Classic Computer Magazine Archive COMPUTE! ISSUE 128 / APRIL 1991 / PAGE 14

Is there a doctor in the house: quick cures for sick systems. (includes related articles on troubleshooting PC problems)
by Tony Roberts

In recent years, we've grown to count on our cars and our computers. Although both are more reliable now than in years past, both still break down. Most people, however, are better equipped to handle a malfunctioning car than a misbehaving computer. In most cases, computer problems aren't serious. A reasonably quick and inexpensive repair for most malfunctions is possible, provided you know what to look for and what to do. Experience is a good teacher, and this article will help give you a head start on that experience.

Power On!

Each time you switch on your system, it quickly runs through a series of tests that evaluate the hardware and make sure everything's operating properly. The disk drives spin briefly, you hear a beep, and a memory test is run.

In most cases, the system passes this Power-On Self Test (POST), and the computer dives into the AUTO-EXEC.BAT file. By the time you look up from your desk calendar, the system is ready for you to begin work.

Sometimes, though, there's a problem. Perhaps you're brought to attention by a series of strident beeps, or maybe nothing happens at all.

If your system is totally unresponsive, start playing detective, and start with the obvious. Is everything plugged in? Is the power strip turned on? Are the brightness and contrast switches on the monitor adjusted properly?

If the computer noisily informs you that there is trouble, the number of beeps you hear is your clue to where the problem is. To decipher the beeps, however, you'll need the manual that came with your system.

The POST is part of your system's BIOS, and BIOS manufacturers are not consistent will all error messages and codes. The manual may have an appendix titled something like "Troubleshooting," which often can help you isolate problems.

Stop, Look, Listen

If the cables outside the machine are snug, listen for the PC's fan when you switch on the machine. If the fan isn't turning, check the back panel for a 110/220-volt selector switch, and make sure it's set properly (most likely 110 volts) for the power you're using. If the fan runs but the system doesn't operate, it's time to open up the case and check the internal connections. (See "Working Inside Your PC" for instructions on how to safely open up and make internal adjustments to your computer.)

Check the connections from the power supply to the system board and from the power supply to the disk drives. Check the disk drive data cable connections on the disk drives and the disk controller. Check to see that all boards in the system are properly seated in the slots on the mother-board. And make sure all memory and system chips are snug in their positions.

If you have an AT-class computer, sooner or later you'll experience a CMOS RAM failure. CMOS RAM is a bit of memory, backed up by batteries that remembers the system time and configuration. When the batteries run down, the data stored in CMOS RAM will be lost, and the system won't know how to boot itself. You may receive a warning of an impending CMOS RAM failure if your system clock loses time rapidly when the power is shut off. In other cases, CMOS RAM fails suddenly.

To correct the problem, run the setup program and give the computer all the information it needs to know about memory, disk drives, monitors, and the time and date. The computer will reboot, and everything will be fine until you shut it off again.

On most systems, the setup program is part of the system BIOS and is activated by a special key combination such as Ctrl-Alt-S. On some systems, the setup program is a separate program that can be kept in your hard disk's DOS directory and on a separate boot disk that can be used to start the system if it's impossible to access the hard disk.

If you had CMOS RAM problems today, chances are you'll experience the same trouble tomorrow and every day until you replace the batteries have worn down. There are several different battery configurations used to power CMOS RAM. Some systems use one or two lithium batteries; others use four standard 1.5-volt AA batteries. Lithium batteries last far longer than AA batteries, but they're correspondingly more expensive.

The next time you have your system open, note the type of batteries used to power CMOS RAM. That way you'll be able to buy the correct replacement easily when your battery starts to fail.

Some systems are built with a lithium battery soldered into place on the motherboard. Such motherboards also include a connection for an external battery should the original fail. Refer to your system documentation for the location of the connector and the jumper that needs to be switched to activate the external power source.

Software Solutions

Although this article deals mainly with hardware problems, don't overlook software as the culprit if your system starts misbehaving. If your machine starts acting erratically while you're at work, save your files and reboot the system. In most cases, a reboot will clear the problem.

Another behavioral problem might result from conflicting memory resident utility programs. If you've recently added or upgraded your software in some way, you may have unknowingly added a conflict. Getting software to work together is a balancing act.

System software sometimes gets corrupted, and it can happen in a variety of ways. An electrical glitch can damage an important file, or an illmannered software installation program can throw a monkey wrench into your system. It's good insurance to make a boot disk that contains the system files of the DOS version you normally use, as well as copies of AUTOEXEC.BAT, CONFIG.SYS, any driver files installed by CONFIG.SYS, and important DOS commands (such as SYS, FORMAT, FDISK, and CHKDSK). Put the disk aside and use it only as a backup if your system appears to be corrupted.

Damaged data files also cause difficulties. Data files may become damaged when a program is terminated unexpectedly, such as when the power fails or a user simply shuts off the machine and heads home without exiting the program properly. A database that is suddenly unable to locate data may suffer from this problem. The DOS utility CHKDSK can identify and correct files whose pointers are no longer accurate. Running CHKDSK or a similar program regularly can help prevent this type of problem from popping up.

Hard Life

One of the most sickening moments in a computer user's life is the time the hard disk won't boot. At that moment, all your work hangs in the balance. Has the hard disk gone bad, or is it just resting?

First, try powering down the machine, waiting several seconds, and then rebooting. If there still no response, boot the system using your boot disk; then, after the system is running, try to access your hard disk. If the system won't boot from a floppy disk either, your have a possible controller failure. Open the system and reseat the controller board; then try again.

If you're able to operate normally after booting from a floppy, your system has lost some of the information it needs to get going. If you see a message indicating there's been a boot disk failure, run setup to make sure the hard disk type is properly set.

If you receive the message Non-system Disk, the information that tells the system that the hard disk is a bootable device has been lost. To correct this problem, attempt to restore the system files by using the DOS SYS command from your boot floppy. If that fails, you can usually restore a disk to service by backing up all the data on the hard drive, reformatting the drive, installing new system files, and restoring the data files.

An easier solution that either of the above might be to run a disk utility program such as Norton Disk Doctor (from The Norton Utilities) to identify the problem and make repairs. If you have such a program handy, it can save you time and put you back to work with the confidence that the problem has been corrected.

If you have booted from the floppy disk but are unable to access the hard drive at all, you may be due for a drive replacement. Put your ear close to your machine and listen for the sound of the hard disk spinning. If you're not sure whether you hear the disk or the fan, switch off the power. The fan will stop spinning quickly while the hard disk will take several seconds to come to a stop. Similarly, when you turn on the power, you should be able to differentiate between the fan and the disk.

If the hard disk is not spinning, open the machine and check the power supply cable. If the power is properly connected but the hard disk does not spin, plan to buy a new one.

Sometimes it's possible to coax a reluctant drive into spinning up one more time by powering the system off and on a few times. If the drive comes back to life, though, don't expect it to last long. Back up all of your data now, and make arrangements to replace the disk. If you can't get the disk going again, all is not lost. A computer repair center may be able to get the drive going long enough to recover your data for you. If not, you'll have to rely on your backups, so make sure they're up to date.

Key Points

Another problem that plagues computer owners is a failure of the keyboard or one or more of its keys. If the entire keyboard is unresponsive, check to see that it's plugged in. Also consider whether someone has locked the keyboard with the key lock on the system unit.

Be aware that keyboards for XT- and AT-style computers differ. Many AT-style computers differ. Many keyboards, however, have a switch on the underside that allows one keyboard to be used with either type of system. If your keyboard has such a switch, make sure it's properly set.

If another computer system is available, try exchanging keyboards with it. If your keyboard fails on the other system, the problem is either in your keyboard or in the cable, with the cable being the most likely source of the problem. If your keyboard works on the other system but the other system's keyboard does not work on yours, the problem may be in the keyboard connector; and that would require a trip to the service center.

If only one or two keys are giving you trouble, you may be able to correct the problem with a little cleaning. First, grasp the offending key cap and attempt to pull it straight up and off of the key switch. If you are unable to remove the key cap with gentle pressure, try using a small screwdriver to gently pry the key cap off. If you continue to meet resistance, stop! Some key caps are not designed to be removed.

If you can remove the key cap, examine the area around the key switch for debris of dust. Use a cotton swab dipped in denatured alcohol to clean the area. In many cases, dirt or crumbs can interfere with the operation of the switch and can keep it from making proper electrical contact.

If you're unable to remove the key cap, you can perform the same cleaning operation, but you'll have to open the keyboard to do it. Turn off the computer and unplug the keyboard. Turn it upside down and set it on a soft surface, such as a towel. Remove the screws on the keyboard's bottom, and separate its top and bottom halves.

If the keyboard assembly is secured to the bottom half of the case, you'll be able to examine the area under the key caps and to use your cotton swab to brush away dirt. Otherwise, remove the screws that hold the keyboard to the top half of the case, lift out the keyboard, and then perform your cleaning.

If you're unable to get your keyboard working again, plan to buy a replacement Few repair shops even attempt to fix a broken keyboard. Replacements are inexpensive, and chances are you can find a keyboard that's much more comfortable than the one that came with your system.

Northgate and Zeos replacement keyboards have excellent reputations, and you'll be able to get a new one for less than $100. When ordering a replacement, you can choose whether the function keys are on top or along the left side. You can buy models that click when you type, and if your office is cramped, you can find reduced-size keyboards that take up a little less precious desk space.

Having an idea how to trouble-shoot minor system problems is a real confidence builder for computer users. Keep a log of your troubleshooting activities. Make notes of the troubles your computer experiences and how you solve the problems. Such records can be handy when your neighbors and office mates start calling on you to diagnose their computer ills.