Study Guide

Electrostatic Discharge

While fixing a computer and handling electronic components, you must be careful that you do not cause any damage to the computer and its components. Therefore, it is essential that you do not cause damage from electrostatic discharge.

Concept Questions

Answer the following electrostatic discharge questions: How is electrostatic electricity generated?

Electrostatic electricity is created by the friction and separation of attractive charges, such as when you walk across a carpet on a cool, dry day.

How many volts must be built up before you feel the ESD?

3,000 volts

How many volts can damage an electronic component? 30 volts

What are the four ESD protection recommendations for preventing ESD?

1. Keep all components in antistatic bags until you are ready to install them.

2. Use grounded mats on workbenches.

3. Use grounded floor mats in work areas.

4. Use antistatic wrist straps when working on computers. How does humidity affect ESD?

If the humidity level is too low, the chance of ESD increases.

To reduce further risk of ESD, what type of clothing should you not wear?

You should not wear clothing made of silk, polyester, or wool because these fabrics are more likely to generate a static charge.

Why should the metal on the back of the wrist strap remain in contact with the skin at all times? Because the wrist strap is grounding you and not your clothing.

What should you do with sleeves and neckties when working with electronic components? Roll up your sleeves and secure your necktie.

PC Maintenance

To keep a computer running well and to extend its life, you need to perform regular maintenance. Part of the maintenance is to keep the computer clean inside and outside.

Concept Questions

Answer the following PC maintenance questions:

What can happen if a computer has an excess buildup of dirt and dust?

Dirt can cause problems with the physical operation of fans, buttons, and other mechanical components. On electrical components, an excessive buildup of dust will act like an insulator and trap the heat. This insulation will impair the ability of heatsinks and heatpipes to keep components cool, causing chips and circuits to overheat and fail.

Describe the best method to clean the following components:

1. Keyboard

Blow compressed air between the keys. Wipe the keyboard with a soft, lint-free cloth lightly moistened with water or computer-screen cleaner.

2. LCD monitor

Wipe display with a soft, lint-free cloth lightly moistened with water or LCD cleaner. You should never use glass cleaner or any type of solvent.

3. CRT monitor

To clean the screens of CRT monitors, dampen a soft, clean, lint-free cloth with distilled water and wipe the screen from top to bottom. Do not spray the glass cleaner directly onto the display.

4. Mouse

Use glass cleaner and a soft cloth to clean the outside of the mouse. Do not spray glass cleaner directly on the mouse. If cleaning a ball mouse, the ball can be removed and cleaned with glass cleaner and a soft cloth. Wipe the rollers clean inside the mouse with the same cloth. Do not spray any liquids inside the mouse.

5. Contacts on a PCI expansion card

Clean the contacts on components with isopropyl alcohol. Note that you should use the 90% or higher solution of isopropyl alcohol because some solutions in the 70-80% range contain too high a concentration of water to be effective. Do not use rubbing alcohol. Rubbing alcohol contains impurities that can damage contacts. Make sure the contacts do not collect any lint from the cloth or cotton swab. Blow any lint off the contacts with compressed air before reinstallation.

6. Removing dust and dirt from inside the computer

Use compressed air or a non-electrostatic vacuum to clean out the dust from the vents, the fan behind the vent and on the motherboard, and the heat sink and CPU heat sink. Use tweezers to remove any debris.

Power Fluctuations

Computers are designed to run off of clean DC power. Therefore, when your system experiences power fluctuations, these power fluctuations can affect the reliability and functionality of your computer.

Vocabulary Exercise: Matching

Match the definition on the left with a term on the right.

Definitions a. Complete loss of AC power. A blown fuse, damaged transformer, or downed power line can cause this.

b. Reduced voltage level of AC power that lasts for a period of time. These occur when the power line voltage drops below 80% of the normal voltage level. Overloading electrical circuits can cause this.

c. Interference from generators and lightning. This results in unclean power, which can cause errors in a computer system.

d. Sudden increase in voltage that lasts for a very short period (less than a second) and exceeds 100% of the normal voltage on a line. These can be caused by lightning strikes but can also occur when the electrical system comes back on after a blackout.

e. Dramatic increase in voltage above 110% of the normal voltage that lasts for a few seconds.



Power surge









Concept Questions

Answer the following questions about power fluctuations.

Which type of computer protection device will protect against spikes and surges?

Surge suppressors and uninterruptible power supplies

Which type of computer protection device will protect against brownouts and blackouts? Uninterruptible power supply and standby power supply

Fires and Fire Extinguishers

Computers are half mechanical, half electronic devices. As with any mechanical or electronic device, there is always a chance that a computer can catch fire. Therefore, you need to know how to handle a fire if it does occur.

Concept Questions

Answer the following questions about fires and fire extinguishers: What are the four steps in using a fire extinguisher? Step 1. P—Pull the pin.

Step 2. A—Aim at the base of the fire, not at the flames. Step 3. S—Squeeze the lever. Step 4. S—Sweep the nozzle from side to side. Identify the usage of fire extinguisher classifications.

■ Class A Paper, wood, plastics, cardboard

■ Class B Gasoline, kerosene, organic solvents

■ Class C Electrical equipment

■ Class D Combustible metals

If your computer catches on fire, which classification of fire extinguisher should you use? Class C or Class ABC

Material Safety and Data Sheets and Component Disposal

Some components and the supplies that you use to maintain computers have or are considered hazardous material. Therefore, special safety and environmental considerations exist for handling and disposing of these components and materials.

Vocabulary Exercise: Completion

Fill in the blanks with the appropriate terms about safety and disposal.

A Material Safety and Data Sheet (MSDS) is a fact sheet that summarizes information about material identification, including hazardous ingredients that can affect personal health, fire hazards, and first aid requirements. The MSDS sheet contains chemical reactivity and incompatibilities information that includes spill, leak, and disposal procedures. It also includes protective measures for the safe handling and storage of materials. To determine whether a material used in computer repairs or preventive maintenance is classified as hazardous, consult the manufacturer MSDS.

Concept Questions

Answer the following questions about MSDS and component disposal: What valuable information can be found within the MSDS?

■ The name of the material

■ The physical properties of the material

■ Any hazardous ingredients the material contains

■ Reactivity data such as fire and explosion data

■ Spill or leak procedures

■ Special precautions

■ Health hazards

■ Special protection requirements

Why do batteries need to be properly disposed of?

Batteries from portable computer systems may contain lead, cadmium, lithium, alkaline manganese, and mercury. These metals do not decay and will remain in the environment for many years. Mercury, commonly used in the manufacturing of batteries, is extremely toxic and harmful to humans.

Why do monitors need to be properly disposed of?

CRTs contain glass, metal, plastics, lead, barium, and rare earth metals. According to the U.S. Environmental Protection Agency (EPA), CRTs may contain approximately 4 pounds (1.8 kg) of lead.

What guidelines should you follow when you are disposing of batteries, monitors, and toner cartridges?

Comply with local environmental regulations.

Maintenance Safety

Because computers use electricity to operate, a danger always exists when you are fixing a computer. Therefore, you need to take certain steps to make sure that you don't get hurt and that you don't damage the computer and its components.

Concept Questions

Answer the following questions about safety:

What should you do before cleaning any device or repairing a computer? Turn off the device and unplug it from the power source.

Which two devices contain such very high voltages that you should not wear antistatic wrist straps when repairing them?

Tools of the Trade

Because computers are complicated devices that use ever-changing technology, you are not going to know everything about computers. There will be times when you need help to fix a problem. However, knowing where to get this help will greatly enhance your ability as a PC technician.

Concept Questions

Answer the following question about tools of the trade:

You just purchased a fax modem. Unfortunately, it does not include the CD or manuals. Where can you go to find the drivers and manuals?

The manufacturer's website

Study Questions

Choose the best answer for each of the questions that follow.

1. What is the correct procedure to dispose of a monitor?

A. Incineration.

B. Dispose in local landfill.

C. Consult local guidelines for disposing of hazardous material.

D. Dispose in a trash can or dumpster.

2. As a computer technician, you notice a leak in the server room. What should you do?

A. Place a bucket under the leak.

B. Call the local water department.

C. Notify building maintenance and the system administrator who is responsible for the servers.

D. Phone the janitor to clean up the water.

3. Which of the following rating of fire extinguisher should you use on a PC on fire? (Choose all that apply.)

A. Class A

B. Class B

C. Class C

D. Class ABC

4. You are going to replace faulty memory within a computer. You shut down the computer. What should you not do to avoid ESD?

B. Use an ESD strap.

C. Touch the ground of the workshop or building.

D. Touch the metal case of the power supply that is plugged in to a properly grounded outlet.

5. Wrist straps will be useful only if

A. They are plugged in to the wrist strap jack.

B. They are clean and make good skin contact.

C. The cord has not been damaged.

D. All of the above.

6. Before opening a static-shielding container or bag that contains an electronic device, you should

A. Look inside to see whether it is really sensitive.

B. Check for paperwork inside the container.

C. Ground yourself in an ESD-protected area.

D. Call the manufacturer for operating instructions.

7. Before transporting an ESD-sensitive device, it must be

A. Enclosed in a static-shielding container or bag

B. Put into a cardboard box

C. Thoroughly cleaned

D. Wrapped in newspaper

8. To prevent ESD, humidity should be kept to at least_when working on a computer.

9. How should you apply the cleaning solution to a CRT monitor?

A. A soft brush

B. A lint-free cloth

C. A damp sponge

D. A dripping wet cloth

10. To remove dust from inside a laptop, which of the options should the technician use? (Select two answers.)

A. Use alcohol swabs.

B. Use compressed air.

C. Gently blow the dust out.

D. Vacuum the dust out of the system with a special antistatic vacuum cleaner.

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The Ultimate Computer Repair Guide

The Ultimate Computer Repair Guide

Read how to maintain and repair any desktop and laptop computer. This Ebook has articles with photos and videos that show detailed step by step pc repair and maintenance procedures. There are many links to online videos that explain how you can build, maintain, speed up, clean, and repair your computer yourself. Put the money that you were going to pay the PC Tech in your own pocket.

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  • Girmay
    What can cause a brownout cisco IT essentials?
    3 years ago
  • Tom
    What should you do with sleeves and neckties when working with electronic components?
    3 years ago
  • idris alem
    What are the four esd protection recommendations for preventing esd?
    2 years ago
  • donna
    How many volts must be built up before you feel the ESD?
    1 year ago
  • christian herz
    How to clean contacts on a pci expansion card?
    1 year ago
  • Filibert Galbassi
    Why should the metal on the back of the wrist strap remain in contact with the skin at all times?
    1 year ago

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