CompTIA A+ Certification

Troubleshooting is perhaps the most difficult task of a computer technician. Frequently, the problems reported are just symptoms, not the cause. It takes investigation to pinpoint the real cause. After you diagnose a problem, you must develop a plan of action to correct the problem. To efficiently and effectively troubleshoot a problem, you must approach the problem in an organized and methodical manner, eliminating as many possible causes so that you can focus on the real cause of the problem. To do this, you must be organized.

The first part in approaching a troubleshooting problem is to completely understand the problem in its entirety. This requires gathering information from the client or the computer operator. Ask a few specific questions to help identify the problem and list the events that led up to the failure. It is often a good idea to examine the computer and verify the client's statements as much as possible. Access to documentation that came with the computer system can also be a valuable source of troubleshooting information as they often contain a list of compatible replacement parts and exploded diagrams of the model being repaired. If the client does not have a copy of the documentation that came with the computer, check the computer manufacturer or vendor's Web site. Also check if the Web site has a Frequently Asked Questions section, this may contain several pieces of information that can be very valuable and might even lead to a possible solution if there is a specific question or problem that relates to your situation.

Next, attempt to isolate the problem by eliminating any obvious possible causes working from the simplest possible cause to the more complex. Table 4.2 provides 14 possible categories you can use to isolate the problem.

Isolating the Problem
Category	Symptom	Possible Cause
Electrical power	Computer will not boot	Power connectors
	Intermittent errors POST	Plugs and cords
	Intermittent lock ups	Power supply
	Devices not working or not detected	Fuse box Wiring Electric utility
Connectivity	Device not working or not detected	External cables
	Intermittent errors on a device	Internal cables
	Device failure or failure to boot	Properly seated cards SCSI chain
		Front panel wiring
Boot	Computer will not boot	Boot ROM
	Consistent errors on POST	All products on the hardware
	Beep errors	abstraction layer list
	CMOS text errors, hard disk drive,	CMOS
	floppy disk drive, and video errors	CMOS battery Flash ROM
Memory	Computer will not boot	Improper RAM type and
	Parity errors	setup
	General Protection Fault with	RAM CMOS settings
	consistent addresses HIMEM.SYS errors	Motherboard jumper settings
Mass storage	Error messages:	Hard disk drives, floppy disk
	Missing Operating System	drives, CD-ROM drives Zip
	File Not Found	drives, tape drives
	No Boot Device	Partitions
	Abort, Retry, Fail	File structure File allocation tables
		Directory structure
		Filenames and attributes
Input/output (I/O)	System locks up	IRQ settings
	Device not responding	I/O address
	Bizarre behavior from a device	DMA settings
		Serial port settings
		Parallel port settings
		SCSI settings
		Card jumper settings
Operating system	Error messages:	BUFFERS
	Missing Operating System	FILES
	Bad Or Missing Command	File Control Blocks
	Interpreter	Stacks
	Insert Disk With COMMAND.COM	IO.SYS/MSDOS.SYS
	Stack Overflow	Set statements
	Insufficient File Handles	Paths and prompts
		External MS-DOS
		commands
		Multiboot CONFIG.SYS
Applications	Application does not work properly	Improper installation
	Application-specific errors	Improper configuration
	Application-specific General	Software incompatibilities
	Protection Faults
	Lock ups only in specific application
Device drivers	Device lock ups on access	All devices in the Windows
	Intermittent lock ups	Registry, .ini files,
	Computer runs in safe mode only	CONFIG.SYS,
		SYSTEM.INI, called in
		AUTOEXEC.BAT
		Improper versions
		Improper configuration
Memory	Not Enough Memory error	HIMEM.SYS settings
management	Missing extended memory	EMM386.EXE settings
	specification and Expanded Memory	MSDOS.SYS options
	Specification	SYSTEM.INI/WIN.INI
	Device lock ups	Virtual memory
	General Protection Faults at	Windows resource usage
	KRNL386.EXE	Upper Memory Block
	General Protection Faults at	management
	USER.EXE or GDI.EXE
Configuration	Programs refuse execute command	Files used for initialization
setup	Missing options in program	Basic layout of initialized
	Missing program or device	files
Viruses	Computer is slow	Virus problems
	Failure to boot or intermittent lock
	ups
	Storage problems
	Operating-system problems
	Mysterious symptoms
Network	Logon errors	User password problem
	Communication errors	Expired password
		Cable or NIC problems

Intermittent problems are the most difficult ones to isolate. The only way to resolve them is to re-create the set of circumstances that causes the failure.

Note: For a totally random, intermittent problem, and for intermittent reboots, always suspect a faulty power supply.

Once you have isolated the cause you should be able to identify the problem by eliminating the possible causes. Once you have located the problem, either repair or replace the defective part. If the problem is software-oriented, be sure to record the software setting be attempting to reinstall or update the software system. Make sure that your repair has solved the problem. This involves two steps: making sure that the problem no longer exists; and make sure that the repair did not create other problems Finally, document the problem and the repair. This will be quite useful when encountering a similar problem in the future.