Replacing the Motherboard

Installing a new motherboard is the computer equivalent of a brain trans- plant. It’s major surgery that replaces the central components that control everything the computer does. Obviously, you won’t perform a motherboard swap very often, but if you are a truly dedicated hardware geek and you’re not afraid to tear the whole computer apart, it can be done. Just follow the instructions that come with motherboard, take your time, and double-check all the little details. As long as you pay attention to what you are doing, it isn’t that difficult. Every other component in the computer connects to the motherboard, so there are plenty of opportunities for something to go wrong. If the com- puter does not work at all after you install a new motherboard, look for these possible reasons:

Is the power supply turned on? Is the AC power connected? Are all of the power cables plugged into the motherboard? Are all of the data cables and control cables plugged into the correct out- lets and pin connectors? Are all the external components (mouse, key- board, video monitor) plugged in? Are the central processor chip and the memory modules properly mounted? Are there any loose screws or other small parts rattling around inside the case? To remove them, pick up the case, turn it upside down, and shake it. Is the bottom of the motherboard grounded to the case? Most mother- boards allow enough space for the screws and washers to keep away from the printed circuit, but sometimes they do touch part of the electrical path. Try placing an insulating fiber washer between the motherboard and each of the brass spacers that support the board inside the case. If you have trouble keeping the washers in place while you insert the screws, use a tiny dab of rubber cement to hold each washer to the bottom of the motherboard.

Power Supply Problems

The computer’s power supply converts 110V AC (or 220V outside North America and a few other places) “house current” to the lower DC voltages used by the computer’s electronic components, motors in the drives, and fans. Power supply problems can take several forms:

No AC input. If the AC power cable isn’t connected, or if the on/off switch on the back of the power supply is turned off, or if an internal fuse has blown, then the power supply won’t have any power to convert to DC. No DC outputs. With no power, the computer won’t start, the fans won’t spin, and all of the lights will remain dark. If you suspect a power supply failure, check the fans on the side of the power supply and the fans on the heat sink on top of the central processor chip. Incorrect voltages. If the voltages are too low, the electronic circuits won’t work, or if they do work, the computer restarts at random or Win- dows produces Blue Screens. If the voltages are too high, some compo- nents could be damaged. Fan malfunctions. If the fans aren’t turning, or if you see other symp- toms of a power supply problem, use a meter or a power supply tester like the one described in article 1 to check the power supply’s output voltages. If the voltages are correct, replace the fan.

Some cheap power supplies might provide all the correct voltages, but their internal components can generate radio signals that can interfere with other electronic equipment, including radios, telephones (both wired and cordless), TV sets, computer displays, and even heart pacemakers and other medical devices. If you hear a buzz on a radio or telephone when you turn on the computer, or if you see a series of horizontal lines moving across a video display, try turning your computer off and back on again. If the interference goes away when the computer is off and it comes back when it’s turned on, replace the power supply.

more of the internal components, but it’s almost never worth the time and trouble. Replacement power supplies are not expensive, and they’re likely to be more reliable than a repaired unit. When you buy a new power supply, look for one with at least the same number of watts as the old one. You can find the power rating on the label attached to the power supply’s case. To replace a power supply, follow these steps:

1. Turn off the computer.

2. Disconnect the power plug from the computer.

3. Remove the cover from the computer’s case.

4. Disconnect all of the power cables leading from the power supply to the motherboard, the hard drives, other storage devices, and components.

5. Remove the screws that hold the power supply to the case.

6. Lift the power supply out of the computer.

7. Place the new power supply in the location where you removed the old one, and replace the screws.

8. Connect the power cables to the motherboard, the drives, and the other components.

9. Plug the AC power cable into the back of the computer.

Mouse Problems

Mice and other pointing devices use a variety of technologies to transmit motion from your hand to the computer. Some are purely mechanical, with a small ball that rotates as the mouse moves, while others use a light beam or laser to track mouse motion. If the driver software is working properly, the most common cause of mouse problems is dirt.

Cleaning a Mechanical Mouse

A clean mechanical mouse uses a rubber ball to rotate three cylinders that translate motion across a flat surface (such as a table or a mouse pad) to three numeric values that the computer uses to place a cursor on the screen. As the mouse passes along the surface, it can pick up grease and dirt that can interfere with the motion of the ball and the rollers, causing them to rotate less reliably. To clean a mechanical mouse, follow these steps:

1. Turn the mouse over, and rotate the small retaining plate that holds the ball inside the housing. If it’s a trackball with the ball on top, just turn it over or turn the retaining plate.

2. Remove the ball.

3. Use a soft, moist cloth to clean the ball.

4. Look into the space that held the ball to find the three rollers. If they are not immediately visible, use a flashlight. There is probably a vertical line of dirt and other crud across each roller. Use a sharp knife (an X-Acto knife or the small blade of a Swiss Army knife work well) to scrape the dirt away from each roller. Use compressed air to remove any loose dust from inside the cavity.

5. Replace the ball and reassemble the mouse.

Cleaning an Optical Mouse

There are no moving parts in an optical mouse, so cleaning it is easier than cleaning a mechanical unit. Use a soft, damp cloth to remove all the accum- ulated dirt and gunk from the bottom of the mouse, and make sure there is nothing obstructing the light or the reflective surface.

Keyboard Problems

A computer keyboard is a mechanical device that sends electrical signals to the computer. Each key on the keyboard produces a different signal, which the computer interprets as the letter or other symbol printed on the key cap. Most keyboards are cheaply constructed assemblies that use a membrane under the plastic keys to make contact with a printed circuit board when you press a key. Some more expensive keyboards use individual switches for each key. Unless you are using an expensive ergonomic or wireless keyboard, it’s generally not worth the effort involved in trying to repair a keyboard. You should be able to find a better-quality keyboard than the ones supplied with most computers for less than $20. For a little more, you can splurge on a fancier keyboard with special features for more comfortable operation and extra keys that automate certain frequently used commands. However, there are some things you can try before you throw away your old keyboard and buy a new one. If a single key or a small group of keys stops working, the problem could be dirt between the membrane and the circuit board. Try shaking the keyboard or rapping the edge of the keyboard gently against a tabletop to dislodge the dirt. If the keys become sticky, or if somebody drops or spills food crumbs, coffee, soda, or some other form of goop into the keyboard, it’s often possible to clean it. For minor spills, a cotton swab can sometimes fit between the keys, or try using compressed air or a vacuum cleaner with a small nozzle to dislodge the stuff under the keys. For cleaning the tops and sides of the keys, the 3M No. 674 Keyboard Cleaner Kit works well, but you might accomplish the same thing with a damp cloth. For a more complete job, you can remove the character keys, use a vacuum cleaner or air hose to clean the tray, and wash the loose keys in warm soapy water.

It’s possible to remove the keys by gently prying upward with a screwdriver, but it’s a lot easier with a tool that fits around the side of a key (available from Design Components, http:// members.aol.com/capsoff). Don’t try to remove the space bar, the ENTER key, or any of the other large keys; they’re extremely difficult to reinstall. To replace each key, place it over the shaft and push down. Be sure to replace each key in the right place. For keyboards used in other countries, look at the Windows Keyboard Layouts web page at www.microsoft .com/globaldev/reference/keyboards.mspx. If you assembled your own computer, or if you bought the computer from a screwdriver shop that built it out of standard parts, you might be using a case that has more USB or FireWire sockets on the front and back of the case than the motherboard can support. When you try to install a new USB or FireWire device several months after you built the box, it’s possible that you will try to plug into to a socket that isn’t connected to the motherboard. If Windows fails to detect a USB or FireWire device when you connect it to the computer, try using a different socket. If the first socket you tried was on the front, try one on the back. If that doesn’t work, open the case and confirm that there are cables connecting the sockets on the case to sockets on the motherboard. If Windows still can’t find the device, try reinstalling the USB or FireWire driver supplied with the motherboard.