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Personal Computer-System Teardown and Inspection


This chapter examines procedures for tearing down and inspecting a system. The chapter describes the types of tools required, the procedure for disassembling the system, and the various components that make up the system. A special section discusses some of the test equipment you can use when troubleshooting a system; another section covers some problems you may encounter with the hardware (screws, nuts, bolts, and so on).

Using the Proper Tools

To troubleshoot and repair PC systems properly, you need a few basic tools. If you intend to troubleshoot and repair PCs professionally, there are many more specialized tools you will want to purchase. These advanced tools allow you to more accurately diagnose problems and make the jobs easier and faster. The basic tools that should be in every troubleshooter’s toolbox are:

Simple hand tools for basic disassembly and reassembly procedures, including a flat blade and Phillips screwdrivers (both medium and small sizes), tweezers, an IC extraction tool, and a parts grabber or hemostats

Diagnostics software and hardware for testing components in a system

A multimeter that allows accurate measurement of voltage and resistance

Chemicals, such as contact cleaners, component freeze sprays, and compressed air for cleaning the system

Foam swabs, or cotton swabs if foam isn’t available

Small wire ties for “dressing” or organizing wires
Some environments may also have the resources to purchase the following, although it’s not required for most work:

Memory testing machines, which are used to evaluate the operation of SIMMs (Single Inline Memory Modules), DIP (Dual Inline Pin) chips, and other memory modules

Serial and parallel wrap plugs to test serial and parallel ports

A network cable scanner, if a network is used

A serial breakout box if a lot of the systems operate over serial cables, such as UNIX dumb terminals
In addition, an experienced troubleshooter will probably want to have soldering and desoldering tools to fix bad serial cables. These tools are discussed in more detail in the following section. Diagnostics software and hardware are discussed in Chapter 21, “Software and Hardware Diagnostic Tools.”

Hand Tools

When you work with PC systems, it immediately becomes apparent that the tools required for nearly all service operations are very simple and inexpensive. You can carry most of the required tools in a small pouch. Even a top-of-the-line “master mechanics” set fits inside a briefcase-size container. The cost of these tool kits ranges from about $20 for a small service kit to $500 for one of the briefcase-size deluxe kits. Compare these costs with what might be necessary for an automotive technician. Most automotive service techs spend $5,000 to $10,000 or more for the tools they need. Not only are PC tools much less expensive, but I can tell you from experience that you don’t get nearly as dirty working on computers as you do working on cars.

In this section, you learn about the tools required to make a kit that is capable of performing basic, board-level service on PC systems. One of the best ways to start such a set of tools is a small kit sold especially for servicing PCs.

The following list shows the basic tools that you can find in one of the small PC tool kits that sell for about $20:

3/16-inch nut driver

Chip extractor

Chip inserter

Tweezers

Claw-type parts grabber

T10 and T15 Torx drivers

1/4-inch nut driver

Small Phillips screwdriver

Small flat-blade screwdriver

Medium Phillips screwdriver

Medium flat-blade screwdriver
NOTE: Some tools aren’t recommended because they are of limited use. However, they normally come with these types of kits.
You use nut drivers to remove the hexagonal-headed screws that secure the system-unit covers, adapter boards, disk drives, power supplies, and speakers in most systems. The nut drivers work much better than conventional screwdrivers.

Because some manufacturers have substituted slotted or Phillips-head screws for the more standard hexagonal-head screws, standard screwdrivers can be used for those systems.

You use the chip-extraction and insertion tools to install or remove memory chips (or other smaller chips) without bending any pins on the chip. Usually, you pry out larger chips, such as some microprocessors or ROMs, with the small screwdriver. Larger processors such as the 486, Pentium, or Pentium Pro chips require a chip extractor if they are in a standard LIF (Low Insertion Force) socket. These chips have so many pins on them that a large amount of force is required to remove them, despite the fact that they call the socket “low insertion force.” If you use a screwdriver on a large physical-size chip like a 486 or Pentium, you risk cracking the case of the chip and permanently damaging it. The chip extractor tool for removing these chips has a very wide end with tines that fit between the pins on the chip to distribute the force evenly along the chip’s underside. This will minimize the likelihood of breakage. Most of these types of extraction tools must be purchased specially for the chip you’re trying to remove.

Fortunately, motherboard designers have seen fit to use mostly ZIF (Zero Insertion Force) sockets on systems with 486 and larger processors. The ZIF socket has a lever which when raised releases the grip on the pins of the chip, allowing it to be easily lifted out with your fingers.

The tweezers and parts grabber can be used to hold any small screws or jumper blocks that are difficult to hold in your hand. The parts grabber is especially useful when you drop a small part into the interior of a system; usually, you can remove the part without completely disassembling the system.

Finally, the Torx driver is a special, star-shaped driver that matches the special screws found in most Compaq systems and in many other systems as well.

Although this basic set is useful, you should supplement it with some other small hand tools, such as:

Needlenose pliers

Vise or clamp

Small flashlight

File

Hemostats

Wire cutter or wire stripper
Pliers are useful for straightening pins on chips, applying or removing jumpers, crimping cables, or grabbing small parts.

Hemostats are especially useful for grabbing small components, such as jumpers.

The wire cutter or stripper, obviously, is useful for making or repairing cables or wiring.

The metric nut drivers can be used in many clone or compatible systems as well as in the IBM PS/2 systems, all of which use metric hardware.

The tamperproof Torx drivers can be used to remove Torx screws with the tamper- resistant pin in the center of the screw. A tamperproof Torx driver has a hole drilled in it to allow clearance for the pin.

You can use a vise to install connectors on cables and to crimp cables to the shape you want, as well as to hold parts during delicate operations. In addition to the vise, Radio Shack sells a nifty “extra hands” device which has two movable arms with alligator clips on the end. This type of device is very useful for making cables or for other delicate operations where an extra set of hands to hold something might be useful.

You can use the file to smooth rough metal edges on cases and chassis, as well as to trim the faceplates on disk drives for a perfect fit.

The flashlight can be used to illuminate system interiors, especially when the system is cramped and the room lighting is not good. I consider this tool to be essential.

Another consideration for your tool kit is an ESD (electrostatic discharge) protection kit. This kit consists of a wrist strap with a ground wire and a specially conductive mat, also with its own ground wire. Using a kit like this when working on a system will help to ensure that you never accidentally zap any of the components with a static discharge.

NOTE: You can work without an ESD protection kit, if you’re disciplined and careful about working on systems. If you don’t have an ESD kit available, you should leave the computer plugged in, so that the power cord connects the chassis of the PC to ground. Then make sure that you remain in constant or nearly constant contact with the case. It’s easy to rest an arm or elbow on some part of the case while working inside the computer.
The ESD kits, as well as all the other tools and much more, are available from a variety of tool vendors. Specialized Products Company and Jensen Tools are two of the most popular vendors of computer and electronic tools and of service equipment. Their catalogs show an extensive selection of very high-quality tools. (These companies and several others are listed in Appendix A, “Vendor List.”) With a simple set of hand tools, you will be equipped for nearly every PC repair or installation situation. The total cost of these tools should be less than $150, which is not much considering the capabilities they give you.





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