This chapter is about troubleshooting guidelines. Objectives important to this chapter are:
Concepts:The text presents a list of equipment in terms of need. The first list is considered essential tools. Note: For all tools listed, do not use magnetic tools. These can cause damage to computer equipment and media.The most needed equipment: (Some items are shown in the picture on the right. Hover over the items with your mouse for the items' names.) 
If you do not have a tool set, and can only get one, the best thing to have is a Swiss Army Cybertool. I took apart a hard drive with one to make the point that it could be done. Follow the link to see features of one model. Mouse over the components for a description of them. Equipment that it would be good to have:
The text recommends some diagnostic hardware and software. It is unlikely that the hardware will be of any use to you, unless you are actually working as a lab or bench technician. A support technician (who goes to users) will find the software of more use. The author discusses a POST (Power On Self Test) diagnostic card. Again, a good idea if you are allowed to use such a device. In a managed environment, this may not be an option. Recovery CDs are often supplied by computer vendors. They are very useful when software goes bad, but be aware that such CDs are useful only for the devices they are meant for. A recovery CD from any vendor may only be useful for the specific model or specific computer that it came with. The author offers some sound advice about any PC you are charged with maintaining (professionally or personally):
The first idea, documentation, is easy, but most people do not do it. It is easy to write down what you do and to make it a habit to write down all changes to system. It is very unusual to find anyone who does it. The second idea, making backups, is harder to do, and it is done even less often than documentation. Note that the author recommends making backup copies of your data. It is assumed that you have backup copies of your programs and operating system: they are on your original installation/recovery disks. If your system did not come with such disks, determine whether you can create them from a utility on your hard drive. You will need them when your hard drive eventually dies. Virus protection software is discussed at length in this edition of the text. Viruses can come in many forms, and by many methods. It is common to receive viruses by e-mail, but it need not be a disaster if you have a good anti-virus program running at all times, and if you receive regular updates to that program. I use Norton Internet Security at home and at work. My system at home is configured to contact Symantec (Norton's publisher) regularly, and to download updates as they become available. This is a recommended configuration. Firewall software is as important as anti-virus software, especially in environments that provide access to the Internet. The Symantec product mentioned above provides firewall protection, as does the built in program in Windows XP, although the Windows XP program only offers minimal protection from intruders. Some symptoms that might point to a virus having infected a computer:
Unfortunately, this list is neither exhaustive, nor definitive. Each of these problems could be caused by something other than a virus, and viruses are not limited to these behaviors. The best procedure to follow when a virus is suspected is to scan the machine with an updated copy of a good anti-virus program. It is often possible to scan the machine across the Internet, which assures you of getting the most current protection available from the anti-virus software publisher. (Trend Micro, the maker of PC-cillin. Symantec, the maker of Norton AntiVirus.) This is often a free service. As such, it is only valid for the scan you make at that time, so buy a copy of a good program for long term protection, and update it regularly. Some simple precautions will keep you safe from most virus infections:
The text discusses some aspects of physical care of computers. There are some other things to be aware of as well:
Computer technicians will periodically be assigned to transport, retire, and recycle computer equipment. The author provides some good advice about getting a computer ready for these activities:
Special rules apply to disposal of computer equipment, because some it contains toxic material.
The text offers a systematic approach to troubleshooting problems. In fact, it is repeated several times in the chapter, so I will try to condense it here.
When testing the problem, some general advice applies to most situations:
This edition of the text offers practical advice and illustrations for servicing a computer. Students should review this section of chapter 2 carefully, especially if they are new to the specific illustrated procedures:
Special care should be taken when removing power supplies and motherboards. Power supplies can be hazardous even when unplugged, and motherboards are difficult to remove and replace without guidance. The chapter changes topics, discussing the things that take place when a computer is started. When a computer is started (booted), the System BIOS (Basis Input Output System) runs first. This set of programs looks for hardware from which to load the operating system. The operating system provides an interface for the user to control the system. Application software allows the user to perform some sort of work, such as word processing, or creating graphic art. The BIOS can be configured to always load the operating system from the same device, or to look for it on a series of devices, should the preferred device not be present. Changing the order in which it searches for the OS on these devices is called changing the boot sequence. A technician should be able to make this kind of change to get the computer to boot from a CD, a floppy, or a USB memory device if the hard drive is not functioning properly. The way your BIOS itself is handled on the system can lead to problems. BIOS chips are ROM chips, which cannot be accessed as quickly as RAM chips, so some systems copy the BIOS to RAM on boot. This is called shadowing ROM or shadow RAM. This can be configured in the CMOS settings. You may want to change this setting (disable it) if the computer is locking up for no apparent reason. When installing new equipment, you may need to install software (which could include device drivers and application software), and you may need to set what system resources the hardware will use. Resource settings can include combinations of the following:
An IRQ is a hardware interrupt request line. There are eight, numbered from 0 through 7 on XT class machines, and sixteen of them numbered 0 through 15 on AT (or better) class machines. Assignment to an IRQ gives a device two things: the right to interrupt the processor and request service NOW, and a place in the pecking order of such assignments. 0 is always assigned to the system timer, and it has the highest priority. Other common assignments are shown below. For older devices, never assign the same interrupt number to two devices that could conceivably need attention at the same time. If possible, do not share interrupts at all. (Note that the system has already done this for IRQs 3 and 4.) However, if you are using USB (Universal Serial Bus) or PCI (Personal Computer Interconnect) devices, these devices are meant to share IRQs. More on this in a later chapter.
Direct Memory Access (DMA) channels give a device direct access to memory. An XT class machine had channels 0 through 3, later machines have 0 through 7, but you will not be able to use channel 4 since it links the upper channels to the lower ones. NT systems DO NOT want you to use this at all! I/O Addresses can be compared to a mail drop, a place in memory that the processor will check periodically. This sort of addressing is used for devices that do not need immediate attention from the CPU, whose requests can wait for a cycle or two. Devices should not share addresses, unless confusion and disaster are desired. I/O addresses can also be called ports or sockets. Memory addresses are sometimes required by a card or device on an older system. Essentially, this RAM is for the use of the device, not for communication with the CPU. The current A+ exams do not test on this concept. To examine what resources are currently in use (or available) it is suggested that you might use Microsoft Diagnostics (MSD.EXE) for DOS or Windows 9x machines, and Device Manager for computers running Windows 9x and later. The method to get to Device Manager varies a bit in each version of Windows. XP has one more step because it has moved the My Computer icon to the Start menu. (You can put it on the Desktop if you want to from its right-click menu.)
It is possible that a system problem may come from bad connection of some component. The text recommends removing and replacing components, like expansion cards, making sure that the contacts where they attach are not corroded and that no contact pins are bent or missing. Contacts on expansion cards may be cleaned with a pencil eraser, but care must be taken not to leave bits of rubber on the contacts or in sockets. It is recommended that you become familiar with the Startup Menu of Windows 9.x and later. Most users never see this menu until something goes wrong with Windows. It is possible to force the menu to appear when Windows boots up by pressing the F8 key while the screen is still black. From the Startup Menu, you may start Windows in Safe Mode, with or without network support, which will be useful in troubleshooting settings in Windows itself. It is often expedient, when having problems with specific software, to reinstall the software. It may be useful to uninstall the software first, because some installation programs check for installed components, and will not necessarily overwrite a bad or corrupted program file. You are cautioned to back up the user's data first, if at all possible. It has been common for one Windows program to cause problems with another, because such programs often install components of themselves in the Windows\System directory (or the WinNT\System32 directory, if running Windows NT). The installed components are often DLL files. DLL stands for Dynamic Link Library. A DLL file is like a collection of functions that another program can call. The problem is that one program may install its own version of a DLL file that has the same name as a DLL belonging to another program. It is more common currently for programs to install such files in their own directories, but this problem still comes up. It is suggested that the most difficult problems to solve are those that are intermittent. Neither you nor the user can predict when the next instance will be, so it is impossible to predict when to be at the user's workstation to diagnose the problem. In such cases, it may be useful to instruct the user in the proper procedure to get a screen dump of any error message he may get. If possible, the screen dump should be sent to a printer, or saved as a file. Some observations are made about keyboards. Often, a bad keyboard should simply be replaced. If necessary, the text suggests that you can rinse off spilled soft drinks, but the keyboard should dry for a couple of days before you try to use it again. I once turned a keyboard upside down, and not only did spilled coffee drip out of it, but I also saw cigarette ashes and paper clips fall onto the desk. It was a wonder that it worked at all. Several observations are made about monitor trouble. Often, the user has selected a driver or a combination of settings that do not work with with the monitor and/or video card. Starting a Windows system in Safe Mode will let you load a "plain vanilla" video driver that will work with most monitors and video cards. This will let you test possible combinations of color density, screen resolution, refresh rates, etc. You should be familiar with the procedure to change each of these settings in Windows. Printer problems are often reported by users. The problem they are having could be an incorrect driver, a printer that needs paper or toner, or a simple jam in the paper path in the printer. Some tips from this section:
A technician is cautioned to keep documentation about equipment. Not only the documentation that comes from the manufacturer, but notes about how the equipment has been configured for the worksite. It is recommended at the end of the chapter to have backup copies of both your system (and application) software, and your data files. Storing these two kinds of files on different drives is a good idea. Storing data on network servers makes sense, because the data may be backed up centrally instead of relying on a user to make copies. Fire Extinguishers - A previous edition of the text discussed use and classes of fire extinguishers at this point. Fire extinguishers are classed by the kind of fire they are able to put out. The links below will take you to sites with more information about fire classes and extinguishers. In surveying several sites, I found that there are currently at least four classes of fires, and that the symbols for them have been updated to use pictures instead of letters. Some sites list a Class K for cooking oils (Kitchen fires), but this does not seem to be universal.
Information from FEMA Information from Underwriters Laboratories Information from the University of Oklahoma Police Department In most cases, a multiclass extinguisher is preferred. On extinguishers I examined at my workplace, multiple picture symbols were used, showing the pictures for class A, B, and C. (Although they were black and white, not blue, the pictures were the same as those above.) If the extinguisher is not rated as being effective for a particular class, the symbol or picture will either be missing, or will have a diagonal line drawn through it. Water extinguishers, for example, are not effective against flaming liquids, because the flaming liquid spreads instead of being covered by the water.
While your book does not discuss it, several web sites I encountered discuss a classic explanation of fire. It may be helpful to understand this, the next time you have to put a fire out. For a fire to exist, three factors are needed:
If you can eliminate any one of these factors, the fire will go out. This is why Carbon Dioxide extinguishers work: the CO2 replaces the oxygen in the immediate vicinity of a fire, and the fire stops. Smothering a campfire works about the same way. A fire break is an example of fighting a fire by depriving it of fuel. Forest fires can be fought this way. Somewhat similarly, I once walked into a rest room in an office and found that someone had placed a roll of toilet paper on top of the light fixture over the sink. I noticed it because it was on fire. I grabbed the roll of paper and tossed it into the sink. This established a fire break. I then put out the fire on the roll of paper with water. Keeping your computer system cool, so that a fire will not ignite, is your most effective form of firefighting: don't let it start. |
