Read an Excerpt
Chapter 3.An Ounce of Prevention...
- Preventative Maintenance Products
- Liquid Cleaning Compounds
- Cleaning Contacts and Connectors
- Non-Static Vacuums
- Compressed Air
- Working with Power
- Uninterruptible Power Supplies
- Surge Suppressors
- Storing Components for the Future
- Handling High-Voltage Equipment…or Not
- Disposing of the Junk
- Monitors (CRTs)
- Toner Kits/Cartridges
- Chemical Solvents and Cans
- Electrostatic DischargeEnemy Number 1
- What Is ESD?
- Hidden ESD
- ESD Protection Devices
- Key Points
- Chapter Review Questions
Chapter 3 An Ounce of Prevention...
Somebody much wiser than us once said that an ounce of prevention is worth a pound of cure. This is certainly true in the world of computers. Pound of cure aside, PC preventative maintenance is a little like eating healthywe know it’s a good thing but when no one is looking we put away the tofu and bran and find the nearest drive-thru. At the end of the day, seasoned computer technicians are well aware that a few moments spent cleaning, inspecting, and caring for computers can prevent hours spent replacing, troubleshooting, and repairing them. In fact, regular cleaning of our computer and peripherals will prolong the life of both.
Domain 3.0 of the CompTIA A+ objectives focuses on the products and procedures that we, as PC technicians, use as part of our preventative maintenance regimen. In addition, the objectives within this domain include topics on PC safety, including a discussion of the potential hazards when working with computer components such as lasers and high-voltage equipment. Both of these objective areas are addressed in this chapter.
Walk into any grocery store today and you will be able to locate rows of shelf space dedicated to cleaning products and supplies. Some of these cleaning products are abrasive, some smell like lemon, and others claim to soften your hands while you scrub. Of the myriad products out there, which ones do we use to clean our computers? Do we need softer hands?
Some of these cleaners are obviously wrong for our needs. For example, we are unlikely to use silver polish to clean an LCD screen but would we use regular window cleaner? What’s the best for getting bacon bits out of the keyboard or greasy fingerprints off a monitor? In this section we answer these questions and identify the products to use for cleaning computer components and even provide a little personal insight gleaned from a few mistakes we’ve made over the years.
Mean Time Between Failures
You might hear someone refer to the fact that preventative maintenance can increase mean time between failures (MTBF). This well-used acronym is used to describe the average time a component is expected to work without failing. Finding the actual MTBF for some components such as keyboards and mice is difficult as they typically run for a long time. Other components such as hard disks, which comparatively speaking fail frequently, have published MTBF times so that you can use this information in your purchasing decisions.
Whether preventative maintenance really increases MTBF is a source of some debate. Some would say that preventative maintenance simply allows you to realize a product’s full MTBF. Others would say that it extends it. Either way, for a given device there is no way to really know if your preventative maintenance steps make a difference.
Most of us are aware that computer systems and associated peripherals are sensitive devices; they do not like a lot of water and most cleaning products available. So what can we use?
Water and a Damp Cloth
In the high-tech world, one of the most often used cleaning supplies is the very nontechnical soapy water and lint-free damp cloth. Considering that the exterior of most computers and peripherals is plastic or metal, a damp cloth and a little soapy water are just great for cleaning these surfaces. There are a few caveats here, however. The cloth must only be damp and not wet. The last thing you want to do is spill drops of water onto the actual components of the system. Before wiping down the outside of components, you need to unplug them. Water and electricity don’t mix. Finally, the water and damp cloth solution is for cleaning the exteriors of devices only, not the internal components. There are better "solutions" for those.
Denatured (Isopropyl) Alcohol
For cleaning the inside of some components such as floppy drives, or more specifically floppy drive heads, we can use a little alcohol. The cleaning solution is typically applied with a lint-free swab directly to the heads. When we say lint-free swab, we don’t mean a regular cotton swab, as often the cotton itself can jam up the very components we are trying to clean.
Even with denatured alcohol moderation is the key. You will find that when cleaning components, you only need a little alcohol on the swab. One caveat with alcohol is to not clean moving parts within components that use lubricants, such as the gears and drive motors in CD-ROMs, floppy drives, and printers. For many of these, the alcohol will clean off the lubricants that need to be there.
Regular Glass Cleaner
One of the first impulses when cleaning some computer components is to reach for the glass cleaner. In truth, glass cleaner has limited application for cleaning computer equipment. Its use should be restricted to cleaning the display screen of a CRT monitor. Glass cleaner should never be used to clean an LCD screen; it can eat right through it!
Regular glass cleaner should never be used to clean LCD displays.
In terms of liquid cleaners, water, denatured alcohol, and glass cleaner are all you will really need. The trick then is deciding which of these cleaners to use with which component. To give you some idea, we will look at some common computer components and peripherals and what it takes to clean them.
It is a best practice to make sure the computer component or peripheral device you are cleaning is unplugged before cleaning. This includes everything from mice to monitors and keyboards.
- Mouse The average mouse is a virtual playground for all manner of germs and bacteria. The outside of the mouse can often be cleaned using a little elbow grease and a damp and soapy cloth. On the inside, some people recommend using an eraser to clean the mouse ball. This is a double-edged sword; it can clean the ball but it has an abrasive effect and can cause small canyons on the surface of the ball and change its shape. As you can imagine, this affects the proper functioning of the mouse. A better solution is to once again use a damp cloth to wipe off the mouse ball. This should be enough to get it clean and smooth off the surface. Do not soak the mouse ball, and make sure it is dry before putting it back in its home. To clean the inside of the mouse, we would not suggest using any liquid cleaners. If the rollers on the inside are dirty, the dirt on them can be gently scraped off. In addition, a can of compressed air can be used to blow out the dust and dirt. Regular maintenance on mice can greatly prolong their life but if you find yourself working in an environment where you are supporting hundreds of computers, this can be a time-consuming task. Given the relatively low cost of mice, in some cases it might be easier just to replace the mouse with a new one if it starts giving you trouble.
- Keyboard The keyboard probably needs to be cleaned more than any other computer component. Most experts (if there is such a thing as a keyboard cleaning expert) suggest using distilled water to clean the surface areas of the keyboard. Using only distilled water is an important consideration as any soap or iron in the regular water can cause as many problems as it cures. We have seen some people completely soak their keyboards in distilled water and have them function normally afterward. Such an approach might work well on older, $20 keyboards, but the newer, more advanced, and more expensive keyboards require a bit more TLC. The underside of the keys can often be cleaned using just a can of compressed air. You will be surprised by what comes flying out from underneath those keys. The keyboard’s surface areas typically require little more than a damp, lint-free cloth using a little distilled water. Some spills such as coffee or other liquids might require that you remove keys to get underneath them to clean. Spills such as cola, which can leave your keys sticky and nonfunctioning, might require that the keyboard be soaked in distilled water, which is OK because at this point you really do not have anything to lose. The best preventative advice we can offer on preventing spills is simply to never drink liquids around the keyboard. One important thing to remember when cleaning a keyboard is to ensure that it is completely dry before reconnecting it to the computer. This can sometimes take more than 48 hours.
- Monitor If keyboards are the device we clean the most, monitors have to be a close second. Most often the display screen is simply dusty and all that is needed is to wipe the display with a lint-free cloth. For stains or spills, the best way to go is regular glass cleaner, provided, as we mentioned earlier, that it is not being used on an LCD screen. If you are using a spray cleaner, it’s best not to spray the cleaner directly on to the monitor. Instead, first squirt it onto a lint-free cloth and then use that. To make things a little easier, you can also purchase presoaked antistatic cleaners that resemble little towelettes. These do a great job of removing the dust from the display. The outside of the monitor can be cleaned using a damp cloth and the vents can be cleaned using some compressed air. As mentioned earlier, to prevent water from getting inside the vents, do not use a cloth that is too wet. Again, the monitor must be unplugged before any cleaning can take place.
- LCD monitor The first rule of thumb is to never allow any moisture to get into your LCD monitor. If you notice moisture on your screen, wipe it off gently with a soft cloth before powering on your monitor. If for some reason moisture has managed to get into the LCD monitor, leave the monitor in a warm area until the water has had a chance to evaporate. As with CRT monitors, LCD screens are often as easy to clean as wiping them with a lint-free cloth. If you do need to rub off a stain or other such blemish, you can use a small amount of distilled water on a lint-free cloth and wipe the stain, but only when the LCD screen is completely off. Do not apply too much pressure to the screendoing so can damage the interior of the panel.
- Floppy drive Floppy drives can quickly get full of dust, and over time this will cause them to fail or at the least not function as they should. The trick for floppy drives is a little denatured alcohol on a swab to clean the floppy drive heads. To remove the dust from inside a floppy drive, you might have to use a non-static vacuum (discussed later in this chapter) or a few shots of compressed air. Like some of the other components discussed here, if the floppy drive refuses to work even after a cleaning, it might actually be more economical (though not as environmentally friendly) to replace the floppy drive with a new one.
When cleaning keyboards, ensure that they are first disconnected from the computer and completely dry before using them again.
Do not clean the monitor while it is plugged in! Be sure the monitor is disconnected from the PC and unplugged from the electrical outlet before cleaning.
If you power up an LCD monitor with moisture in it, the electrodes can become corroded, leading to permanent damage.
The computer itself is full of contacts and connectors that must be clean in order to function as they should. If dirt or grime gets on these connectors it can prevent a proper connection between devices, or the dust itself can cause electrostatic discharge (ESD). To be clear, the types of connectors and contacts we are talking about are those found on components such as expansion cards and memory modules.
There is a more detailed discussion of ESD later in this chapter.
If you ask around, you are certainly going to receive a number of different ideas for cleaning contacts and connectors. Some of these are valid, some are actually more damaging than leaving the dust on the connectors. The most accepted method of effectively cleaning contacts is to use a lint-free swab to rub a little denatured alcohol on the contact. This will certainly remove any dust and dirt and ensure that clean contact is made. If you are having periodic trouble with an expansion card or memory module, it might be worth your time to clean the contacts and see if the problem is resolved.
One of the more common methods used to clean contacts is to use an ordinary eraser. Erasers have been used to clean contacts as far back as we can remember and actually do a very poor job of it. The problem with erasers is that they often leave more residue than they remove, and the ever popular pink erasers have chemicals in them that can actually harm the contacts. If you are convinced that erasers are the way to go for cleaning contacts, ensure that you use a white eraser as it is less likely to cause damage than a pink one. Personally, we would recommend avoiding erasers and sticking with the denatured alcohol or specialized contact cleaning solutions, which can be purchased from electrical supply stores.
One final technique we should mention is using emery cloth, which is essentially a very fine sandpaper, not unlike the type used to file your fingernails. This can be used effectively to clean contacts and connectors. Care must be taken not to run the cloth over the circuit board itself, as this can damage it. Also, if you are using emery cloth, be sure to do only one or two strokes. Any more might actually start to erode the contacts.
As mentioned earlier, dust is an enemy to computer systems. One of the tools you are likely to see used in the war against dust is a non-static vacuum. Non-static vacuums are seen in most PC repair shops and are used for sucking the dust out of the computer case, keyboard, power supplies, and even peripheral devices (not to mention the crumbs from lunch!). However, before running to the closet and grabbing the Electrolux, it should be pointed out that non-static vacuums are specifically designed for use with computers. Regular vacuums actually create a storm of static electricity and can damage the components you are trying to clean. Save those for the carpets.
For those who are not fond of vacuuming, there is another method you can use to remove the dust from inside the computer case and peripheralscompressed air. Compressed air is sold in cans and, as a computer technician, having one or two cans in your toolkit is a definite must. The compressed air is well suited for cleaning fans, power supplies, and those hard-to-reach places. The biggest drawback with compressed air is that the dust is blown everywhere. The best method is to use compressed air on the outside of a device. Some technicians prefer to use their own compressed air by blowing on components. While this is not a terribly bad thing, human breath is moisture laden and so not ideal for this purpose.
Part of the role of the PC technician is to be aware of the environmental factors that might affect the functioning of a computer system. One of the more important environmental factors to be aware of is power. Several power conditions can cause problems. The most common of these include
- Sag A drop in power supply that only lasts a short period, a sag is generally the most common type of power anomaly.
- Brownout A brownout is a drop in supply voltage that lasts more than a few seconds.
- Spike A spike is a sharp and very sudden increase in line voltage that pushes the supply voltage above an acceptable threshold.
- Surge A surge is an unacceptably large increase in supply voltage that lasts longer than a spike. This condition is also known as a swell.
- Noise Noise is interference can cause the supply voltage to be inconsistent.
- Blackout A blackout is a complete failure in power supply.
Before taking the A+ exam, ensure that you are familiar with the power conditions in the preceding list.
Any of the power threats in the previous list can cause a loss of data and even damage the computer equipment. Your role as a PC technician then becomes protecting computer systems from these threats. To do this we commonly use two types of devices, uninterruptible power supplies (UPS) and surge suppressors.
Power-related problems are the single highest cause of data loss, an estimated 10 to 15 percent higher than computer viruses.
Part of the planning for potential power hazards will often include the installation of a UPS system. Our reliance on computer systems has meant that we must protect against all possible interruptions in service, and power is no exception. UPSs provide protection against fluctuations and loss in power, thereby allowing equipment to continue running.
What Is a UPS?
At its most basic, a UPS is simply a box that holds a battery, a built-in charging circuit, and an inverter. Its function is to power the computer in case of a power outage, and to provide sufficient time to allow a computer user to properly shut the system down and prevent data loss. Figure 3-1 shows a UPS in action.
Figure 3-1 A standard UPS system protects your equipment. (Image unavailable)
An inverter is a piece of electrical equipment that converts power from one format to another. In the case of UPS systems, the inverter is used to convert the power from the battery, which is DC power, into AC power, which is used by the connected equipment.
When the power supply is good, the battery is charged. When the power fails or does not meet requirements, the battery supplies power to the equipment connected to the UPS.
This description is true of an offline UPS, and though the UPS’s function of supplying power to the computer might sound simple enough, today’s UPS systems are far from simple devices. As well as providing protection from actual power outages, modern UPS systems come equipped with a host of other features as well as a variety of methods of monitoring power activity.
To ensure that connected equipment is not affected by a loss of power, offline UPS systems are designed to make the transfer between standard power and battery power very quickly. The actual interval is usually measured in milliseconds and is known as the transfer time. The power supplies of equipment connected to the UPS are sufficiently insensitive to not notice this very tiny interruption in power and so continue operating uninterrupted.
In contrast to offline UPS systems, today it is far more common to find online UPS systems with intelligent management features. Online UPS systems are more suited to use with sensitive equipment as they always supply power to connected equipment through the batteries. This provides two benefits. First, it means that in the case of a power failure, there is no transfer from main power to the UPS battery, eliminating the slim possibility that the connected equipment might not detect the switch or, even less likely, that the UPS might fail to switch over correctly. Second, the constant supply of power from the batteries in online UPS systems makes it is very easy to condition and regulate the power.
Smart or Dumb?
UPS systems are sometimes referred to as being smart or intelligent. That does not mean they are able to balance your checkbook; rather, they have the ability to supply information on their current state and configuration to an outside entity. The correct term is actually "intelligent," as the phrase SmartUPS is a registered trademark of American Power Conversion (APC), which is one of the largest manufacturers of computer UPS systems.
Information supplied by the UPS is passed to a management component, which might be a piece of custom software supplied by the UPS manufacturer, a software component built into a network operating system, or a special network management system. The communication between the UPS and the software can be achieved through a variety of means. Nowadays the most common method is via a special cable that is plugged into the UPS and the serial or USB port of the computer, though other methods such as direct network connection are increasingly becoming more popular.
No one actually refers to UPS systems with no intelligence as dumb, although it would be kind of fun if they did!
Why Use a UPS?
The purpose of a UPS is relatively clear: it conditions and guarantees constant and good-quality power to computer components. This power quality is very important to computers because it addresses three main concerns:
- Hardware damage Fluctuations in power can damage hardware components.
- Data loss As well as damaging the physical hard disk, fluctuations in power can also damage data held on the drive. In addition to damage caused in this way, it is also worth remembering that modern network operating systems make extensive use of caching. Data is held in memory to speed up access, but only while that memory has power to it. Lose the powerlose the data.
- Availability Possibly the most obvious use of a UPS is to guarantee that the system will be available even if there is no utility power.
If a system is not protected from power fluctuations by a device such as a UPS, both data and/or hardware can be damaged.
What Gets Connected?
Before plugging your computer and all peripherals into that UPS, there are a few things to bear in mind. The most important of these is that the UPS is powered by a battery. The more components that rely on the UPS, the shorter the time the battery can keep all of the equipment live. For this reason, you should typically plug only essential components into the UPS, like the CPU itself or those components that maintain the data. Components in general and especially laser printers are not well suited to being attached to the UPS as they draw too much power from the battery in the event of power failure. However, if the need arises, UPS manufacturers can advise on specific solutions that might be able to support this kind of high-draw device.
Some utilities and independent companies offer power-testing facilities for new and existing equipment. If the opportunity presents itself, having power checked in this way before connecting computer equipment to it is a wise move.
UPS Best Practices
UPSs are relatively low maintenance, but a UPS that receives no maintenance is likely to come back and haunt youat exactly the wrong time. One of the most common assumptions about UPS systems is that the batteries last forever. They don’t. If you think about it, it’s not unreasonable. Rechargeable batteries in every other place we use them do not last forever, and UPSs are no exception. So, periodically, UPS batteries must be replaced and, although it’s not a complicated procedure, special considerations must be used when disposing of used batteries.
In most cases, if you buy replacement UPS batteries from your UPS manufacturer they will accept your old batteries from you for safe disposal. If, for any reason, you can’t take advantage of such disposal services, be sure to observe local ordinances and dispose of your used batteries in a safe and responsible manner. Although the actual battery life will normally be between four and six years, this can vary greatly depending on how the UPS is used.
When it comes to power protection, the Cadillac device is certainly the UPS. However, many of us have Cadillac tastes on a Pinto budget and that’s where surge suppressors come in. Surge suppressors are designed to help filter out power spikes and surges, and reduce line noise. Surge suppressors are not as versatile as a complete UPS solution; however, they are able to protect against everyday power-related problems. This makes them very useful in protecting nonessential systems from damage so you can reserve the expensive UPSs for protecting servers and the like.
The effectiveness of surge suppressors varies greatly, with the underlying rule being the more you pay, the better protection you have. The cheaper surge suppressors are really nothing more than a regular power bar with limited ability to handle spikes or surges. It really is a matter of getting what you pay for. Figure 3-2 shows an example of a surge suppressor.
Figure 3-2 A surge suppressor is the minimum level of protection a computer should have against power irregularities. (Image unavailable)
Surge suppressors are often bought as separate devices, although many UPSs have surge suppressors built in.
One big power spike can wipe out your surge suppressor. In case of an electrical storm, the surge suppressor might not be able to protect the system. Your best option is to unplug the PC and wait for calmer skies.
When you start to work with computers you will soon find out that you have plenty of spare hardware components lying around. These components often have to be reused and are invaluable for quickly fixing problems. To be effective, however, these components need to be in working order, and proper storage helps to ensure that they work as well as they did when you put them away.
The threats to computer hardware are the same when they are in the computer system as when they are out. These threats include water damage, ESD, and so on. When storing components such as expansion cards, we must also protect against these issues. The best way to store components such as memory, motherboards, or processors is to return them to their original packaging, as when they were shipped from the manufacturerbut how many of us actually have kept the original box and packaging? Not many. In lieu of the original packaging, components should be sealed inside antistatic bags. These bags will prevent the effects of ESD on stored components.
Once inside the ESD bag, it is best to store components in a cool dry place. Too much heat and too much moisture can be a huge problem as you are more likely to get electrostatic buildup in these conditions. If you are storing components such as hard disks or tape cartridges, it’s best to keep them well away from magnetic sources and high-voltage devices. Follow these basic guidelines, and those older stored components will be as good as on the day you bought them.
Safety concerns are not always about those things that can happen to the computer; there are also threats to the technician. Most of the components we work with are more afraid of us than we are of them, but there are some key ones that deserve our utmost respect. These include the system’s power supply and the CRT (cathode-ray tube) monitor.
If you ever work with high-voltage equipment, make sure that the device you are working on is unplugged and that you are not wearing antistatic straps. High-voltage equipment doesn’t really concern itself with ESD, and the straps could actually attract voltage from high-voltage devices.
Whenever a monitor doesn’t work as it should, whether it is too blurry or displaying misplaced colorful lines down the center, there is a temptation to take the case off and fiddle around in an attempt to fix it. However, fiddling is never something you want to do inside monitors; there is high enough voltage inside to kill youeven after it has been unplugged!
Monitors use capacitors that retain a charge even after the device is unplugged. If you absolutely must work on a monitor, you will need to discharge it. The techniques for doing this fall outside the scope of the A+ objectives. Also, make sure the monitor is turned off before even attempting to take the cover off. The bottom line is that monitor repair is best left to those who really know what they are doing and are certified to do so.
Like CRT monitors, power supplies use capacitors that maintain a charge long after they have been unplugged. This makes them as dangerous to work with as CRTs. The problem with power supplies is that they do fail from time to time and the temptation might be to save a few dollars and repair an old one. Don’t be fooled; it isn’t worth it. Unless you really know what you are doing, there is no need to work on a power supply. Most power supplies ship with large yellow warning stickers on them alerting you to the dangers. They are not there simply for decoration.
All power supplies have an internal fan in them, not unlike the fan used to cool processors. On occasion, this fan fails but the power supply is still OK otherwise. In such a case, many technicians choose to replace the fan and continue with the same power supply. Because the actual power supply case has to be removed to do this, it is recommended that even when a fan fails, the power supply be replaced.
Even if only the power supply’s fan fails, it is recommended that you replace the entire power supply and not the internal fan.
If you do find yourself holding a power supply with the case off, make sure that you do not have any ESD straps on and that the device is unplugged.
If you do find yourself working with a monitor or power supply, ensure that the power is disconnected and you are not wearing any anti-ESD devices.
We are constantly upgrading our computer components, from monitors to printers, but how much thought do we give to actually getting rid of that old equipment? Many of us don’t really know how and end up storing those old monitors and printers somewhere around the house. There is a better way. In this section, we look at how to get rid of all that old equipment and in an environmentally friendly way, and in the process, you might even free up some shelf space in your house.
Since the days of the XT 8088, 286/386, and 486 computers, there have been monitors needing to be thrown out. The problem with monitors is that they contain chemicals such as mercury and lead that can contaminate the soil. This greatly restricts where and how they can be disposed of.
There are a few ways to get rid of those older monitors. Perhaps the best is to check if there is a local organization that might need a donation. Some places will be more than happy to get a slightly used monitor to use, and this is a good way of recycling. Also, many communities have a hazardous waste program that can assist you by either taking your old monitor or giving you the name of someone who will. Unfortunately, it can be a bit of work to safely dispose of that old monitor but it is worth it. Such devices have no place in a landfill, and in many cities it is even illegal to dispose of old computer equipment in this way.
Batteries are of course not unique to computer devices, but nonetheless it is important to dispose of them properly. The computer-related batteries we need to get rid of periodically include the UPS battery, laptop batteries, and even the battery on your motherboard. These batteries contain chemicals including mercury, lithium, and nickel-cadmium, all of which can and will contaminate water and soil. For this reason, they should not just be thrown out in a landfill site. To properly dispose of batteries, you need to follow local hazardous waste guidelines and most often take the batteries to a recycling depot. UPS batteries are of a particular concern and must be carefully disposed of as in many cases they are very largesome as large as truck batteries.
Some companies go through toner kits and cartridges as fast as they go through coffee filters. Even the average home user can go through a few each month. The end result is millions of old toner kits and cartridges that have to be disposed of. Unfortunately, each of these old cartridges still has a little toner left in it that can contaminate soil and water. Moreover, the plastic and metal that they are made of can take thousands of years to decompose. The bottom line is that there is no room for these in a landfill site either.
Today, perhaps more to save money than for environmental concerns, many people are refilling toner and ink cartridges and reusing them. This form of recycling is very effective in terms of reducing the number of toner kits and cartridges being disposed of. However, there is a common complaint when using refilled cartridges. The print quality is often not as clear as with a new one, and refills can be harder on the printer than new cartridges. Still, for many companies and home users, refilling old cartridges is an ideal environmental solution, not to mention an effective way of saving money.
Many local print shops and even the manufacturer will often buy back or at least take used print cartridges and resell them. This is often the easiest method to get rid of them. Another option is to dispose of them according to local hazardous waste guidelines.
There are not a huge number of chemical solvents and cans used in the computer world, but there are some, such as a used can of compressed air or xylene, which is sometimes used for cleaning rollers on dot matrix printers. When you do come across such chemicals and cans, you will need to dispose of these in a similar fashion as any other hazardous household product. Many local communities sponsor hazardous waste drop-off sites. These are ideal for disposing of old computer chemical solvents.
Material Safety Data Sheet
To help us decide how to dispose of harmful products and components, we have the material safety data sheet (MSDS). An MSDS is a detailed document that contains instructions for handling, transporting, and disposing of particular products. MSDSs are often shipped with a product, such as a monitor, but if not, are generally available from the manufacturer. You can use your favorite Internet search engine to find an online MSDS. Alternatively, you can .
One of the acronyms you are likely going to encounter over and over when flipping through books that deal with PC hardware is ESD (electrostatic discharge). ESD is a natural enemy to computer hardware and protecting against the ESD threat is an important consideration for PC technicians.
Have you ever moon-walked across a nylon carpet and then opened the door? Of course you have. If the result was a spark between you and the doorknob, congratulations, you have achieved ESD. The spark that bridges the gap between your finger and the doorknob is static electricity, and it can damage almost every component in your PC. Even if you are not given to doing Michael Jackson impressions, just making normal movements or not moving at all can cause a static buildup in your body. The static keeps building until it can discharge itself into something made of metal. Examples include memory chips, hard drives, expansion cards, and just about every other component of a computer system.
One of the scariest aspects of ESD is that if a device or component receives an ESD charge, it might notin fact, most usually will notstop functioning immediately. Instead, it sits inside your computer, just waiting for the worst time to stop working. This is known as degradation, which refers to the fact that the effects of ESD are not felt right away but over time they get worse until the component fails. This delayed reaction to ESD is perhaps why people are not more careful when observing ESD precautions. If the results of ESD were more immediate, or more evident, perhaps everyone would be just a little more careful.
Hidden ESD can really make your life difficult, as a component could fail and troubleshooting could be very difficult. Of course the effects of ESD are not always subtle. Improper handling of a memory chip can immediately prevent the module from functioning, and you are left wondering if that new 256-MB RAM was faulty when you bought it or was handled wrong. When ESD causes the immediate malfunctioning of a component, it is called a catastrophic failure. Although the immediate failure of a device seems more dramatic, it is often better than the degradation of a component. In terms of troubleshooting at least, it makes things a bit easier.
Dust and other debris inside your computer case can cause a hidden ESD effect. Over time, the dust can hold a small electric charge and this will eventually begin to degrade the performance of internal components.
Over the years, there have been a number of methods designed to assist in the struggle against ESD. Different ones are used for different situations, but whenever hardware is handled, one of the following methods and products should be used.
- ESD wrist strap Antistatic wrist straps are designed to filter out static charges and safely discharge them. An ESD wrist strap has a strap that fits around your wrist (bet you could have guessed that) and an attached cable. The cable attaches to an earth ground such as the grounding wire of a wall outlet. The cable uses a 1-mega-ohm resistor to negate the effects of ESD.
- Antistatic mat For those that do not want to wear antistatic jewelry, you can use an antistatic mat. When you use an antistatic mat, the component you are working on is placed right on top of the mat. The function of the mat is to dissipate the charge of anything that might come into contact with it. Like the ESD wrist straps, ESD mats use a cable to attach to a grounding source. A variation on the antistatic mat is the antistatic floor mat. A technician would be required to stand on a floor mat to prevent ESD.
- Antistatic spray You can also buy an antistatic spray; it’s kind of like an antistatic deodorant. The function of antistatic spray is to remove the static effect from clothing. Antistatic spray is not as effective as the antistatic mats or wrist straps.
- Antistatic bag While most technicians choose not to use antistatic bags, they are worth another mention in this section. When working with components, it is best to leave them in their antistatic bags as long as possible. When not working with components, it is always best to leave them in their antistatic bags. Some people choose to take components out of their antistatic bags and place them on the outside of the bag when working on them. However, the outside of the bag offers no ESD protection.
- Denatured alcohol is often used to clean floppy drive heads and contacts and connectors.
- Regular glass cleaner can be used to clean the display screen of a regular CRT monitor but never an LCD screen.
- The plastic or metal casing housing computer equipment is best cleaned using a damp cloth and a little soapy water.
- Computer equipment should be completely turned off and unplugged before cleaning. It should not be plugged back in again until it is completely dry.
- The most accepted method of cleaning contacts and connectors is to use a lint-free swab and denatured alcohol.
- Non-static vacuums are specialized vacuums designed for cleaning the inside of computer equipment and peripheral devices.
- Compressed air is often used to blow dust out of the computer case or other hard-to-reach areason the computer, that is.
- Computers are susceptible to a variety of power-related problems including sags, spikes, surges, brownouts, noise, and blackouts.
- UPSs use a battery to keep computer equipment functioning in the event of a power failure.
- UPSs can be offline, with no management features, and online, offering a full range of management capabilities.
- Non-mandatory equipment such as monitors and laser printers should not be connected to the UPS.
- Surge suppressors are designed to filter out power spikes and surges.
- Electrical storms can damage a surge suppressor. In the event of an electrical storm, unplug all computer equipment.
- Components should be stored in their original packaging or in antistatic bags.
- High-voltage equipment such as monitors and power supplies use capacitors and should be left to professionals.
- Computer equipment should be disposed of using local hazardous waste guidelines and not in the landfill.
- Which of the following are you most likely going to use to clean a mouse ball?
- Compressed air
- Damp, soapy cloth
- Denatured alcohol
- You have decided to repair your own monitor. Before starting to work, which of the following must you ensure you do? (Choose two.)
- Unplug the monitor.
- Discharge the monitor.
- Wear an antistatic device such as an ESD wrist strap.
- Refer to the MSDS.
- You hear on the news that there is going to be an electrical storm. What is the best way to protect your computer?
- Attach a surge suppressor.
- Place the computer on an ESD mat.
- Attach a grounding wire between the computer and ground on the wall outlet.
- Unplug the computer system.
- Which of the following components are you most likely to connect to a UPS system?
- Laser printer
- CPU tower
- Bubble jet printer
- You have two old monitors stacked up in your garage. What is the proper way to dispose of them? (Choose two.)
- Donate them.
- Try to repair them and sell them.
- Follow the instructions as presented by the manufacturer’s MSDS.
- Dispose of them in the local landfill.
- Which of the following best describes a sag?
- A drop in power supply that only lasts a short period
- A sharp and very sudden increase in line voltage that pushes the supply voltage above an acceptable threshold
- A drop in supply voltage that lasts more than a few seconds
- Complete power failure
- You need to clean the inside of the computer case. Which of the following are you likely to use?
- Non-static vacuum
- Compressed air
- Denatured alcohol
- Which of the following can a UPS not provide?
- Short-term power to components
- Protection against power sags
- Long-term power to components
- Protection against power spikes
- Why would you choose to use a vacuum designed for computers rather than a regular vacuum?
- Computer vacuums are cheaper.
- Computer vacuums are specifically designed for dust.
- Computer vacuums have less ESD.
- Computer vacuums are smaller.
- Which of the following best describes an online UPS?
- Online UPSs last longer than offline UPSs.
- Online UPSs always filter in power to components.
- Online UPSs are cheaper.
- Online UPSs produce less ESD.
- Which of the following would be methods used to clean contacts and connectors?
- Emery cloth
- Denatured alcohol
- Soapy water
- Which of the following best describes a power brownout?
- A sharp and very sudden increase in line voltage that pushes the supply voltage above an acceptable threshold
- An unacceptably large increase in supply voltage that lasts longer than a spike. This condition is also known as a swell
- A drop in supply voltage that lasts more than a few seconds
- Interference that causes the supply voltage to be inconsistent
- Which of the following would you install to manage power surges?
- Online UPS
- Line suppressor
- UPC system
- Surge suppressor
- Which of the following are not a commonly found antistatic measure?
- Antistatic mats
- Antistatic collars
- Antistatic wrist straps
- Antistatic floor mats
- A user calls you to tell you that her PC has "gone quiet," but is still running. Upon investigation, you determine that the fan in the power supply is no longer running. What should you do?
- Replace the fan.
- Do nothingthe system will run adequately with just the passive cooling features.
- Replace the power supply.
- Reverse the polarity of the fan so that the motor runs in the opposite direction.
Answer b is correct. The best way to clean a mouse ball is with a little soapy water and a lint-free damp cloth. It is important not to replace the ball until it is completely dry. Answer a is incorrect; compressed air might be able to blow a bit of dust from the surface of the ball but the soapy water can get the surface of the ball cleaner. Answer c is incorrect as the denatured alcohol can harm the mouse ball. Answer d is incorrect as an eraser can change the shape of the mouse ball.
Answers a and b are correct. Before working on a monitor, you have to make sure that it is unplugged and that you have discharged it. Remember that the CRT monitor uses capacitors that maintain a charge even after the device is unplugged. Answer c is incorrect; you should never wear an antistatic device when working on high-voltage equipment. Answer d is incorrect; the MSDS is a document that provides information on disposing of equipment, not fixing equipment.
Answer d is correct. In the case of an electrical storm, it is best to unplug all of the components from the wall socket. This includes all cables, even the modem. Answer a is incorrect as in the event of an electrical storm the surge suppressor might not be able to protect the device and might be damaged in the attempt. Answer b is incorrect, as an antistatic mat will not help electrical surges from a storm. Answer c is incorrect, as attaching grounding wires anywhere would not help in the event of a storm.
Answer c is correct. A UPS system is powered by a battery, and the less equipment attached, the less power is drawn from the battery in a power failure. With this in mind, the most critical components to hook up to the UPS are those that maintain the data, such as the CPU tower itself. Answers a, b, and d are incorrect; monitors and printers draw too much power from the UPS and are not mission critical in terms of availability.
Answers a and c are correct. A good way of recycling old computer equipment is to donate it to someone else who can use it. Failing that, you should follow the instructions provided in the MSDS to ensure safe disposal. Answer b is not correct. Monitors hold very high charges and should not be repaired unless you have received specialized specific training that allows you to do so safely. Answer d is not correct. Monitors contain numerous chemicals and pollutants that make them unsafe, and often illegal, for disposal in a landfill.
Answer a is correct. A sag is a short drop in power that can often cause the computer to reboot. Answer b is incorrect; a spike is a sharp and very sudden increase in line voltage. Answer c is incorrect; this describes a brownout. Answer d is incorrect as it describes a blackout.
Answers a and b are correct. Both non-static vacuums and compressed air are safe and effective ways to clean the insides of a computer system. Answer c is not correct. Denatured alcohol is used for cleaning components such as the read/write heads of floppy drives, not for cleaning the inside of computer systems. Answer d is incorrect. Human breath contains moisture, which does not make it ideal for cleaning inside of computer systems.
Answer c is correct. A UPS is powered by a battery and therefore cannot supply long-term power to components. The function of the UPS is to provide the time necessary to shut the system down cleanly and potentially save data and hardware. Answers a, b, and d are functions that a UPS can provide.
Answer c is correct. Computer vacuums are specifically designed to clean without producing harmful ESD. Answers a, b, and d are not valid.
Answer b is correct. Online UPS systems always filter a bit of power to components and in case of power failure, components can automatically shift to battery power. This is not true of offline UPSs. Answers a, c, and d are invalid and not necessarily true of online UPS systems.
Answers a and d are correct. Both an emery cloth and a little denatured alcohol on a lint-free swab are acceptable methods of cleaning contacts and connectors. Answer b is incorrect because erasers often leave as much residue as they clean off. Answer d is incorrect; water is never good to use on or near electrical circuitry.
Answer c is correct. A brownout is a drop in the voltage supply that lasts more than a few seconds. Brownouts are a common problem in many areas. Answer a is incorrect; this describes a power spike. Answer b is incorrect as this describes a power surge. Answer d is incorrect as this describes power noise.
Answers a and d are correct. A line conditioner or an online UPS system can be used to filter out power surges. Answers b and c are not valid power devices.
Answer b is correct. Antistatic collars are not commonly used antistatic measures. Answers a, c, and dantistatic mats, wrist straps, and floor matsare all commonly used in the war against ESD.
Answer c is correct. Even though fans in power supplies can be replaced, the power supply enclosure has components that can give you an electric shock. Therefore, you should not replace the fan unless you have received specialized training that allows you to do so. Answer a is incorrect for the same reason noted in the explanation of answer c. Answer b is incorrect. Power supplies must be cooled to run effectively. Answer d is not valid. Reversing the polarity would cause the fan to spin in the opposite direction, if it were working, which it is not.