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Cisco Chapter 2


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complete loss of AC

 Caused by:

  •  Blown fuse
  • damaged transformer
  • downed power line 

Reduced voltage level of AC

Occurs when:

  • line voltage drops below 80%
  • overloading  

Interferance (unclean power)





Short spike in voltage exceeds 100% normal


Power comes back on

lighting strike


Power Surge  

Dramatic increase in voltage above the normal flow of electrical current. 


Can last a few nanoseconds or one billionith of a second 

Power Protection Devices
Protect against power fluctuations
Surge Suppressor  

Protects against surges or spikes.  

 Diverts extra voltage to ground

Uninterruptible Power supply
What don't you do with a power supply or CRT?
use a static strap

Fire Extinguisher Classifications

Ordinary Combustible

  • Paper
  • Wood
  • plastics
  • cardboard 

Fire Extinguisher Classifications

Flammable Liquids

  • Gasoline
  • Kerosene
  • Organic solvents


Fire Extinguisher Classifications

Electrical Equipment


Fire Extinguisher Classifications

Combustible Metals

P - Pull the pin

A - Aim at the base of the fire not at the flames

S - Squeeze the lever

S - Sweep the nozzle from side to side 

How many volts must build up before it is felt?
How many volts to cause pain or make noise
How many volts will damage computer equipment?
Uninterruptible power supply (UPS)
Provides electrical power to computer or device
What does a UPS do when power is lost     
It is constantly recharging while the UPS is in use.  Supplies quality power during brownouts and and blackouts.
What does the UPS do with the OS?
Allows UPS to safely shutdown the computer
Standby Power Supply
Standby Power Supply (SPS)

helps protect against voltage drops below normal level. 

 Other things:

  • The battery provides DC power to a power inverter, which converts it to AC power for the computer. 
What makes the Standby Power Supply (SPS) not as reliable as the UPS
  • Because of the time it takes to switch over to the battery.
  • If the switching device fails, the battery will not be able to supply power to the computer. 
What is the hazardous materials of the computer called?
Toxic Waste
Material Safety and data sheet
What is a msds

summarizes information about material identification including:

 hazardous ingredients that can affect personal health

fire hazards

first aid requirements

chemical reactivity and incompatibility

spill leak and disposa

How do you determine if a material is classified hazardous?
Contact Occupational Safety and Health Administration (OSHA)
Occupational Safety and Health Administration
What does OSHA require
All hazardous materials must be accompanied by a MSDS when transferred to a new owner
Chemicals Hazard Information and Packaging
What does Chip3 require
chemical suppliers to safely package and transport dangerous chemicals and to include a data sheet with the product. 
What does MSDS contain
  • The name of the material
  • The physical properties of the material
  • Any hazardous ingredients contained in the material
  • Reactivity data, such as fire and explosion data
  • Procedures for spills or leaks
  • Spec
What are the reasons computers are discarded?
  • Parts or components begin to fail more frequently as the device ages.
  • The computer becomes obsolete for the application for which it was originally intended.
Newer models have improved features.
What rare earth metals to batteries contain?

Batteries from portable computer systems may contain:l


  • lead
  • cadmium
  • lithium
  • alkaline manganese
  • mercury 
Envirnmental protection agency
CRTs may contain 4lbs of what?
what should you do when disposing of solvents and aerosols 
contact local sanitation company
What are the 2 ESD tools?
  • Anti static wrist strap
  • Anti static mat 
What does a static mat do?
protects computer equipment by preventing static electricity from accumulating on the hardware or technician.
What are 2 diagnostic tools used on computers?
  • digital multimeter
  • loopback adaptor 
What type of hand tools are used on computers?
small hand tools
Disk managment tools

help detect and correct disk errors

prepare a disk for data storage

remove unwanted files 

fdisk or disk management
creates or deletes partitions of HD
Prepares HD to store information
Scandisk or CHKDSK
checks integrity of files and folders by scanning surface of the disk for physical errors
Optimizes space on HD
Disk Cleanup
Clears Space by searching for files that can be safely deleted
Disk Managemnet

a system utility used to manage HDs and partitions


  • initializing disks
  • creating partitions
  • formatting partitions 
System file checker
SFC does what
command line tool that scans the OS critical files and replaced the corrupted ones
Windows XP Boot Disk

Repairs corrupted files

windows system files

restore damaged or lost

reinstall the OS


Third party software is also avialable that does the same thing 

Windows XP Security Center

Checks all security settings

Continously checks to make sure the firewall and antivirus are running

automatic updates 

Protects against unauterized communications
Personal reference tools include

troubleshooting guides

manufacturer manuals

quick ref guides

repair journal


Internet reference tools
  • Internet search engines
  • News groups
  • Manufacturer FAQs
  • Online computer manuals
  • Online forums and chat
  • Technical websites
What should you do before repairing equipment?

Make sure tools are in good condition




Anything that isn't in good working condition 

What does an antistatic strap do?

equalize the charge between you and the equipment

A conductor that connects your body to the equipment that you are working on.


What type of clothing shouldn't you wear when working on computers?




when working at a workbench what should you do?
ground the workbench and the antistatic floor mat. 
six sided
Should you use magnatized tools on a compute?
Why shouldn't you use pencils for dip switches etc?
Pencil lead can act as a conductor and may damage computer components.
What should you do before cleaning any device?
Turn it off and unplug
what does dust do to computer components
acts as an insulator and traps heat
What should you use to clean a computer case and monitor?

damp lint free cloth

one drop of dishwashing liquid with four ounces of water 

Cleaning LCD Screens
Do not use ammoniated glass cleaners unless specifically designed for lcds
What should be used to clean component contacts

isopropl alchohol.  Do not use rubbing alcohol.


Blow off with compressed air to remove any remnents of lint from q tip 

What should you use to clean a mouse
glass cleaner and soft cloth
How do you clean a heatsink
compressed air
how do you clean a keyboard
hand held vacuum with brush attachment

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