The Original Guide for Troubleshooting and Repairing Clone PCs
|
Visit the online version of Start Your Own PC Repair Business
|
The Original Guide for Troubleshooting and Repairing Clone PCs |
|
I've been thinking seriously about stringing all of my newer computer troubleshooting and repair pages into an online computer repair course. No certification, if you want an A+, go pay somebody and take the multiple choice test. Just a self-guided course in how to diagnose hardware problems and effect repairs. PC's are actually much easier to troubleshoot these days than when I wrote the old guide below for technicians I was training, because there are fewer discrete parts now and the reliability is much higher. The new flowcharts book which I link above is being used in technical college classrooms as the course text, despite the fact the only illustrations are the black and white flowcharts.
Copyright 1996 by Morris Rosenthal
Notes: This is an old, old guide, originally posted in 1995. This information is intended for the screwdriver fluent only! The author assumes no responsibility for loss of limbs or life, not to mention data or other property, on the part of the reader (you).
Computer power supplies are among the weaker links in clones. The primary symptom of catastrophic failure is complete lack of power to the system (no little lights, no fan turning on power supply, no noisy floppy seeks).
Check the line voltage selection switch (110/220 V) to make sure it's on 110.Push the power cord firmly into the back of the supply and the outlet.
Power supplies will occasionally display this behavior if one of the main system components has developed a short circuit. This may be determined by alternately isolating components from the power supply.
Unplug all of the leads to the drives, and try to boot the system.If no signs of life are present, reconnect the drives, remove the power connectors to the motherboard and try powering up again.
If the power supply fan still doesn't move, it's time to double check that the cord to the power supply is plugged firmly into the supply and into a live outlet (an optimist may even try a different power cord).
Paddle type switches on power supplies are fairly bullet-proof, but the push in types will fail occasionally. Failure is usually obvious, such as the switch not staying in or not popping out. Power supplies of this type should be checked with an ohm-meter or by attaching another switch, before landing on the trash heap.
When replacing a dead power supply:
Make sure the replacement is of an identical form, i.e. physical size of supply, location of switch and connection of switch if it is the front panel push button type.One of the few universal truths in the world of clones is the color coding of the motherboard connectors, P8 and P9. Connect these to the motherboard such the black leads in either connector are adjacent to one another in the middle of the connection block.
Many intermittent failures of power supplies are indicated by noises. The audible noise from the power supply is normally caused by the fan. A steady squeal or loud hum is caused by failing fan bearings. These noises may come and go in accordance with room temperature, humidity, and other environmental factors. When this problem has been identified, change out the supply immediately if it is in manufacturers warranty, because it's not going to fix itself.
Power supplies can last a long time with noisy fans, but failure of the fan can damage more than just the power supply, which will overheat and malfunction when the fan stops. The other key noise produced by the power supply fan is the pitch of the normal drone sound it may make.
If the pitch drops greatly when the drives are being accessed, the power supply is not very healthy, and should be returned if in a new machine.Power supplies can also be afflicted by whistling capacitors, and should be rejected at burn-in or purchase if this high pitched noise is present.
Power supplies can also be responsible for a variety of odd-ball failures. If a machine reboots itself when the table is jarred, or when someone walks across the room, there is a good chance that the short is in the power supply and not in the system. Systems which occasionally freeze up and don't want to power up for a few minutes after being shut off may have a power supply problem, the other likelyhood being an overheated CPU. Systems that boot and run for a very short period of time before freezing may also be blamed on the power supply. A power supply with a faulty ground can cause strange problems, particularly with drives that use the frame for ground.
If a known good floppy or tape drive experiences consistent failures in a system, try running it insulated from the case. The easiest and often only way to trouble shoot a possible power supply problem is to swap it out.
Keyboards are pretty reliable on the whole, given that they are one of the more low-tech. parts of a system. Stuck keys, keys that repeat (bounce) and keys that just don't work at all are pretty easy to spot and are usually highly repeatable. The other obvious failure mode is when the system hangs on booting and displays a keyboard error message.
Make sure that the keyboard is plugged in, that a book or your elbow isn't resting on the keypad, and that the old XT/AT switch on the bottom of older keyboards is set to the proper system type.Some combinations of EEKs' (Extremely Enhanced Keyboards) and the computer BIOS will always produce a boot time error unless keyboard testing is turned off in the CMOS setup. Obvious failures such as these can be easily diagnosed by swapping keyboards.
However, more insidious problems can arise from an intermittent keyboard failure. Somtimes a keyboard failure will mimic failure of the keyboard controller, often called the keyboard BIOS chip. Some keyboards, due to capacitive buildup, or heat related failure, will cease to work while the computer is in use, giving the user the impression that the system has "hung".
A simple test is to check if the mouse still works, is able to pull down menus, etc. If this is the case, the problem is definitely in the keyboard circuit.IF a mouse is connected to the system, leaving a screen saver running will expose the problem (i.e. the screen saver continues to run when you attempt keyboard input).
If swapping out the keyboard does not correct the problem, the keyboard controller chip, which is normally in a dip socket should be reseated, and then replaced if necessary.
Note that actual problems with mouse motion on the screen are usually due to a dirty mouse. If yo have troble getting your mouse to move either horizontally or vertically, clean the mouse and try it again.
Todays motherboards are all surface mount technology, and could practically be labeled "No User Serviceable Parts". For this reason, the only beep codes that are relevant are memory or video failure, and rather then remembering these two, you can just keep a video card and some memory SIMMs' on hand.
Most motherboards have the system BIOS, cache memory, main memory and the clock crystal socketed. A large number also have the keyboard controller and the CPU in sockets. An on-board battery with some type of replacement option is used to power the permanent CMOS memory and clock/calendar.
If the system powers up and gives a series of beeps (8 or 9), with nothing appearing on the screen, change out the video card.If the system powers up and gives 3 beeps with nothing appearing on the screen, replace the memory in bank 0, or temporarily swap it with the memory in a higher bank.
Memory failure outside of the first 64K should not prevent the system from lighting up the display and displaying an error. The most common field failures of motherboards are main memory or battery.
A bad crystal will very rarely cause boot failure or intermittent lock-ups, and should be swapped only before replacing the CPU. On new systems with ZIF (Zero Insertion Force) I'd try swapping the CPU first!A bad BIOS chip can usually be visually identified by a burnt spot on the label over the center of the chip, since their normal failure mechanism is excessive heat. System BIOS chips fail even less often then keyboard controllers, and are not suspect in intermittent failures.
Problems can sometimes be caused by partially inserted CPUs, especially as the larger chips can be difficult to insert. Diagnostic failures involving address lines are an indication of this problem, which is easy to spot with the motherboard out of the case.
Schemes for battery backup of the CMOS settings abound, with the most common one being a soldered, rechargeable battery on the motherboard which can be replaced by an external battery mated to a four pin connector (normally one pin is cut away as a key). The second most common method involves a combination real time clock/battery which is socketed and tie-wrapped to the motherboard. These combination units are highly reliable and have expected liftimes greater then 5 years.
When replacing a battery of the first type with an external, you often have to move a jumper on a 3-pin block the motherboard from "internal" to "external". If no documentation is available, this jumper block is normally the one closest to the battery connection. It sometimes takes the form of a 2-pin block to be jumpered or left open.If several replacement batteries fail in days or weeks, you can try cutting a lead on the onboard battery, and re-mounting the motherboard to ensure that there are no electrical shorts on the bottom, or trying a different jumper in the undocumented case.
If the problem persists, you can either live with it, or throw out the motherboard, hopefully salvaging the CPU and memory.
Cache memory can be responsible for intermittent lockups, conflicts with software caching programs, and system lockups immediately after or during the boot process. The normal way to diagnose external cache problems is tell the system that no external cache is present in the advanced CMOS setup menu.
If the system functions properly, try to replace the single tag ram chip, before replacing the four or eight cache chips. The tag ram chip is located next to the cache chips and is normally faster by 5 or 10 nS.If the system hangs while you are trying to get to the setup menu, try replacing the main memory and running the motherboard of a different power supply before going to the effort of replacing the cache.
Some software caching programs, particularly those use by some of the older and off brand network operating systems, will not operate with external cache enabled. Try getting a software upgrade or live with the external cache disabled.
This is the on processor cache on 486 and newer CPUs'. If the internal cache needs to be disabled for the system to function normally, it's time to get a new CPU, because the performance will be down in the old XT/AT range.
Failures of main memory are the most common cause of intermittent lockups, especially when those lockups occur only in specific programs or only in the programs which are cognizant of extended memory.
The surest way to troubleshoot memory failures is to run a diagnostic program that does a slow memory check (the test should take at least a minute or two per megabyte).Most memory failures will be local to a single chip on a single SIMM. SIMMs should be reseated in their sockets and re-tested before being written off.
72pin SIMMS of capacity 4MB or higher are replacing 30pin SIMMs that were common in older (up through 486) systems. 72pin SIMMs are 32 bits wide, compared with 8 bits for 30pin SIMMS. Therefore, a 486 system requires only a single 72pin SIMM to function, while a Pentium requires two.
Memory within a bank on the motherboard (2 30pin SIMMS on 386SX, 4 or 8 30pin SIMMS on all higher machines) should be kept all the same type of SIMM, speed, and brand. The hobbyist or home user may be willing to gamble on changing a single SIMM, but in most cases, the whole bank should be changed. Old odd SIMMs can be used for troubleshooting, or can be used on caching controllers or other applications with 1 or 2 SIMM banks.
In some instances, inserting a wait state in the advanced CMOS setup will solve the problem, at least temporarily, and the system should then pass the diagnostic.
Older systems were built with DIP memory socketed or soldered to the motherboard. Systems with soldered memory aren't worth any effort, those with socketed memory may be revived by re-seating all of the chips. Bad chips can be exchanged one for one with chips of the same or faster speed, it's not necessary to replace the whole bank.
Most 16 bit extended or expanded memory cards will work in newer machines, some require software drivers, others need to have switches set specifying their start address and the total amount of memory in the computer. Many of the older boards held 2 or 3 MB of memory and can come in handy on an underpowered machine.
A backwards cable will eat the FAT table on a floppy, so system disks become non-bootable, and futher confuse the issue for a novice, since now the system won't boot with the cable on either way. Make sure the red line on the ribbon is on pin 1 or 2 on the controller card. When building a new machine or adding a second floppy drive, if the LED stays lit on the 3.5" drive from the moment the system powers up, the ribbon cable is backwards at the drive end, or has been forced on and missed two pins on one end or the other.
The best way to check is to disconnect the cable and look at the connector block for bent pins. The only fool-proof way to make the connection is to remove the drive, make the connection, and slide the drive in from the back.
The second most common problem on new machines, or machines that have been worked on, is the wrong drive type (i.e. 360K, 720K, 2.88M), or not installed be selected in the CMOS setup. A drive with the wrong CMOS type will often pass all hardware diagnostic tests and may even properly show the directory of the floppy disk, but will fail on extended reads or writes, often resulting in data loss. This problem may not be noticed on a new machine for months after delivery, and should always be the first item checked during telephone troubleshooting of drive problems.
The easiest field failure to diagnose is when the on-drive LED doesn't come on or the drive doesn't spin up or seek.Try changing the power cable to the drive and re-seating the ribbon cable on the drive and the controller card.
If the drive still fails to respond, the problem is the drive or the controller. The controller is tested during boot time and will normally produce a FDD/HDD controller failure message if bad.
The next most common floppy drive problem is mechanical failures. Knobs often strip on 5.25" floppies, a process which is accelerated by forcing the lever shut with no floppy in the drive. Pieces of labels can get stuck in either size of drive, and can normally be seen and pulled out with tweezers. The metal cover on the 3.5" floppy disks can come of the disk and get stuck in the drive or the sprint on the spring loaded door may pop off. Most of these problems will clear up with the removal of the foreign object.
Floppy drives are notoriously unreliable, particularly when being use in office environments that have a large mix of machines with different brands and drive densities.Most strange floppy drive behavior arises from reading and writing floppies from different machines and formatting floppy disks at lower then the maximum drive capacity.
As a rule of thumb, if a problem reading and writing a disk occurs on some machines and not others, the problem is with the disk. Keep in mind that the read/write heads on a low capacity drive are twice as wide as the heads on a high capacity drive and source twice the write current. Most high capacity drives cannot make this adjustment when formatting lower capacity disks, and therefore, the format procedure does not match the media, which is physically different for the high and low density disks.
Some fiscally conservative individuals attempt to recycle low density disks in high density drives by defeating the mechanical check. This is bad practice and failures involving these disks in no way imply a problem with the drive.
In cases where the drive fails to read or write a group of floppies that work normally in a sampling of other machines may indicate a true drive failure.
Again, the easiest diagnostic is to swap it out. Intermittent read/write failures may be due to the controller or even the motherboard, the former is easy to troubleshoot by swapping out the controller and the latter is very, very rare.
Bad chassis ground can also produce intermittent problems, refer to power supply section.
Modern IDE hard drives are among the more reliable system components, they should run for years, then fail with a whimper or a bang. Most of the problems that creep up with a hard drive are actually operating system problems.
Physical errors should be easy to spot with any decent diagnostic program that runs a variety of hard drive tests (including butterfly read). Factory low level or "rescue" formatters will scrub a drive and prepare it for FDISK no matter how bad the software problems get. The most common reasons for returning hard drives at burn-in are; excessive noise, failure to allow partitioning with FDISK, failure to remain FDISKed, and various incarnations of dead (doesn't spin up, doesn't seek, system reports HDD controller failure, etc.).
The most important thing to remember about working with IDE hard drives is to RECORD THE BIOS TRANSLATION PARAMETERS AT BUILD TIME. These parameters are sometimes incorporated in the drive label. SCSI drives are set up as not present in the CMOS setup and are operated through the controller BIOS. Read the manual. The only jumpers to worry about on IDE hard drives are the Master/Slave jumpers, which aren't always consistent even from the same manufacturer.
New systems come with an "Autodetect Hard Drive" option in the CMOS setup, which will restore the drive parameters automatically, and can be used to rediscover parameters for drives from older machines.Older hard drives are not worth repairing, due to the availability of faster, larger drives costing the same as the repair. The challenge with old hard drives is trying to recover data that was never backed up before recycling them as bookends.
Old drives that spin up but don't seek are often stuck in park.
Tapping on the drive cover with a screwdriver handle may unstick the heads and get the drive going long enough to get the data off.Drives that hum or display a lit LED and that don't spin up may be suffering from failure of the permanent lubrication.
Often moving the machine to a warm place or even putting it in direct sunlight may get the drive going temporarily.
Sometimes a drive appears to be functioning mechanically, but has had its master boot record so corrupted that disk utilities cannot access it.
If an identical IDE drive is available, try booting that drive and then moving the ribbon connector to the bad drive without powering down the machine. This may give the disk utility access to the data on the disk. As with all "live power" procedures, employ extreme caution and watch for falling screws!When attempting any of these last ditch recovery attempts, have your backup media (floppy, tape, or direct computer link) connected and ready, because it may not work a second time.
I just working on a new site covering upgrading and repairing laptop and notebook PC's. It also covers some laptop buying decisions. There aren't a whole lot of upgrades the average laptop user wants to take on themselves, because the plactic contruction of laptops makes it a hair raising experience for people who lack experience. However, memory upgrades are usually pretty easy, and replacing the hard drive is a common fix, since they fail at a much higher rate than desktop hard drives.
The first page I did for the new site is an illustrated guide to replacing a laptop hard drive. It consists of 10 photographs and step by step instructions for a Toshiba notebook with a hard drive that can be accessed through a simple hatch on the bottom. It's a tougher job when you have to crack the whole laptop open to get at the drive.
The vast majority of new systems are built with video cards that are at least downwardly compatible with VGA. When dealing with older TTL cards and pre-VGA high resolution cards, the problem is compounded as the monitor may be the only one of its' type available.
The best chance for trouble shooting video problems in obsolete systems is to use a switchable, dual connector video card capable of emulating all of the TTL standards. Some of the older multisync monitors are capable of displaying all of the modes from MDA up to SVGA. Older WYSIWYG cards and monitors may be repairable by the manufacturer or by a good repair service, but keep in mind that both the card and the monitor cost over $1000.00 each when new, and are highly proprietary.
Total failure of a video card will normally produce a beep code, and can be easily diagnosed by trading out the card.Often, the problem is a blown video memory chip, and this can be easily replaced, if it is socketed.
Always replace video memory chips in banks, as with system memory. On most cards with more than 256K, the second bank can be substituted for the first, and the first bank can be left out while testing the card.
When building a new machine, conflicts between cards may appear as video card failure, particularly conflicts between VGA and super IDE cards. High end communication cards for remote terminal support, and other cards requiring frame buffers below the 1 MB boundary may produce memory conflicts with the VGA frame buffer area (A000 to C000).
Frame buffers on these cards can be moved by switch settings or by a software utility or the EISA configuration in EISA machines.Some flaky video problems, such as mouse tracks being left on the screen, are due to the wrong video memory being installed on the card. This particular problem may not show up until the card is warm, and only in some applications.
There are several different flavors of video memory, the card manufacturer should be consulted.
An oscillating image or loss of a primary color may be due to the VGA card, but often as not it can be a monitor, connection or environmental problem.The most common cause for a shaky or oscillating image is the presence of an external magnetic field, such as the power supply for your inkjet, or another small transformer, in colose proximity to the monitor. Ocassionally, high current carrying lines in the walls can be the problem.
Failure of an application to display a field or text as on another system is usually due to the video driver being installed incorrectly or not at all. This problem is more likely when working at resolutions higher than standard VGA (640x480).
Some cards have a jumper for use with monochrome VGA monitors, others may have a 4 or 16 shade monochrome driver. All SVGA cards have a jumper or software utility for setting interlaced or non-interlaced operation, and compatibility with monitors supporting VESA modes.
Never set a card to VESA timing or non-interlaced mode unless you are sure the monitor can support it, or the monitor may be damaged.
The most common monitor problem is total failure, power status LED fails to come on. This can be due to something as simple as a blown fuse, or something serious as a popped CRT. Most out of warranty repairs of 14" and under monitors, cost more than half of the wholesale cost of the monitor new, and are backed by only a 30 or 90 day warranty. A new SVGA NI 14" monitor is currently about $200 in the mail order market. Monitors over 14" may well be worth repairing, but this must be decided on a case by case basis.
Radical changes in screen size or brightness may be compensated for by hidden pots, but this will normally require working on the monitor live with the cover off around lethal voltages. Larger monitors may also come with a de-gaussing switch, which may clear up some slow developing display problems.Loss of a primary color that can be attributed to the monitor electronics is one of the problems out of warranty repair may be sensible for.
About half the problems with new monitors or systems that have been moved prove to be connections or electrical environment. A partially mated connector on either end of the cable can result in loss of colors or sync. A bent pin inside the connector shell can cause any problem ranging from no display to a scrolling screen. Long cable extensions can result in diminished brightness and loss of focus on the monitor. Wavy images are usually due to monitors being located near transformers, air-conditioning units, and hidden power lines.
Troubleshooting these problems involves moving the system to another location, or showing that the failures coincide with the operation of the other equipment.Monitors that are placed close together will often produce scan line interference on one another. Increasing monitor separation by a few feet or changing their orientation with one another will usually clear up the problem.
DRIVE CONTROLLER AND I/O CARDS
New systems (Pentium and Pentium Pro) normally integrate all of the I/O functions and the PCI drive controllers on the motherboard. These are highly reliable, but can normally be disabled in the CMOS and replaced with PCI or ISA cards if they fail.
Most 386 and 486 systems were built with Super IDE cards which incorporate a IDE drive interface, dual floppy controller, 2 serial ports and 1 parallel port. The cards come jumper configured for COM1 on interrupt 4, COM2 on interrupt 3 and LPT1 on interrupt 7. The most common problem with these cards is not total failure, which the system will inform you of on boot up with a FDD/HDD controller failure message.
Intermittent problems are unfortunately fairly common, with hard drive boot problems leading the pack. Random system lockup while accessing the drives, or failure to consistently recognize a mouse or printer are also common problems. Some apparent SIDE failures can be attributed to conflicts with certain VGA cards.Conflicts with other interrupt driven cards are common, and should be resolved at build time or when upgrading systems.
SIDE cards are the least expensive components in the system, and should always be changed on field service calls if under suspicion.
SCSI controllers and EISA controllers are manufactured to higher quality standards and are generally reliable. Make sure that the BIOS on SCSI cards is the current version, these are upgraded on a regular basis.
VESA local bus controllers fall somewhere between SIDE and the more expensive controllers for reliability. Local bus controllers with hardware cache are often problematic, compatibility problems with software, physical memory errors, and cache bottle-necking are common problems in new configurations.
EISA controllers must be configured properly using the motherboard EISA utility and configuration files supplied by the controller manufacturer. SCSI bus termination must always be observed by terminating the devices on either end , where the controller counts as a device.
SCSI controllers with an external 25 pin connector should have the connector covered or taped over if not in use, to prevent accidental connection of a printer cable.
Systems using IDE disk drives and SCSI CD-ROM's or tape drives may boot somewhat slower that usual, and the controller BIOS may produce a message about the boot device that can be misinterpreted as an error.
Network card failure is easily diagnosed if it comes with diagnostics software or if you have an identical card to swap out. Nine out of ten physical link network problems will actually be caused by cabling, terminators, hubs, repeaters or misuse.
Network cards are interrupt driven, occupy I/O space and may employ memory mapped transfers and are therefore subject to conflicts with other cards if not configured correctly. Most newer cards come with diagnostic LEDS which indicate the activity of the card.The newest cards are controlled by an EEPROM, eliminating switch and jumper settings. If the configuration software refuses to work, there is probably an I/O conflict with another adpter. Remove all non-essential cards (everything except video and drive conroller) than try running the software again and make the necessary changes.
All network cards require some sort of driver to be installed when the network boots, and if the driver installs successfully, the card is probably functional. Note that the software driver will normally install with the incorrect interrupt specified, or with an interrupt conflict that may prevent reliable operation.
Some coax network cards come with available on-board terminators. These terminators should never be used because they cause a great deal of confusion if network nodes are ever added or rearranged.
When troubleshooting nodes on a twisted pair network, it's good to have a long spare cable (50 ft. or more) that can be run to the RJ-45 jack of a working unit or directly to the hub.
There are more possible options for network cabling and topology than there are types of cards. All bus type topologies require a proper terminator at each end of the bus. The terminator resistance must match the characteristic impedance of the cable with must be the correct impedance for the type of card.
Networks installed with the wrong type of cable may work for some time after installation, even consistently, until nodes are added to the network or the weather changes. Never assume that the correct cabling has been installed just because "it used to work".Without expensive equipment, the way to check the impedance of existing coaxial cabling is to pull a little out of the wall, or look in the crawl space or drop ceiling and read the casing.
Standard coaxial cables used in networking are RG58U (50 ohms), RG59U (93 ohms) and RG62U (75ohm). The current standard for color coding NC terminators is green for 50 ohms (ethernet) and white for 93 ohms (arcnet). Some other topologies use 75 ohm coax, which is often improperly substituted for either 50 or 93 ohm cable, since it will often limp by on smaller networks.
10BaseT networks utilize twisted pair cable with RJ45 connectors and require a concentrator, or hub. Cabling is usually straight through and uses only 4 wires of the eight available in a RJ45 jack (1,2,3 and 6).
The most common "in wall" network errors are using the wrong impediance cable on coax networks, or putting the ends on wrong with twisted pair. Proper twisted pair cabling will use two color coded pairs out of the four pairs available in the standard connector. It's OK to use all eight wires (four pairs) to make aligning the connector easier, but you should be able to see through the clear plastic that the 1-2 and 3-6 pairs are the same color coding, for example; solid blue and white with blue stripe for 1-2 and solid green and white with green stripe for 3-6. Cables not made this way might limp by, particularly if they're very short, but they're wrong!
As with coaxial cable networks, in case of failure, the cable and connectors should be the first item checked.
Unlike small coaxial networks, twisted pair is often already in place or is installed by a separate contractor a customer site. The only foolproof way of checking cable integrity is to set up two known working workstations and actually run the network, or a hardware level diagnostic supplied with the card. Intermittent network problems will most often be cause by intermittent hardware failure at the node or server, unrelated to the network. Problems can arise from cabling that is run to close to sources of intermittent electrical noise or to the segment length limits specified for the equipment. Temperature and humidity can also be factors.
There are a tremendous number of setup parameters on a modem, both hardware and software, that can prevent the modem from operating. Hardware setup for internal modems is done on the modem card, while external modems utalize an existing com port
Make sure that the phone line you are attempting to call out on is valid by checking it with a cheap telephone handset.Many business phone systems will not support plain modem cabling and will require a special switch or dedicated line.
The "Line" or "Wall" connection on the modem is for connection to the wall jack, the "Phone" connection is for reconnecting the telephone.
The software troubleshooting procedure for both internal and external modems is basically a two step process.
First, ensure that the com port address or number and interrupt are selected correctly in the software. You should be able to hear the modem attempting to dial out at this point.Second, if the modem is dialing out but not making the connection, make sure that you are using the correct parameters for the particular number you are calling, including baud rate, number of data bits, stop bits, parity etc.. The baud rate must be in the range of capability of the modem.
If the modem cleary picks up the phone to dial, resulting twenty or thirty seconds later in a recorded message from the phone company, you are probably attempting to tone dial on a pulse system. Try changing the modem setup to pulse and dial again.
If you are attempting to operate the modem on com ports 3 or 4, try re-installing it on 1 or 2, because some software packages will not work on 3 or 4 despite having them listed as valid options.
Internal modems tend to be more troublesome than external modems, both because a generally lower quality, and the need to remove them from the machine to change hardware settings. One of the more annoying tendencies of cheaper internal modems is to pick up RF interference from high clock speed systems or from high resolution video cards and produce a whistling tone on their piezoelectric speaker.
Relocating the card to another slot sometimes lowers the noise level, re-orienting the computer can help as the sound is highly directional.Another common problem is documentation that does not agree precisely with the modem. Documentation often covers the software also, and is not modified with every hardware change.
Use the diagnostic software, or the computers boot screen to confirm that the modem is locating itself where you think it is. Remember that most systems are shipping with an SIDE card that com ports 1 and 2 built in and enabled by default.
Multimedia Kits and Components
Multimedia kits, comprising a CD ROM, a sound card, speakers, a microphone and tons of software, are one of the more problematic upgrades to a PC. Interrupt and address conflicts are the usual culprits. Highly integrated sound cards may include unwanted CD controllers which must be disabled if these are IDE or SCSI devices connected directly to the motherboard or other controllers. The best approach to installing a multimedia upgrade kit is to bite the bullet and map out the currently used interrupts and adresses before beginning.
Normally open interrupts, if you haven't installed a network card or any other after peripheral controllers, are 5,10,11 and 12. 300 and 340 are usually the best bet for the address.
Getting movies and other true multimedia offerings to play involves far more software setup than hardware. Even if your multimedia kit includes MPEG playback, that doesn't mean that you are good to go with every CD you play or clip you download from the WWW. Most multimedia products use software codecs (COmpression DECompression) algorithims that are included with the product and installed by it, if not already on your system. Examples of common codecs are Intel's Indeo or Cinepak by SuperMac. These codecs are generally updated about once a year and are not always backwards compatible, so you need the right version for your application.
The most common problem with bad picture quality for both movies and still pictures is having a "low color" video driver selected for Windows. Even if you system came with a $300, 2MB PCI screming hot video adapter, it won't look like much with 256 colors selected, which is how the vast majority of systems are still shipped!
The more exotic the video adapter you have, the more problems you will have. In order to push up their benchmarks, "high end" video adapters cut corners on compatablility. The average shmo (you or I) is better off with a 1MB Trident card, between $50 to $70 for ISA, VESA or PCI.
|
|
|
||||