Motherboard and CPU Problems

Most motherboard and CPU problems manifest themselves by the system appearing completely dead. However, “completely dead” can be a symptom of a wide variety of problems, not only with the CPU or motherboard but also with the RAM or the power supply. So, a POST card (described in the preceding section) may be helpful in narrowing down the exact component that is faulty.

When a motherboard fails, it is usually because it has been damaged. Most technicians cannot repair motherboard damage; the motherboard must be replaced . Motherboards can become damaged due to physical trauma, exposure to electrostatic discharge (ESD), or short-circuiting . To minimize the risk of these damages, observe the following rules:

• Handle a motherboard as little as possible, and keep it in an antistatic bag whenever it is removed from the PC case.

• Keep all liquids well away from the motherboard, because water can cause a short circuit.

• Wear an antistatic wrist strap when handling or touching a motherboard.

• When installing a motherboard in a case, make sure you use brass stand-offs with paper washers to prevent any stray solder around the screw holes from causing a short circuit with the metal of the screw.

A CPU may fail because of physical trauma or short-circuiting, but the most common cause for a CPU not to work is failure to install it properly. With a PGA-style CPU, ensure that the CPU is oriented correctly in the socket. With an SECC-style CPU, make sure the CPU is completely inserted into its slot.

I/O Ports and Cables

I/O ports include legacy parallel and serial, USB, and FireWire ports, all of which are used to connect external peripherals to the motherboard. When a port does not appear to be functioning, check the following:

• Cables are snugly connected.

• The port has not been disabled in BIOS Setup.

• The port has not been disabled in Device Manager in Windows.

• No pins are broken or bent on the male end of the port or cable being plugged into it.

If you suspect that the cable, rather than the port, may be the problem, swap out the cable with a known-good one. If you do not have an extra cable, you can test the existing cable with a multimeter by setting it to ohms and checking the resistance between one end of the cable and the other.

Use a pin-out diagram, if available, to determine which pin matches up to which at the other end. There is often—but not always—an inverse relationship between the ends. In other words, at one end pin 1 is at the left, and at the other end it is at the right on the same row of pins.

Cooling Issues

A PC that works for a few minutes and then locks up is probably experiencing overheating due to a heat sink or fan not functioning properly. To troubleshoot overheating , first check all fans inside the PC to ensure they are operating, and make sure that any heat sinks are firmly attached to their chips.

In a properly designed, properly assembled PC case, air flows in a specific path from the power supply fan through the vent holes. Cases are designed to cool by making the air flow in a certain way. Therefore, operating a PC with the cover removed can actually make a PC more susceptible to overheating, even though it is “getting more air.”

Similarly, operating a PC with empty expansion slot backplates removed can inhibit a PC’s ability to cool itself properly because the extra holes change the airflow pattern from what was intended by its design.

Although CPUs are the most common component to overheat, occasionally chips on other devices, particularly video cards, may also overheat. Extra heat sinks or fans may be installed to cool these chips.

Case Issues

A PC case holds the drives in its bays, holds the power supply, and has lights and buttons on the front. For the first two of those functions, simply make sure that the drives and the power supply are tightly fastened in the case with screws .

If one of the lights or buttons on the front of the PC is not functioning, remove the cover and check the wires that run from the back of that button/light to the motherboard. If the wire has become detached, reattach it. Refer to the motherboard manual or the writing on the motherboard itself to determine what goes where.

Hard Disk System Problems

Hard disk system problems usually stem from one of three causes:

• The adapter (that is, the IDE or SCSI interface) is bad.

• The disk is bad.

• The adapter and disk are connected incorrectly.

The first and last causes are easy to identify, because in either case the symptom will be obvious: The drive won’t work. You simply won’t be able to get the computer to communicate with the disk drive.

However, if the problem is a bad disk drive, the symptoms aren’t as obvious. As long as the BIOS POST routines can communicate with the disk drive, they are usually satisfied. But the POST routines may not uncover problems related to storing information. Even with healthy POST results, you may find that you’re permitted to save information to a bad disk, but when you try to read it back you get errors. Or the computer may not boot as quickly as it used to, because the disk drive can’t read the boot information successfully every time.

In some cases, reformatting the drive can solve the problems described in the preceding paragraph. In other cases, reformatting brings the drive back to life only for a short while. The bottom line is that read and write problems usually indicate that the drive is malfunctioning and should be replaced soon.

Modem Problems

The most common peripheral problems are those related to modem communications. The symptoms of these problems include the following:

• The modem won’t dial.

• The modem keeps hanging up in the middle of the communications session.

• The modem spits out strange characters to the terminal screen.

If the modem won’t dial, first check that it has been configured correctly in Windows, including its resource assignments.

Some modems work only under Windows because some of their functions rely on Windows software; these are called Winmodems or software modems . If such a modem does not work immediately upon installation, try running the Setup software that came with the modem.

If the configuration is correct, and Windows recognizes the modem, it should work for dial-up networking connections.

AT Commands

When you’re using a terminal application such as HyperTerminal, it is important to use the correct initialization commands. These are the commands sent to the modem by the communications program to initialize it. These commands tell the modem such things as how many rings to wait before answering, how long to wait after the last keystroke was detected for it to disconnect, and at what speed to communicate.

Modem initialization commands are known as the Hayes command set or the AT command set , because each Hayes modem command started with the letters AT (presumably calling the modem to ATtention).

Each AT command does something different. The letters AT by themselves ask the modem if it’s ready to receive commands. If it returns OK , the modem is ready to communicate. If you receive Error , there is an internal modem problem that may need to be resolved before communication can take place.

Table 2.1 lists a few of the most common AT commands, their functions, and the problems they can solve. You can send these commands to the modem by opening a terminal program like Windows Terminal or HyperTerminal and typing them in. All commands should return OK if they were successful.

If two computers can connect, but they both receive garbage on their screens, there’s a good chance that the computers don’t agree on the communications settings. Settings such as data bits, parity, stop bits, and compression must all agree in order for communication to take place.

Keyboard and Mouse Problems

Usually, keyboard problems are environmental. Keyboards get dirty, and the keys start to stick.

One way to clean a keyboard is with the keyboard cleaner sold by electronics supply stores. This cleaner foams up quickly and doesn’t leave a residue behind. Spray it liberally on the keyboard and keys. Work the cleaner in between the keys with a stiff toothbrush. Blow away the excess with a strong blast of compressed air. Repeat until the keyboard functions properly. If you have to clean a keyboard that’s had a soft drink spilled on it, remove the key caps before you perform the cleaning procedure; doing so makes it easier to reach the sticky plungers.

Similarly, most mouse problems, such as the pointer failing to move in one direction or the other, or the pointer jumping around onscreen, are due to dirt building up inside the mouse. To clean a standard mouse, remove the plate on the bottom of the mouse that holds the ball in place; then remove the ball and clean the inside chamber with an alcohol-dipped cotton swab. Clean the ball itself with mild soap and water. Do not use alcohol on the ball, because it tends to dry out the rubber.

Display System Problems

There are two types of video problems: no video and bad video. No video means no image appears on the screen when the computer is powered up. Bad video means the quality is substandard for the type of display system being used.

No Video

Any number of things can cause a blank screen. The first three are the most common: the power is off, the monitor’s cable is unplugged, or the contrast or brightness is turned down.

If you’ve checked the power as well as the brightness and contrast settings, then the problem could be a bad video card or a bad monitor. Most monitors these days display a Working message briefly when you turn them on, so you can ascertain that the monitor is working and that an amber light appears on the front. When the PC starts up, the light on the front of the monitor changes from amber to green, indicating that the monitor is receiving a signal.

If the monitor is working but not receiving a signal from the PC, the video card may be bad. However, no video can also mean a problem with the motherboard, RAM, or CPU, so it is not a given that the video card is at fault when no video appears.

Malfunctioning monitors are usually not worth fixing, because the cost of the labor involved exceeds the cost of a brand-new monitor. In addition, it may be difficult to find a technician to work on a monitor, because it is not part of most standard PC technician training programs (due to the risk of electric shock from the high-voltage capacitor inside the monitor).

Bad Video

A monitor that does not display one of the three basic colors (red, green, or blue) probably has a bad cable, a bent or broken pin, or a loose connection at either the PC or the monitor. This is the case because different pins on the connectors—and wires in the cable—control different colors.

Color problems may also result from the monitor being out of adjustment. With most new monitors, this is an easy problem to fix. Old monitors had to be partially disassembled to change these settings. New monitors have push-button control panels for changing these settings.

Exposure to a magnetic field can cause swirls and fuzziness even in high-quality monitors. The Earth itself generates magnetic fields, as do unshielded speakers and power surges. Most monitors have metal shields that can protect against magnetic fields. But eventually these shields can get polluted by taking on the same magnetic field as the Earth, so they becomes useless. To solve this problem, these monitors have a built-in feature known as Degauss . This feature removes the effects of the magnetic field by creating a stronger magnetic field with opposite polarity that gradually fades to a field of zero. A special Degauss button or feature in the monitor’s on-screen software activates it. You need only press it when the picture starts to deteriorate. The image will shake momentarily during the Degauss cycle, and then return to normal.

Floppy and Other Removable Disk Drive Problems

Most floppy-drive problems result from bad media. Your first troubleshooting technique with floppy-drive issues should be to try a new disk.

One of the most common problems that develops with floppy drives is misaligned read/write heads. The symptoms are fairly easy to recognize—you can read and write to a floppy on one machine but not on any others. This is normally caused by the mechanical arm in the floppy drive becoming misaligned . When the disk was formatted, it was not properly positioned on the drive, thus preventing other floppy drives from reading it.

Numerous commercial tools are available to realign floppy drive read/write heads. They use a floppy drive that has been preformatted to reposition the mechanical arm. In most cases, though, this fix is temporary—the arm will move out of place again fairly soon. Given the inexpensive nature of the problem, the best solution is to spent a few dollars and replace the drive.

Another problem you may encounter is a phantom directory listing. For example, suppose you display the contents of a floppy disk, and then you swap to another floppy disk but the listing stays the same. This is almost always a result of a faulty ribbon cable; a particular wire in the ribbon cable signals when a disk swap has taken place, and when that wire breaks, this error occurs.

Sound Card Problems

Sound cards are traditionally one of the most problem-ridden components in a PC. They demand a lot of PC resources and are notorious for being very inflexible in their configuration. The most common problems related to sound cards involve resource conflicts (IRQ, DMA, or I/O address). The problem is much less pronounced on PCI than on ISA cards.

Luckily, most sound-card vendors are quite aware of the problems and ship very good diagnostic utilities to help resolve them. Use your PC troubleshooting skills to determine the conflict, and then reconfigure until you find an acceptable set of resources that are not in use.

Some sound cards are not completely Plug-and-Play compatible. Windows might detect that new hardware has been installed, but be unable to identify the new hardware as a working sound card. To fix this problem, run the Setup software that came with the sound card.

CD-ROM/DVD Issues

CD-ROM and DVD problems are normally media related. Although compact disc technology is much more reliable than floppy disks, it is still not perfect. Another factor to consider is the cleanliness of the disc. On many occasions, if a disc is unreadable, simply cleaning it with an approved cleaner and a lint-free cleaning towel will fix the problem.

If the operating system does not see the drive, start troubleshooting by determining whether the drive is receiving power. If the tray will eject, you can assume there is power to it. Next , check BIOS Setup (for IDE drives) to make sure the drive has been detected. If not, check the Master/Slave jumper on the drive and make sure that the IDE adapter is set to Auto, CD-ROM, or ATAPI in BIOS Setup.

In order to play movies, a DVD drive must have MPEG decoding capability. This is usually accomplished via an expansion board, but it may be built into the video card or sound card, or it may be a software decoder. If DVD data discs will play but not movies, suspect a problem with the MPEG decoding.

If a CD-RW or DVD drive works normally as a regular CD-ROM drive but does not perform its special capability (does not read DVD discs, or does not write to blank CDs), perhaps software needs to be installed to work with it. For example, with CD-RW drives, unless you are using an operating system such as Windows XP that supports CD writing, you must install CD writing software in order to write to CDs.

Network Interface Card

In general, network interface cards (NICs) are added to a PC via an expansion slot. The most common issue that prevents network connectivity is a bad or unplugged patch cable.

Cleaning crews and the rollers on the bottoms of chairs are the most common threats to a patch cable. In most cases, wall jacks are placed 4 to 10 feet away from the desktop. The patch cables are normally lying exposed under the user’s desk, and from time to time damage is done to the cable or it is inadvertently snagged and unplugged. When you troubleshoot a network adapter, start with the most rudimentary explanations first. Make sure the patch cable is tightly plugged in, and then look at the card and see if any lights are on. If there are lights on, use the NIC’s documentation to help troubleshoot. More often than not, simply shutting down the machine, unplugging the patch and power cables for a moment, and then reattaching them and rebooting the PC will fix an unresponsive NIC.

BIOS Issues

Computer BIOSes don’t really go bad; they just become out-of-date. This is not necessary a critical issue—they will continue to support the hardware that came with the box. It does , however, become an issue when the BIOS doesn’t support some component that you would like to install—a larger hard drive, for instance.

Most of today’s BIOSes are written to an EEPROM and can be updated through the use of software. Each manufacturer has its own method for accomplishing this. Check out the documentation for complete details.

Power Supply Problems

Power supply problems are usually easy to troubleshoot. The system does not respond in any way when the power is turned on. When this happens, open the case, remove the power supply, and replace it with a new one.

Be aware that different cases have different types of on/off switches. The process of replacing a power supply is a lot easier if you purchase a replacement with the same mechanism. Even so, remember to document exactly how the power supply was connected to the on/off switch before you remove it.

Problems with Notebook PCs

Notebook PCs have many of the same problems and solutions as desktop PCs. Most of their unique problems have to do with power.

When a battery does not hold a charge well, it is probably a Nickel Cadmium (NiCad) battery. This type of battery has a memory, so if it is not fully discharged before recharging, it fails to hold as much of a charge the next time. The solution is to replace it with a different type of battery, such as Lithium Ion, or to replace it with the same type of battery and then be careful to let it discharge each time.

When a notebook computer will not enter Standby or Hibernate mode, or will not wake up from it, suspect a conflict between the BIOS’s power management and Windows’. Disable one or the other to prevent the conflict.

An older BIOS may support the older Advanced Power Management (APM) standard rather than the newer Advanced Configuration and Power Interface (ACPI) power management. Updating the BIOS may provide the support needed for ACPI, which is more trouble-free.

In the short term , to wake up a PC that is stuck in Hibernate or Standby, try pressing and holding the Power button for 5 to 10 seconds. If this does not work, try unplugging the PC from the AC outlet and removing the batteries. Then replace the battery and turn it back on.

Sometimes an outdated video driver can cause power-management problems; updating the video driver may solve the problem.

Miscellaneous Problems

Some common problems do not fit well into categories. This section lists some common hardware issues you will be faced with.

Dislodged Chips and Cards

The inside of a computer is a harsh environment. The temperature inside the case of some Pentium computers is well over 100° F! When you turn on your computer, it heats up. Turn it off, and it cools down. After several hundred such cycles, some components can’t handle the stress and begin to move out of their sockets. This phenomenon is known as chip creep, and it can be really frustrating.

Chip creep can affect any socketed device, including ICs, RAM chips, and expansion cards. The solution to chip creep is simple: Open the case and reseat the devices. It’s surprising how often this is the solution to phantom problems of all sorts.

Another important item worth mentioning is an unresponsive but freshly unboxed PC. With the introduction of the Type II and Type II-style of processors, the number of dead boxes increased dramatically. In fact, at that time I was leading a 2,000-unit migration for a large financial institution. As with any large migration, time and manpower were in short supply. The average dead PC ratio was about 1 out of every 20. When about 10 DOAs had stacked up, I stayed after work one night to assess the problem. After checking the power supply, RAM, and cables on these integrated systems, an examination of the chip provided me with the fix. These large, top-heavy processors can become dislodged during shipment. Shortly after, manufacturers began using a heavier attachment point for the slot style of processor, which has helped tremendously.

Environmental Problems

Computers are like human beings. They have similar tolerances to heat and cold. In general, anything comfortable to us is comfortable to computers. They need lots of clean, moving air to keep them functioning.

Dirt, grime, paint, smoke, and other airborne particles can become caked on the inside of the components. This is most common in automotive and manufacturing environments. The contaminants create a film that coats the components, causing them to overheat and/or conduct electricity on their surface. Simply blowing out these exposed systems with a can of condensed air from time to time can prevent damage to the components. While you are cleaning the components, be sure to clean any cooling fans in the power supply or on the heat sink.

One way to ensure that the environment has the least possible effect on your computer is to always leave the blanks in the empty slots on the back of your box. These pieces of metal are designed to keep dirt, dust, and other foreign matter from the inside of the computer. They also maintain proper airflow within the case to ensure that the computer does not overheat.