chapter 2 safety

Known good spares

are a set of components that you know are in proper functioning order. If you suspect a problem in a component, swap it with the known good component. If the problem is not resolved, troubleshoot other components. Examples of using this strategy are: Changing the cable connecting a computer to the network Connecting a different monitor to a computer Replacing an expansion card

MSDS

describes safe handling and disposal procedures for dangerous materials and can provide you with the knowledge to resolve an uncertain situation.

Test the solution

-When you are testing your solution, do the following: -Ensure that the problem is fully resolved and that implementation did not cause any new problems. -If necessary, take additional actions to prevent the problem from happening again.

Surge suppressor

A device that conditions under-voltages and over-voltages before they reach devices and damage them.

Line conditioner

A device that modifies power signals to remove noise and create a smooth AC electrical signal

Surge protector

A device that protects systems from under-voltages by switching the system off

Uninterruptible power supply (UPS)

A device that provides battery power to a computer in case of an under-voltage.

Line Conditioner

A line conditioner modifies the power signal to remove noise and create a smooth alternating current (AC) signal.

Electromagnetic interference (EMI)

A signal caused by motors, heavy machinery, and fluorescent lights that interferes with wired networking signals.

Standby Power Supply (SPS)

A standby power supply is an offline device that switches over to provide power when an undervoltage occurs. If the switchover is not fast enough, the computer loses power.

Surge Protector

A surge protector protects against overvoltages by switching a device off before an overvoltage can damage it. A power strip provides multiple power outlets from a single plug-in, but is not necessarily a surge protector. Surge protectors can be destroyed by surges and lose their ability to protect. Consider using a surge protector with an indicator light to show whether it is working correctly.

Surge Suppressor

A surge suppressor conditions power so that overvoltages don't reach devices.

Ensure satisfaction

After the problem is fixed, ensure the customer's satisfaction and explain what you did to fix the problem. If possible, have the user perform the task to make sure that they understand and accept that the problem has been resolved.

Standby power supply (SPS)

An offline devices that provides power when an under-voltage occurs.

Spike

An over-voltage that lasts milliseconds.

Surge

An over-voltage that lasts seconds

Sag

An under-voltage that lasts milliseconds.

Brownout

An under-voltage that lasts seconds.

Uninterruptible Power Supply (UPS)

An uninterruptible power supply is an online device that is constantly providing battery power to the computer and being recharged by the wall outlet. There are two types of UPS systems: An online UPS constantly powers the computer from the battery. An offline UPS powers the computer from the wall power. When the power fails, a switch inside the UPS switches to power the computer from the battery. This is the most common form of UPS. UPS size is measured by the volt-amp (VA) rating. The capacity of the UPS determines the number of devices and how long the devices can run when power is interrupted. When purchasing a UPS, purchase one with enough battery power to power only critical devices such as the computer and a single monitor. To reduce the amount of power required by the UPS, do not plug non-critical devices in to the UPS. Laser printers require more power than most UPS systems are capable of providing. For this reason, you should not connect a laser printer to a UPS. If you must provide power to a laser printer, get a dedicated UPS for that device. A UPS is designed to provide enough power to shut a system down safely during an extended power outage. Most are not intended as long-term power solutions. The UPS connects to the power source (usually a wall socket), the computer plugs into the UPS, and the UPS is connected through a serial or USB port to the computer. Software on the computer uses this connection to monitor battery life and to detect when the regular power is lost. You can configure the software to shut the system down automatically when the battery charge reaches a certain level. You usually need to configure the following settings when working with UPS software: Time to wait before sending a warning to clients Time to wait before beginning a shutdown Name of programs or commands to run during shutdown ------------------------------------------ In addition to providing power when the power is lost, most UPS systems also condition the line and remove power spikes and sags. Most UPS devices sound an alarm when the AC power is lost. This alarm continues until AC power is restored, although many UPS devices have a switch to mute the alarm.

Lifting

Be careful when lifting heavy objects. Bend your knees and keep your back straight, using your legs to lift objects. If your job requires frequently lifting, wear a back brace for added protection. Use carts and other tools when moving heavy objects for any significant distance. If necessary, ask for help when lifting or moving heavier objects. Follow the weight limitation guidelines defined by your employer.

Capacitor

Be sure to discharge capacitors or turn the equipment over to qualified personnel for servicing. Similarly, exercise caution when working with the DC converter in a laptop display

Back up the system

Before making changes to the system, back up user and system data (or make sure a recent backup exists). While some changes can be made without affecting user data, you should back up data to protect against unintentional data loss caused by making changes.

Identify possible causes and identify a theory of probable cause

Check for simple, obvious, and common problems first. For example, check power cords, connectors, and common user errors.

Blackout

Complete power failure

Blackout

Complete power failure.

Thermal

Components such as the CPU heat sink and fan, the printing head of a dot matrix printer, or components inside a laser printer can be hot. After turning off a computer, allow components to cool sufficiently before servicing to prevent burns.

Cleaning solutions and solvents

Consult the MSDS, a licensed disposal organization, or local authorities for handling and authorized disposal procedures.

CRT Monitor

Contact local authorities for recycling these. CRTs contain many toxic and caustic substances that are illegal to incinerate. Also, discharge before disposal (CRTs can contain high voltages).

Power Supply

Contact local authorities. Recycle, if possible. Discharge before disposal (contains high voltages). ac to DC voltage.

Scope

Define exactly what you wish to change and, if helpful, what you don't wish to change

Component or Material

Disposal Method

Document the solution and process

Documenting the solution and process provides you with a record of what the problem was and what you did to solve the problem. In the future, you can check your documentation to see what has changed or to help you remember the solution to common problems. It will save you time and money when troubleshooting problems.

Electromagnetic Interference (EMI)

EMI is interference that affects wired networking signals. EMI is caused by motors, heavy machinery, and fluorescent lights. Use shielded twisted pair cable to protect signals sent on Ethernet twisted pair cabling. If necessary, use fiber optic cables to eliminate the effects of interference.

Fire

Every room in which you work should be fire suppressed. At a minimum, you should have a Class C fire extinguisher available to you. A Class C fire extinguisher is made for electrical fires. Make sure fire extinguishers and fire suppression methods (e.g., sprinklers) are properly implemented and maintained. Promptly report any potentially hazardous situations. Your top priority in responding to any incident is to ensure the safety of others. In the event of a hazardous situation, clear people from the area or remove the danger before attempting other actions such as preventing or repairing damage to components.

ESD and High Voltage

Exercise great care when working with electricity. ESD wrist straps not only protect components, but can reduce the chance of accidental electrical shock. Properly ground yourself before working with components. Do not use an ESD wrist strap when working with monitors, power supplies, laptop LCD panels, or other high-voltage components. You should be especially careful when wearing jewelry, because it readily conducts electricity and could cause burns or even electrocution.

Heating, Ventilation, and Air Conditioning (HVAC)

For computer components, design HVAC systems with the following in mind: Keep temperature between 70 and 74 degrees to prevent components from overheating. Keep humidity between 40 and 70 percent to prevent electrostatic discharge (ESD). Make sure server rooms have separate ducting or HVAC systems from the rest of the building for better temperature control. Use positive pressure systems. Positive pressure systems protect the air quality in the facility by causing air to be forced out through doors, windows, and other openings. Negative pressure systems draw air in, potentially bringing in airborne particles such as dust or smoke. Positive pressure systems are more energy effective. In areas with heavy smoke or dust, add filters to air intake systems to filter out airborne particulates.

Risk Analysis

Identify risks associated with the change. For example, allocating additional funding to the project may strain another project's budget. Adding a new member to a team may negatively impact the team's effectiveness as training the new member will cause stress and consume time. Explain why the risks you identify are worth taking, and present a plan for mitigating risks and avoiding problems.

Approval Process

If the change board approves your change request, then the change is proposed to the end user, usually a customer, for approval. Ensure that you receive written approval from all necessary parties to protect yourself and others from misunderstandings and their expensive and destructive effects. Once all parties approve a change, all of the documents associated with a project must be updated to reflect the change, including the project plan, budget, allocated resource documentation, and any other projects the change affects.

Interference

Interference is a signal that corrupts or destroys regular signals. Interference affects signals used by two devices to communicate on a network. Listed below are two types of interference that affect computer networks:

Troubleshooting Tips

Keep in mind the following tips when troubleshooting systems: -Often the hardest part of troubleshooting is to reproduce the problem. You might need to ask the user questions to identify exactly how the problem occurred, or you might need to watch them perform the task again to reproduce the problem. -If a hardware device or a software program causes a specific error, check the manufacturer's website for additional help in troubleshooting the error. To help diagnose issues, you can run special software tools supplied by the hardware manufacturer. -In addition to a basic toolkit, you can keep a few spare parts on hand that you know to be in working order. If you suspect that a component has failed, replace it with the known good spare. If that solves the problem, replace the faulty component. -Intermittent problems are particularly difficult to troubleshoot. Check for environmental conditions such as kinked cables or overheated components. -If you have problems identifying a hardware error, you can simplify the system by removing all but necessary components (processor, memory, and hard disk). Add devices one at a time and restart the system. If an error occurs, remove the newly added device and troubleshoot that device. Another strategy would be to remove a single device and restart the system, seeing if removing that device corrects the problem. -Some problems might be caused by software errors, not hardware failures. You might need to begin by updating the drivers or unloading software. -Before you make changes, always consider corporate policies and procedures and the changes' impact on other people and components.

Magnetic Fields

Magnetic fields located close to a computer can cause undesired effects or even data loss. Hard drives use magnetic charges to store data. While hard disks are shielded and protected from all but the strongest magnets, getting a magnet too close to these components could erase data. Speakers, motors, and generators contain magnets (keep sensitive components away from these devices). Solid state storage devices (such as RAM or flash drives) are not affected by magnetic fields.

Physical

Make sure the room and the building are properly set up to ensure your safety. Keep work areas and floors clear of clutter to help prevent accidents. Do not route cables across the floor in pathways. This can lead to tripping accidents, and could also result in worn cables. Provide adequate ventilation in any enclosure to remove toxic fumes. Protect yourself from airborne particles by using an air filter mask. Wear safety goggles. Replace worn or frayed power cords.

Spike

Overvoltage that lasts milliseconds

Surge

Overvoltage that lasts seconds

Peripherals

Peripherals can present a safety hazard to you. Do not use a regular multimeter or other electrical testing equipment to measure charge inside a monitor. Never clean the monitor's glass with a liquid solvent while the monitor is powered on. Some studies suggest that laser printers emit tiny particles which could be dangerous when inhaled. As a precaution, do not locate laser printers immediately next to desks, and keep the area ventilated. Avoid handling leaky batteries. The leaking electrolytes can be harmful if they get into your eyes. Never look into the end of a fiber optic networking cable. Laser light can damage your eyes.

Power

Power hazards can cause electrical shock and burns. Before handling a system component, make sure that it is powered off and that the main power cord is unplugged from the wall socket. Ensure that the grounding pin on a PC power plug is intact. Because newer power supplies constantly pull power from the socket, unplug the system before working on internal components. The power inverter (power supply) converts AC current to DC current. The power supply can retain an electrical charge, even when not plugged in. Replace faulty power supplies instead of trying to repair them. Avoid opening the power supply which houses a capacitor (stores a large charge of electricity).

Backout Plan

Present a plan for returning affected systems to their original state if your proposed change to a hardware or software implementation fails.

Plan

Provide a plan for implementing the change. This plan may include extending the project schedule, requesting additional resources, requesting additional funding, and any other impacts to the project.

Purpose

Provide an explanation about why you wish to make this change to the project.

Radio Frequency Interference (RFI)

RFI is interference on the radio channel used by wireless networking devices. RFI can be caused by nearby wireless devices using the same channel, cordless phones, or microwave ovens. Wireless networks that use the 2.4 GHz frequency range (801.11b and 802.11g) are susceptible to RFI. You can reduce RFI by using a wireless networking standard that operates in the 5.75 GHz range or using a different channel for wireless devices.

Nickel Metal Hydride (NiMH) Batteries

Recycle these; NiMH batteries are considered a non-hazardous waste in most U.S. States, with the exception of California.

Lithium and Lithium Ion Batteries

Recycle these; lithium batteries are considered a non-hazardous waste.

PC System

Recycle, give it away, or resell it; a typical PC contains $5 to $25 worth of precious metals. Remember to clean the hard drive before disposing of the machine.

Alkaline Batteries

Recycle, if possible, otherwise dispose of alkaline batteries as your local laws require. For example, in some states, you can throw them in the regular trash. In California, it is illegal to throw them in the common trash. They are considered hazardous waste and are supposed to go with the household hazardous waste collection for special recycling.

Inkjet Printer Cartridges

Recycle; you can return the cartridges to the manufacturer for recycling or recycle them yourself

Laser Printer Toner Cartridges

Return to the manufacturer for recycling (to clean up spills, use a toner vacuum or a scoop and a damp cloth; never use a regular vacuum).

Radio frequency interference (RFI)

Signals caused by cordless phones, microwave ovens, and wireless devices that interfere with wireless networking.

Test your theory

Test your theory to verify the cause of the problem. -If your theory is not correct, examine other possible causes (return to the previous step). -At this point, if the problem is caused by simple things like an unplugged system, you can safely take actions to resolve the problem. -If the cause is not a simple one, identify the necessary steps to correct the problem. -If you cannot identify the cause of the problem, or if the problem is beyond your ability or responsibility to fix, escalate the problem.Escalation means turning the problem over to someone more capable of handling the problem. When escalating the problem, be sure to detail the actions you took and the information you have discovered up to this point.

Heating, ventilation, and air conditioning (HVAC)

The system installed within buildings to control temperature by supplying heat and air conditioning.

Button Batteries

These are considered hazardous waste because they contain mercuric oxide, lithium, silver oxide or zinc-air. Return to manufacturer, recycle, or contact local authorities for disposal procedures

Nickel-Cadmium (NiCad) Batteries

These are considered hazardous waste; take these batteries to either a household hazardous waste site or a recycling center.

Create an action plan

To create an action plan, address the most likely problem and account for side effects of the proposed plan. For example, -Will the fix result in significant system downtime? -Is the resolution best left for other times of the day? -Is there a temporary solution that should be implemented immediately? When side effects have been weighed against the fix and all concerns have been addressed, fix the problem.

Sag

Undervoltage that lasts milliseconds

Brownout

Undervoltage that lasts seconds (lights dim)

Identify the problem

When identifying the problem, resist the urge to start fixing things at this point. To identify the problem: -Ask the user to describe the problem, check for error messages, or recreate the problem. -Establish what has changed. Most often, problems are caused by new hardware, software, or changes to the configuration. If necessary, carefully ask users to discover what might have changed that could have caused the problem. Remember to inquire about environmental and infrastructure changes that could be relevant. -Review system and application logs. -Check knowledge base articles, network topology diagrams, and any other documents that may provide helpful information.

Combination ratchet/screwdriver

has interchangeable bits with a ratcheting handle that provides multiple features in a single tool. Bit ends can be replaced for Phillips and flat-head screwdrivers, hex sockets, and torx (star-shaped) bits. The ratcheting handle allows you to drive the screw without repositioning the driver. Most computer components use Phillips head screws

Toner Probe

includes two components. One component creates a tone, and the second component has a speaker to hear the tone. This is used to trace network cables between two different locations. For example, if you have 50 cables going from an office to a wiring closet, you sometimes need to identify both ends of the same cable. You can connect the component that creates the tone to one end of the wire in the office. Next, you go to the wiring closet and begin touching the speaker to different wires. When you hear the tone, you have found the wire.

power supply tester

is a custom multimeter that is used for testing output from a PC power supply. The power supply tester has multiple connectors to test the output for each connector type

Multimeter

is a device for testing various electrical properties. For example, most multimeters can measure: AC and DC voltage Current (amps) Resistance (ohms) Capacitance Frequency Multimeters include two probes and are used to measure voltage, amperage, and resistance. These are commonly used to measure voltages from power supplies but have a different use with networks. True or false? Multimeters are commonly used to measure amperage going through network cables. Answer: False. Multimeters are rarely used to measure amperage (or current) through network cables. Most multimeters include a continuity checker that can be used to verify that a cable doesn't have any breaks. This setting measures when a cable has zero resistance or is continuous from end to end. When you select the continuity check function and touch both probes together, the multimeter beeps, indicating that there is a continuous connection. Similarly, when you touch both ends of a cable with each of the probes, it beeps if the cable is good. If you don't hear a beep, you know the cable has a break.

Extension magnet

is a small magnet on a collapsible rod. Use the extension magnet to retrieve screws that have fallen into a computer case or other areas you cannot reach. As an alternative to a magnet, use an extension tool with retractable prongs.

POST card

is an expansion board that you insert into an expansion slot. It is typically used to troubleshoot a computer system that doesn't start up correctly. This car displays output from the BIOS during the Power-On Self-Test (POST).

IC insertion and extraction tool

is used to add or remove integrated circuit chips that are used on motherboard and some computer components. For example, on some motherboards you can use the IC insertion and extraction tool to change the BIOS chip.

3-pronged parts retriever

is used to grasp and retrieve small parts that have fallen into difficult to reach areas.

loopback plug

is used to test network communications by redirecting a signal from the transmit port on a device to the receive port on the same device. Use the loopback plug to verify that a device can both send and receive signals

Antistatic pad/wrist strap

provides an insulated covering to prevent static electricity from moving between objects and damaging computer components. When working with computer components, use a wrist strap connected to the antistatic pad, and connect the pad to a ground.

cable tester

verifies that a network can carry a signal from one end to the other, and that all wires within the connector are in their correct positions. Most testers have a single unit that tests both ends of the cable at once. Many testers come with a second unit that you can plug into one end of a long cable run to test the entire cable. often used with twisted-pair cables. They have RJ-45 ports where you connect the cable. The cable tester first verifies the wiring and then verifies that the cable meets operational characteristics. For example, a cable tester can verify that a CAT 6 cable can transmit data at a rate of 10 Gbps using a frequency of 250 MHz.