Hardware Troubleshooting Techniques - Pearson UK

1 Hardware TroubleshootingTechniquesIntroductionThi s chapter contains information that applies to identifying and trouble - shooting Hardware Hardware /Software/Configuration ProblemsOne of the first steps in Troubleshooting a computer problem (or any otherprogrammable system problem ) is to determine whether the problem is dueto a Hardware failure or to faulty software. In most PCs, you can use a sig-nificant event that occurs during the startup process as a key to separatehardware problems from software problems: the single beep that most PCsproduce between the end of the power-on self test (POST) and the begin-ning of the startup that occur, or are displayed, before this beep indicate that a hardwareproblem of some type exists.

2 Up to this point in the operation of the system,only the BIOS and the basic system Hardware have been active. The operat-ing system side of the system does not come into play until after the 0789732769 CH03 8/31/04 12:54 PM Page 3178If the system produces an error message (such as The system has detectedunstable RAM at location x ) or a beep code before the single beep occurs,the system has found a problem with the Hardware . In this case, a bad RAMmemory device is , if the startup process reaches the point at which the system sCMOS configuration information is displayed onscreen, you can safelyassume that no Hardware configuration conflicts exist in the system s basiccomponents.

3 After this point in the bootup process, the system begins load-ing drivers for optional devices and additional the error occurs after the CMOS screen displays and before the bootuptone, you must clean boot the system and single-step through the remainderof the bootup can still group errors that occur before the beep into two distinct cate-gories: Configuration errors Hardware failuresA special category of problems tends to occur when a new Hardware optionis added to the system, or when the system is used for the very first problems are called configuration problems, or setup problems. Theseproblems result from mismatches between the system s programmed config-uration held in CMOS memory and the actual equipment installed in is usually necessary to access the system s CMOS setup utility in the fol-lowing three situations: When the system is first constructed.

4 When it becomes necessary to replace the CMOS backup battery on thesystem board. When a new or different option is added to the system (such as memorydevices, hard drives, floppy drives, or video display), it might be neces-sary to access the setup utility to accept the changes that have most systems, the BIOS and operating system use plug-and-play tech-niques to detect new Hardware that has been installed in the system. Thesecomponents work together with the device to allocate system resources forthe device. In some situations, the PnP logic is not able to resolve all the sys-06 0789732769 CH03 8/31/04 12:54 PM Page Troubleshooting Techniques179tem s resource needs and a configuration error occurs. In these cases, the usermust manually resolve the configuration you are installing new Hardware or software options, be aware of thepossibility of configuration errors occurring.

5 If you encounter configuration(or setup) errors, refer to the installation instructions found in the new com-ponent s installation/user you cannot confirm a configuration problem , you most likely have a defec-tive component. The most widely used repair method involves substitutingknown-good components for suspected bad components. Other alternativesfor isolating and correcting a Hardware failure that appears before the boot-up depend on how much of the system is , symptoms can be divided into three sections: configuration prob-lems, bootup problems, and operational system s configuration settings are normally checked first. It is impor-tant to observe the system s symptoms to determine in which part of the sys-tem s operation the fault occurs.

6 The error messages described in Table errors that occur and are reported before the single beep tone is pro-duced at the end of the POST Common Configuration Error CodesAfter the beep tone has been produced in the startup sequence, the systemshifts over to the process of booting up and begins looking for and loadingthe operating system. Errors that occur between the beep and the presenta-tion of the operating system s user interface (command prompt or GUI) gen-erally have three possible sources. These sources are summarized in the fol-lowing list that includes the typical error messages associated with eachsource. Hardware failure (physical problem with the boot drive) General Failure Error Reading Drive x06 0789732769 CH03 8/31/04 12:54 PM Page 3180 Corrupted or missing boot files Bad or Missing Command Interpreter Nonsystem Disk or Disk Error Bad File Allocation Table Corrupted or missing operating system filesBoth configuration problems and bootup problems can be caused by a hard-ware or operational failure.

7 If the configuration settings are correct, butthese symptoms are present, a Hardware problem is indicated as the cause ofthe problem . Conversely, bootup problems are typically associated with theoperating Troubleshooting ToolsThe level of Troubleshooting most often performed on PC Hardware isexchangingField Replaceable Units(FRUs). Due to the relative low cost ofcomputer components, it is normally not practical to troubleshoot failedcomponents to the IC level. The cost of using a technician to diagnose theproblem further, and repair it, can quickly exceed the cost of the new replace-ment , a few Hardware diagnostic tools can be very helpful in isolatingdefective Hardware components.

8 These tools include Software diagnostic disk Multimeter Cable tester POST cardSoftware Diagnostic PackagesSeveral commercially available disk-based diagnostic routines can check thesystem by running predetermined tests on different areas of its diagnostic package evaluates the response from each test and attemptsto produce a status report for all of the system s major components. Like thecomputer s self-tests, these packages produce visual and beep-coded errormessages. Figure depicts the Main menu of a typical self-booting soft-ware diagnostic 0789732769 CH03 8/31/04 12:54 PM Page Troubleshooting Techniques181 Figure typical software diagnostic main menu is the gateway to information about the system s makeup andconfiguration, as well as the entryway to the program s Advanced DiagnosticTest functions.

9 You can find utilities for performing low-level formats onolder hard drive types and for managing small computer system interface(SCSI) devices through this menu. In addition, options to print or show testresults are available here, as is the exit point from the most common software- Troubleshooting packages test the system smemory, microprocessor, keyboard, display monitor, and the disk drive sspeed. If at least the system s CPU, disk drive, and clock circuits are working,you might be able to use one of these special software- Troubleshooting pack-ages to help localize system failures. They can prove especially helpful whentrying to track down non-heat-related intermittent a diagnostic program indicates that multiple items should be replaced,replace the units one at a time until the unit starts up.

10 Then replace any unitsremoved prior to the one that caused the system to start. This processensures that there are not multiple bad parts. If you have replaced all theparts, and the unit still does not function properly, the diagnostic software 0789732769 CH03 8/31/04 12:54 PM Page 3182 Using a Multimeter in a PCA number of test instruments can help you isolate computer Hardware prob-lems. One of the most basic pieces of electronic Troubleshooting equipmentis the multimeter. These test instruments are available in both analog anddigital readout form and can be used to directly measure electrical values ofvoltage (V), current in milliamperes (mA) or amperes (A), and resistance inohms. Therefore, these devices are referred to as VOMs (volt-ohm-milliammeters) for analog types, or DMMs (digital multimeters) for depicts a digital multimeter.