Getting Ready and Taking Precautions






Getting Ready and Taking Precautions

Two important preparations must be made before working on the PC, regardless of what you are planning to do: ESD preparations and general surgery preparations.

 Shocking Information  A person can feel a static charge beginning at about 3,000 volts, but electronic circuits can be damaged by a charge of only 30 volts.

Avoiding shocking developments

 Shocking Information  I can’t overemphasize the importance of protecting the PC and yourself from ESD and its potential damage and hazards. You can do this in the following ways:

  • For use in emergencies only — not recommended for general use: If you are trapped inside a system case without another form of ESD protection, keep yourself in contact with the metal frame of the PC at all times.

  • The minimum precaution against ESD is to wear an antistatic wrist strap and keep the strap attached to the metal PC chassis with an alligator clip. When working inside the PC, you cannot avoid becoming a grounding circuit for static electricity that is built up in the system. The ESD strap contains a resistor that slows the discharge and protects you and the PC. In addition to wearing the ESD strap, use an antistatic mat under the PC case. That way, if you accidentally knock off the clip, you won’t pass along a charge to whatever you’re holding at the time. Several mat and strap combinations are available.

  • Keep a supply of antistatic bags on hand to protect cards and smaller FRMs outside the case. ESD lurks everywhere. Never let your guard down, and always protect your computer parts.

  • Remove the power plug from the electrical source when working on newer Pentium-class PCs. In the past, you could leave pre-Pentium PCs plugged into an AC power source, which provided a connection to an earth ground. These systems did not provide fast power-up or instant-on motherboards.

Checking in: Is the patient ready, nurse?

A year or two ago, I would have said that it’s rare for a PC repair technician to completely disassemble a PC — especially at a customer’s site. Today’s customers, however, are trying to maximize their investment in PC hardware by upgrading their older units. Replacing the motherboard, processor, power supply, and adapter cards when upgrading an older PC isn’t unusual. The information that I give you in this chapter goes beyond preparing you for the A+ Hardware Technology exam.

I use the word disassemble (and as many derivatives as I can get away with) to mean the disconnection of cables, extraction of fasteners, and removal of a module to a location outside the case — for example, onto a workbench or in a box. FRM (field-replaceable module) is used on the A+ Hardware Technology exam to refer to any component that is replaced as a whole unit and can be installed at a customer site.

 Tip  You will remember this information better if you have a PC that you can use as a model as you review this chapter. Nothing compares to hands-on experience.

Before beginning surgery on your PC, take the following actions:

  • Have your tools standing by and ready for use. If you are lucky enough to have a surgical assistant for this process, all the better — but you’re probably on your own. So, to avoid the hassle of clipping and unclipping your wrist strap (and the possibility of forgetting to clip up again) as you run off for a forgotten tool, have your tools nearby and ready to go.

  • Have paper and pen standing by so that you can write down or diagram the placement, orientation, and identifying features of the modules, cables, cards, and other vital organs that you remove. Your notes and diagrams are your guide when it’s time to reassemble the PC.

  • Use any system that works for you to sort, store, and secure the screws and other fasteners that you remove from the patient. They can easily get lost, scratch the case, or worse. (You hear an awful screeching sound if you drag the case across the workbench with a fastener trapped underneath.)

  • Gather all the support and reference disks for the devices that are installed in the PC. You may need these to reconstruct the system, especially device drivers and system resources, should you catastrophically lose the BIOS configuration settings.

Taking inventory

As a precaution against the unlikely event that you accidentally disconnect or dislodge the CMOS battery (which would unfortunately result in losing the CMOS setup information), you should boot the system and write down the system setup configuration data, such as its RAM size and its CMOS setup information.

 Warning  If you are working on a 286 or newer PC, do not disconnect the battery from the motherboard; you will lose the CMOS setup information if you do.

Before you begin to disassemble the PC, enter the CMOS setup information and record the following information:

  • Floppy disk drive size and density

  • Hard drive type and configuration in cylinders, heads, sectors, capacity, and other unique attributes, such as the landing zone (LZone)

  • RAM size by type

  • Time and date

  • Parallel port type

  • Serial port type and status

  • Other stuff that’s specific to your system

After you have written down the CMOS information, you can begin the disassembly process. Record the model and serial numbers of each major FRM as you go — especially in the shop environment.

As you reassemble the PC, verify that the parts that came out are the ones going back in. Inadvertently replacing a good part with a faulty one, and thus introducing new problems to a system, is a bad thing.

 Remember  Always close all running programs, shut down the operating system, and turn off the computer before disassembling it.



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