed to step 7 on page 91.
6. Look at the following conditions and follow the instructions:
• If you hear beep codes during POST, go to “Beep symptoms” on page 93.
• If the computer displays a POST error, go to “POST error codes” on page 93.
• If the computer hangs and no error is displayed, continue at step 7 on page 91.
7. Run the Diagnostic programs. See “Diagnostics” on page 88.
• If you receive an error, replace the part that the diagnostic program calls out.
• If the test stops and you cannot continue, replace the last device tested.
Problem determination tips
Due to the variety of hardware and software combinations that can be encountered, use the following
information to assist you in problem determination. If possible, have this information available when
requesting assistance from Service Support and Engineering functions.
• Machine type and model
• Processor or hard disk drive upgrades
• Failure symptom
– Do diagnostics indicate a failure?
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