|Symptoms and Problems|
Memory problems are also detected when POST runs at boot time. These types of errors are usually preceded by a 2**, again where the ** can be any set of numbers. Check the descriptive message that comes with the error code and proceed accordingly.
PRESS <F1> TO CONTINUEYou can check that the keyboard connector is snugly secure in the socket, but if it is, then you may need to replace the keyboard itself.
Exam Watch: Keyboard errors usually generate a 3** error code when POST runs at boot time.With sporadically functioning keys or sticking keys, you need to give the keyboard a good cleaning. This type of problem is fairly obvious, as most customers have a nasty habit of eating and drinking over keyboards. You can purchase a keyboard cleaning kit at any computer or electronics store to use, but if the problem isn’t resolved after a cleaning, you will have to replace it. The good news is that keyboards are relatively inexpensive items and that any replacement takes less than one minute.
|Adapter card, if any|
If another device is using the same IRQ or I/O address as the mouse, then it probably won’t work at all. This is because the results are being returned to the conflicting device. Try checking IRQs and I/O addresses with diagnostic software to ensure that there is not another device using either of these.
Device drivers control how the mouse communicates with the processor. If the driver is configured incorrectly, such as a wrong address or an incorrect sensitivity setting, the mouse will have slow to non-functional symptoms. In addition, if the device uses an adapter card, there may be a problem with the card itself. If you suspect that this is the case, you can try to replace the adapter card and see if the problem is resolved.
If you are working on a personal computer, the trackball is a peripheral device and is not integrated into the keyboard. If the device is non-responsive, check the connection into the computer to ensure that it has not come loose. Also, check any adapter cards and device drivers that are associated with the trackball. Usually, there is a device driver configuration error or driver corruption that causes the problem. You can also check these items with a sporadic problem, but most likely you will need to clean the device to resolve the problem.
|Dirty scanner surface|
|Cable and power connections|
|Adapter card, if used|
Always ensure that the cable connection from the scanner to the computer is properly attached. A loose connection usually results in a non-responsive scanner. However, if you are diagnosing a flat-bed scanner, you also need to check the power connection if the device does not power up.
Adapter cards do the work of translating signals between the scanner and the computer. As such, they are good suspects when you encounter communication-related errors. However, most problems with scanners that are not resolved by cleaning the unit are device-driver related. The driver is the software interface between the computer and the adapter card, and may have been inadvertently modified by the customer. If not, ensure that the driver is not corrupted. If you have determined that the device driver is corrupted, you can reinstall it from the original floppy or floppies that came with the scanner.
If touch pads need repair, usually a good cleaning with a damp cloth (no detergents) will resolve the problem. You can verify that any device driver or application software has a correct configuration, but beyond this you may need to replace the device.
|Dirty read/write heads|
|Cabling or connection errors|
|Floppy controller card|
|Device Driver errors|
Media errors can also be caused by dirty read/write heads on the floppy drive. Dirt can get into a computer through the vents used to pull in fresh air, and as such will stick to the read/write heads. Also, while floppies have less chance of getting dirty from the plastic encasement, there is still some dirt deposited on the media when it is in use by the drive. Floppy drive cleaning kits can be purchased rather cheaply at any computer store, and you should follow the manufacturer’s instructions for using them.
Another thing to check for is that there is nothing stuck in the drive itself. Sometimes, people put items in the drive that do not belong there, such as the wrong type of media. Small children are also notorious for placing items into a floppy drive just as they are with VCRs. However, even though you want to believe that people wouldn’t do these types of things, you cannot take anything for granted and must check that no foreign objects have been placed into the drive.
Cabling can also lead to drive problems. If you have just installed a floppy drive and you are experiencing a problem with the drive, such as the drive light won’t go out, you probably have the cable on backwards. The red stripe on the floppy cable must be connected to pin 1 on the adapter and on the drive. Also, there will be times when you think that a cable is firmly seated on the drive, or on the adapter, and it might be a hair off. This can cause communication problems between the drive and the adapter. Try pressing on both connections to see if they move at all.
If the drive isn’t getting power, it won’t work. Sometimes the power connector isn’t properly seated in the power connection. You can attempt to push the power connector to see if it moves. If it doesn’t move, and the drive still isn’t getting any power, then you have to replace the drive.
Communication problems between the drive and the adapter may also be caused by an improperly seated controller card. You must gently, but firmly, press down on the adapter card. If it hasn’t moved, then you may want to check the contacts. Contacts can get dirty and may require cleaning with isopropyl alcohol. If you suspect that the contact might be defective, you can attempt to check it using a multimeter. However, if you believe that you have a problem controller card, you can test it by installing a second floppy drive. If you can successfully use the second drive, then the controller probably isn’t the problem.
If the problem doesn’t fit into any of the previously mentioned problems, you must check for possible software problems. The device driver used by the operating system software may have become corrupt, in which case you can try reinstalling the driver. However, if the computer has been losing its BIOS settings from a dying CMOS battery, you have to enter the SETUP program to re-enter the settings. With newer computers, this shouldn’t be a concern as the BIOS can usually auto-detect the drive. Unfortunately, older computers require you to re-enter these settings manually.
At this point, if you are still encountering problems, then the drive itself is at fault and must be replaced. The good news is that floppy drives are relatively inexpensive items, and they only take around 15 minutes at most to replace.
|Hard drive controller or SCSI interface|
|Fragmented or corrupt drives|
Communication takes place between the hard drive and the controller via a cable. This cable could be loose or may have gone bad. This is also common with newly installed drives rather than those that have already been functioning properly. Check the cable connection to ensure that it is connected properly, and if it is try swapping cables. If you have more than one hard drive in the computer, verify that the master/slave configuration is correct.
The controller card may also be a problem for the hard drive. Verify the address settings for the controller and ensure that there are no conflicts with another device. If another hard drive is attached to the controller and functioning properly, you probably do not have a controller problem.
If you are working on a SCSI device, verify the device driver configuration, as well as check that the proper driver is in use. If you have a mix of drive types, you cannot use the same driver for the mix. Each drive type needs to have a driver loaded for that specific drive. Symptoms may include sporadic problems with the drive itself. Also, look at the BIOS settings. Most of the time, this is not a problem. However, if the computer has recently lost its BIOS settings, you may have to manually ensure that they have been reset properly.
If you feel that you have file corruption or bad sectors on the disk, you can use a utility such as Microsoft’s Scan Disk or Norton Disk Utilities to repair or remove damaged files, as well as check and mark any bad sectors on the disk. File corruption or bad sectors can be caused by several things: corrupted or invalid device driver, faulty controller cable, an incorrectly configured controller, or even a computer shutdown while the file is in use. A scanning utility can be used to check each sector on the disk and allow you several repair options, depending on the software. If the utility finds a bad sector on the disk, it flags the spot as bad so that it is not used by the drive.
|Dirty read/write heads|
|Cabling and power connections|
If you are able to rule out the cartridge, the next step is to inspect the power connection. If the device is not getting power, it will not work. Try checking the power cable and ensuring that the power connector is firmly seated. If the connector is not properly seated, it may be slightly shaken as the drive motors are in operation, and thus cause sporadic power problems. Also check to see if a power strip is in use, as surges or lapses in power can "trip" them, causing them to require a reset.
Another possibility is the cabling from the drive to the adapter card. If the cables are not connected properly, then the drive will experience communication problems. Try to push down on all the connections, as well as on the adapter card itself, to see if there is any perceptible movement. If there is, you have probably found the problem, although sometimes the cable itself may be defective. In this case, replace the cable to see if the problem goes away.
Because device driver software resides on the computer’s hard disk, there is also the potential for the driver to become corrupted. There are two ways that you can check this angle. The first method is to verify the software configuration; the second method is to reinstall the driver. Always check the software configuration first, as it is also possible that the customer may have inadvertently made a configuration change, referred to as operator error. If you see any garbage characters in the configuration, then you definitely have a corrupt driver and must reinstall it. However, if the values have been slightly altered, you probably have an operator error.
|Cable and/or connectors|
One of the most common problems reported to the technician with regards to CD-ROMs is that the customer cannot read a CD-ROM disk. There are several things that can cause this, but usually having the customer verify that there is, in fact, a compact disk in the tray or that it was not inadvertently inserted upside down commonly solves this problem. In addition, if the customer is using a CD-ROM tower or a disk changer, they may have forgotten to perform a software mount on the CD, which is usually performed with a MOUNT command. When there is still a problem accessing the disk, try having the customer read from another disk to ensure that there is not a media problem. If the drive can successfully read a second CD, there may be a problem with the original disk through an incompatible CD-ROM format or a corrupted disk.
When you cannot successfully access a second disk, verify that you can hear the motor on the drive. This is usually a high-pitch whirring sound that is easily heard. If you cannot detect the noise, there may be a problem with the drive itself or its power connections. However, if you do hear the drive, try checking the cabling to ensure that there is not a loose connection. Also, do an I/O address check to ensure that there isn’t an address conflict going on with another device.
If none of these measures solve the problem, verify that the proper device driver for the CD-ROM and/or the controller card has been installed and that it is configured correctly. Ensure that the driver hasn’t become corrupted as a result of a bad spot on the hard disk. If necessary, try to reinstall the driver and see if the problem is resolved before replacing the CD-ROM drive.
If the computer doesn’t boot after you have installed a CD-ROM, you may have either an address problem, a cable problem, or a connector problem. First, make sure that the address has been configured properly and that there are no address conflicts with another device. Next, check the cable between the controller board and the drive itself, ensuring that it is properly attached with the red stripe facing pin 1. Verify that the power connector is snugly in the socket. Lastly, ensure that the proper device drivers have been installed for the drive and the controller board.
When the computer will boot, but the CD-ROM drive isn’t being recognized, you may have a communication error between the computer and the drive. If you have diagnostic software with you, it is easier to pinpoint the problem. If not, the first thing to check for are the device drivers and their configurations. Ensure that you do not have any conflicts with another device, such as an incorrectly addressed drive. Also, verify that the controller board does not have a problem, whether it is the cabling, addressing, or the board itself.
You can also ensure that the device driver is not corrupted, and whether it has to be reinstalled from the original disk. If you are working with an older card, you may want to check the manufacturer’s Internet site to see if the driver has been updated. However, do not rule out the possibility that the card is defective, even if it is a new card.
|Toner cartridges or ink ribbon|
|Application software configuration|
An impeded pathway can also cause paper jams, but usually the jam occurs in the same location every time. It only takes a small bit of paper to cause the problem, and usually you have to take the printer apart to find it. If you open the printer and find a lot of paper dust, you need to clean the whole unit to ensure that the dust isn’t the cause of the problem as well, as dust and dirt can carry a small charge and cause the paper to stick to metal parts just enough to cause a jam.
When you encounter a printer that produces blank pages, the usual suspect for dot-matrix printers is the ribbon or the print head. The print head is made up of pins that strike the ribbon onto the paper to form text or graphics. These pins can get dirty and stick, and if the characters are missing spots, you should clean or replace the head.
Printers are basically mechanical devices, whether you are working with a dot-matrix or a laser printer. As with any mechanical device, parts become worn out over time and heavy use. It is important that you check for any signs of wear on all internal components and replace any that exhibit symptoms of deterioration, as worn out parts can also cause an excessive amount of page jam. In addition, ensure that all mechanical parts are properly lubricated.
Cabling can be a problem when you are faced with a non-responsive printer. The connectors between the printer and the computer may have been jostled loose enough that the signals are not being transmitted or received properly. This includes the power connectors to the printer.
Interface cards are also responsible for proper communication between the computer and the printer. Check the card to see if it has failed. Also, with the new printer Transmission Control Protocol/Internet Protocol (TCP/IP) adapter cards, which enables a printer to communicate using the popular TCP/IP communications protocol, ensure that the interface card has not lost its settings. This is especially true if it is a network printer, as you may not know who has the ability to modify configuration settings. An example might be a printer that has mysteriously lost all configuration information, resulting in the whole office being unable to print to it. Symptoms of this kind of problem are the inability to print to the printer or receiving garbage characters for output.
Software applications also have printer settings. Most of the newer software packages use the operating system information to enable a user to choose between various printers to which they may be connected. However, some of the older packages may require that you specify these settings. Verify all software applications that have a problem interfacing with a printer.
|Power and power connections|
|Brightness and/or contrast controls|
|Video adapter card|
Another possibility is that the customer has the brightness and/or contrast controls turned all the way down. This is another common problem with video displays. Readjusting these controls may revive the display and save quite a bit of time and money in the repair. If the monitor still does not work, try replacing it with one of the same type. If another monitor works, then the original monitor needs repair. Note that you must check with the customer as to whether or not it is under warranty. To get a replacement, most manufacturers require the client to ship the original monitor back. Never try to repair the monitor itself unless you have experience in monitor repair, as monitors are high-voltage equipment and you could accidentally injure or kill yourself.
Monitors use a sync frequency to control the refresh rate, which is the rate at which the display device is repainted. If this setting is incorrect, you get symptoms such as: a "dead" monitor, lines running through the display, a flickering screen, and a reduced or enlarged image. This setting is configured through the device driver. In order to ensure that you are using the correct frequency for the type of monitor being used, consult the vendor’s documentation.
If a monitor swap doesn’t do the trick, you may have a problem with the cables or the adapter card. First, check that all of the cables are properly seated before attempting to replace them. This includes the power cable, as the power cord probably connects to a power strip. Make sure that the power strip is on and that it hasn’t been "tripped" by a momentary power lapse.
If you suspect that there is a video adapter problem, check that the card has been correctly configured. This requires you to consult with the manufacturer’s documentation to ensure that all jumpers and/or DIP switches are properly set. You may also want to check that any memory installed on the card hasn’t suffered from chip creep, and gently press on the memory chips to ensure that they are seated correctly. When you have determined that the card’s configuration is accurate and that any on-board memory is seated, proceed to swap video cards. This should solve the problem of a "dead" monitor.
Sometimes you will be called on to diagnose a monitor that has poor image quality. As stated earlier, monitors do not last forever. You can still check for such problems as a brightness/contrast change and cable problems, but most likely the problem lies in either a defective adapter card or a configuration error. To ensure that the adapter card is not the problem, follow the procedures discussed in the previous paragraph. However, when there is a configuration error, it is usually found in the device driver. Check the configuration of the device driver. Remember, if you spot any garbage characters in the configuration information, you probably have a corrupted driver and must reinstall it. However, the most common cause of configuration problems after a monitor has been working awhile is operator error.
With a nonfunctional modem, the first thing to check is the power connection. If it is an external modem, you can power on the modem and see if any of the lights on the control panel are lit. If none of the lights come on, the modem isn’t getting power and you must check both the power connector leading into the modem as well as the connection to the power outlet. Sometimes, the power outlet may have a problem and you can move the connector to another outlet. Power strips cause another problem if there has been a momentary lapse or surge in power and may need to be reset. If the modem still has no lights, then you have to replace the modem. However, if you have an internal modem, you have to open the case and gently push down on the power connection. At this stage, try using the modem to make a connection to see if the problem is resolved.
The next phase in modem diagnosis is to check on the cabling. Sometimes, the cable connections between the modem and the computer become loose, especially if the computer is moved around. This also includes the phone line leading into the modem as well as the wall socket. A common problem with phone lines is that the locking tab on the cable itself breaks off, resulting in a loose connection. In both cases, you need to replace the problem cable and test the modem again.
Besides the phone-line cable, there may be another problem stemming from the phone line itself. With a sporadic problem, it could be that the modem and the office fax are hooked up to the same phone line, which is commonplace in the office environment. If a fax machine is in use when the problem occurs, you may be encountering this type of situation. Another possibility is that the modem could be sharing a phone line with a regular phone, as is typical in home/office environments, which may also explain some sporadic problems. If either one is the case, you may want to recommend that the customer lease a separate line for the modem. However, if this isn’t the case, should physically check the phone line itself. To do so, simply unplug the phone line from the modem and plug it into a regular telephone, then pick up the handset. If you do not get a dial tone, the line is dead and you need to turn over the problem to the phone company.
Connection problems are the most common problem you will encounter when diagnosing a modem. Some of these problems are caused by static, or noise, on the phone line itself, particularly on the Hayes 14.4 Optima modems. When you connect to another modem, both of the modems have to agree on the method of communication used, called handshaking. When noise is present on the line, the analog signals that are transmitted back and forth between the modems may be misinterpreted and result in a failed connection. Static can also cause problems in the transmission of data for the same reason, leading to bad data transmissions, dropped connections, and garbage characters appearing at random intervals. You check the phone line for noise by plugging the phone cable into a regular phone and picking up the handset. Listen for a minute and see if you can hear any noise on the line. If there is, you must get the phone company to look into the problem.
If none of these solutions resolve the problem, you need to check the I/O port used. In order to do so, you can either use diagnostic software designed specifically to test I/O ports or you can try a null modem cable. A null modem cable is a special cable that has the send and receive lines reversed on the connector. To use it, merely install the cable and try using the modem software to establish a connection.
Another consideration with modem problems is the communication software itself. Ensure that the baud rate, stop bits, parity bits, and communication protocol used are correct for the session that the customer is attempting to establish. The most common symptoms for an incorrect configuration is receiving garbage characters after making a connection. For example, if the software is configured to use an Even Parity and the connecting modem expects the parity to be set to None, you will see a steady stream of garbage coming across the screen right after connection. Try different configuration settings if the customer is unsure of the communication parameters, but only after you have noted the current configuration somewhere.
An important item that should be checked is the device driver installed in the operating system software. A corrupt, or improperly configured, driver causes many of the symptoms that have been discussed. Also ensure that you check the IRQ and I/O address of the modem as it is possible that there is a conflict with another device configured in the system. Sometimes a reinstall of the driver solves the problem, but be prepared to replace the modem if it doesn’t.
The error codes that you see on the screen falls into a particular range that can be associated with a specific component. Table 2-1 lists these ranges and their associated devices.
|100-199||System board problem|
|400-499||Video problems, monochrome|
|500-599||Video problems, color|
|600-699||Floppy disk errors|
|1700-1799||Hard disk problems|
Because device drivers are stored on a hard disk, you want to ensure that the driver has not become corrupted. This occurs when the hard disk has begun to fail or is experiencing problems, and sometimes when a computer has had a power surge. If you see garbage characters appearing in the device driver description or in its configuration, then it is definitely a corruption problem. Try reinstalling the driver according to the vendor’s instructions.
I prefer to have a sturdy briefcase, which is about 1 ½’ by 2’ by 6". Do not pick a flimsy material for this case, because it will most likely be used a lot. Do not buy tools haphazardly. Stick with the kits that you can find in a computer store. Try and get the most tools that you can afford. These kits range from simple to quite elaborate. You’ll do well in the $30 to $50 range.
You also need your array of disks. Get startup disks for all the operating systems that you are using. Also, get disks with drivers for all the hardware that you think you’ll encounter. Get disk holders for these disks. If you are working on systems with CD-ROM’s, get a CD-ROM holder and pack it with ten of the best CDs for repairs. Pack your bag with compressed air, anti-static wrist guards, and books. Why books? Because there are some indispensable books out there that will save you a lot of time when you are in the field. Try and get a small book that list all the manufacturers settings for computers, hard drives, error codes, company phone numbers, and so forth. These can be found for under $10. Most operating systems have good books that can be used as reference. Find a good one and keep it in your case. Also, include miscellaneous items that you will always need. Converters, networks cables, computer cables, bolts, adapters, extenders, phone lines, and the like will all prove handy and will save you a trip to go back and get what you need.
Also in this case keep plenty of pens and a note pad. I’ve seen some techs even carry a sandwich in their repair cases. This is nice if you happen to have a really big repair around lunch time. Always keep your eyes on what other people carry around in their cases. Just make sure you can carry all that you put in it, or you may end up having to move equipment as well as carrying your case.
— By Ted Hamilton, MCP, A+ Certified
The first step in diagnosing the problem is to gather as much information on the problem that you can. These are your "clues" that help point you in the right direction. As with any good mystery, you need to question the customer about the problem. Items that you want to include in your information-gathering constitute the computer’s environment as well as the symptoms exhibited before, during, and after the problem. We discuss both of these in detail in the following subsections, and round it off with some of the more common problem situations in which you might find yourself.
If the physical environment is not a problem, you need to verify the computer environment. One of the first things you can check is if there were any changes made to the system of which you might not have been informed. This enables you to verify that any modifications that may have been made aren’t the source of the problem. This could be in the form of hardware or software upgrades, including any changes that might have been made to a network to which the customer connects.
If the customer is on a network, find out if software applications are loading from the network. Sometimes, a software upgrade may have put the newer application in a different directory and the new drive mappings haven’t been properly implemented. If their operating system loads directly from the network, it is also possible that a device driver has been moved or deleted. Ask the customer if it is a constantly recurring problem or if it is a sporadic problem. Sporadic problems are harder to isolate as they are difficult to recreate.
Verify device drivers and their configurations. Does the customer load their operating system, such as Windows 95, from the network? If so, the device driver may not be in the root directory of the operating system or possibly a different version has overwritten the original one. The customer may have inadvertently made changes to the driver configuration. These are all things that you should check on.
Most error codes occur during the POST diagnostic routing that is performed during boot time. These codes are listed later on in the chapter, but a few of the more common ones are listed in Table 2-2.
|Error Code||Error Message||Description|
|161||CMOS battery failure||CMOS battery needs to be replaced.|
|164||Memory size error||Occurs after a memory upgrade. Run the SETUP program and the error should disappear.|
|201||Memory test failed||One or more of the Random Access Memory chips failed the test. May need to try replacing them one at a time to find the defective chip.|
|301||Keyboard did not respond||Indication that the keyboard probably needs a cleaning.|
|303||Keyboard or system unit error||Indicates a bad keyboard that needs to be replaced.|
|423||Parallel port test failed||Reported with monochrome adapters. Will need to replace the adapter.|
|"My computer is getting a keyboard error."||Either the keyboard needs cleaning, the connection has worked its way loose, or the keyboard must be replaced.|
|"The computer lost its BIOS settings."||This is commonly caused by a low CMOS battery. Replace the battery and reconfigure the CMOS.|
|"My monitor is dead."||Several issues revolve around this one. If it is a power-saver monitor, try hitting a few keys and see if it comes on. Check that the monitor is actually powered on and that the cable connection is secure.|
|"The mouse moves sporadically."||This is either a symptom of a dirty mouse or an incorrectly configured mouse. If it is a configuration problem, you probably have to raise the mouse-sensitivity property higher than it currently is.|
|"My printer won’t print."||Run the printer’s diagnostic routine, or self-test, and see if there is any problem. If it passes, the printer is not at fault and you need to check that the cable is correctly attached. Verify the device driver configuration, and if necessary, the software application’s configuration. If the printer has a TCP/IP adapter card, the printer may have lost its TCP/IP configuration and you have to use the configuration utility and ensure that the settings are still intact.|
|"The output on the page from my printer is fuzzy."||If you are working with a dot-matrix printer, check the print head for stuck pins. However, a laser printer probably needs a good cleaning.|
If you have encountered a problem similar to the reported problem, then use that knowledge to isolate the cause. Once you have encountered a similar problem, you can apply that knowledge to the situation at hand, resulting in a faster diagnose and repair. Some technicians even keep a notebook with them to log problems and their resolutions to reference when a situation is unusual or infrequent. Keeping a log that references specific sites can also be useful, as you may be called on to troubleshoot the same problem you resolved before.
With software problems, you need to check for device driver problems, such as configuration errors or corrupted software. Also, verify any application settings that relate to the device itself. If you suspect that an application is at fault, you may have to reinstall the software to resolve the situation.
|CMOS stands for Complementary Metal-Oxide Semiconductor, ) which is an integrated circuit composed of a metal oxide that is located directly on the system board.|
|Chip creep is a phenomenon whereby a computer chip becomes loose within its socket.|
|Input devices are the easiest types of components to check, as there are fewer things that can go wrong with them.|
|Keyboard errors usually generate a 3** error code when POST runs at boot time.|
|With sporadically functioning keys or sticking keys, you need to give the keyboard a good cleaning.|
|A dirty mouse is the most common mouse-related problem reported.|
|If another device is using the same IRQ or I/O address as the mouse, it probably won’t work at all.|
|If a trackball on a laptop is unresponsive, you have to replace it, which on many laptop machines, also requires that you replace the entire keyboard unit.|
|A dirty scanner surface usually results in smudged or poor-quality images.|
|Most problems with scanners that are not resolved by cleaning the unit are device-driver related.|
|Sometimes the most obvious solution will solve your problem. With most components, the first thing to do is check that the power is turned on or that the power supply is snugly in place.|
|Floppy disks are susceptible to physical and magnetic corruption, giving the customer the appearance of a bad drive with "Error reading disk" or "Error writing to disk" messages.|
|File corruption or bad sectors can be caused by several things: corrupted or invalid device driver, faulty controller cable, an incorrectly configured controller, or even a computer shutdown while the file is in use.|
|Problems that are encountered with tape drive systems include media problems, dirty read/write heads, cable and power connections, controller card, and device drivers.|
|For CD-ROM problems, one good troubleshooting tool that comes in handy is any diagnostic program that may have come with the CD-ROM drive or the controller board.|
|One of the most common problems reported to the technician with regards to CD-ROMs is that the customer cannot read a CD-ROM disk.|
|If the computer doesn’t boot after you have installed a CD-ROM, you have either an address problem, a cable problem, or a connector problem.|
|To diagnose parallel or serial port problems, you need special diagnostic software in order to verify that they are working.|
|The most common problem with sound cards is related to configuration problems with the software driver configuration, which is in the form of IRQ, I/O Address, or DMA channel conflicts.|
|A paper fault can be a symptom of the use of poor quality paper, such as recycled paper, or an impeded pathway.|
|Printers are one of the most complex systems that you will diagnose.|
|When you get a complaint of a "dead" monitor, one of the first things to check (and one of the most forgotten) is to see if the monitor is turned on.|
|Monitors use a sync frequency to control the refresh rate, which is the rate at which the display device is repainted.|
|External modems are easier to diagnose than internal modems, as you can see the signals from the display panel.|
|When one modem connects to another modem, both of the modems have to agree on the method of communication used, called handshaking.|
|A null modem cable is a special cable that has the send and receive lines reversed on the connector.|
|A Power On Self Test (POST) is self test performed by the computer that occurs during boot time. It is used to diagnose system-related problems.|
|Refer back to Table 2-1 and review the error code ranges and components they relate to.|
|The most common problem with the BIOS is when the CMOS battery begins to run low on power.|
|Power supplies include a fan in the unit to cool it down, thus preventing overheating.|
|Device drivers are programs that translate necessary information between the operating system and the specific peripheral device for which they are configured, such as a printer.|
|When troubleshooting computer-related problems, you need to gather all the information that you can from the customer: scrutinize the environment, use your observational skills on the equipment and software, and attempt to recreate the problem itself.|
|Refer back to Table 2-2 and review error codes and their meanings.|
|Patience with users, who usually know little or nothing about how a computer operates, is not just a virtue but a necessity.|
|When you are faced with a computer problem, start with the easiest item to test and work your way upward.|