Sunday, October 24, 2010

Computer Hardware

Inside the Case

The Motherboard
CPU and Memory
Storage Devices
Peripheral Cards
External Peripherals

Important PC Repair Safety Tips
Tips to Stay Safe While Working On Your Computer
In addition to being an afternoon of great fun, PC repair can save you loads of time and money. No amount of fun, money or time is enough, though, to compromise your safety.
Keep these important tips in mind as you work inside your computer:
Remember to Flip the Switch
Always, always, always remember to turn the power off before servicing anything. This should always be your first step. Do not even open the computer case unless the power is turned off. Many computers have a number of lights inside that serve certain functions so check to see that no lights are on. If any are still on then the power is probably not completely off.
Many power supply units have a switch on the back, killing power to the device and ultimately the rest of your PC. If your PSU has one, be sure to turn it to the off position.
Unplug for Extra Safety
As a second precaution, it is wise to unplug the computer from the wall or power strip. If there was any doubt as to whether the computer was off before, it's settled now.
Avoid Smoke and Smells
See smoke coming from the power supply or inside the case or smell a burning or solder scent? If so:
1. Stop what you're doing immediately.
2. Unplug the computer from the wall.
3. Allow the PC to cool or discharge unplugged for at least 5 minutes.
Finally, if you know which device was generating the smoke or smell, remove and replace it as soon as you can. Don't try to repair a device that's been damaged to this extent, especially if it's a power supply.
Remove Hand Jewelry
An easy way to get electrocuted is to work around a high voltage device like a power supply with metal rings, watches, or bracelets on. Remove anything conductive from your hands before working inside your computer, especially if you're doing something like testing your power supply.
Avoid Capacitors
Capacitors are miniature electronic components contained in many of the parts inside a PC. Capacitors can store electric charge for a short while after the power is turned off so it's a wise decision to wait a few minutes after pulling the plug before working on your PC.
Never Service the Non-Serviceable
When you come across labels that say "No serviceable components inside" don't take it as a challenge or even a suggestion. This is a serious statement.
Some parts of a computer are just not meant to be repaired, even by most professional computer repair persons. You will usually see this warning on power supply units but you may also see them on monitors, hard drives, optical drives and other dangerous or highly sensitive components.

What is a Power Supply?:
The power supply's job is to convert the power provided from the outlet into usable power for the many parts inside the computer case.
The Power Supply is Also Known As:
PSU (power supply unit), power pack, power converter
Important Power Supply Facts:
Motherboards, cases and power supplies all come in different sizes called form factors. All three must be compatible to work properly together.
Power supplies are not typically user serviceable.For your safety, it's usually wise to never open a power supply unit.
Popular Power Supply Manufacturers:
CoolMax, Ultra, (Most power supplies come preinstalled in computer cases)
Power Supply Description:
The power supply is mounted just inside the back of the case.
The side facing outside the case has a male, three pronged port that a power cable, connected to a power source, plugs into. There is also often a power switch and a power supply voltage switch.
Large bundles of colored wires extend from the opposite side of the power supply into the computer. Connectors at the opposite ends of the wires connect to various components inside the computer. Some are specifically designed to plug in to the motherboard while others have connectors that fit into fans, floppy drives, hard drives, optical drives, and even some high powered video cards.
Power supplies are rated by wattage to show how much power they can provide to the computer. Since each computer part requires a certain amount of power to function properly, it's important to have a power supply that can provide the right amount. The very handy Journey Systems Power Supply Calculator tool can help you determine how much you need.
"How Do I Test the Power Supply in My Computer?"
Question: "How Do I Test the Power Supply in My Computer?"
Testing a power supply is an important step when troubleshooting many issues, most obviously when your computer is having trouble starting.
However, a failing power supply can often be the cause of problems you might not expect like random lockups, spontaneous reboots, and even some serious error messages.
Ask any computer repair professional and he or she will probably tell you that the power supply is the most common piece of hardware to fail in a computer.
In my experience, the power supply is very often the first thing to fail as a computer ages.
Answer: You can test a power supply yourself manually using a multimeter or you can purchase a power supply tester to perform an automatic PSU test.
Both methods are equally effective ways of testing a power supply so which one you choose is completely up to you.
Here's some more information on how to test your power supply with each of these methods and some help deciding which method is best for you:
Method #1: Test a Power Supply Manually with a Multimeter
Advantages of a manual PSU test:
• The only tools needed are a screwdriver and a multimeter, both of which you likely already have. If you don't own a multimeter, you can usually find a basic one at any major retailer for around Rs.1,000 or you can find one online if you don't mind waiting a few days.
• Assuming you have a multimeter and screwdriver, you can test your power supply right now following the directions above.
Disadvantages of a manual PSU test:
• It's manual! It is going to take a little work on your part to thoroughly test your power supply.
• Testing a PSU manually can be dangerous if you're not very, very careful. See my warning at the bottom of the page for more information.
Method #2: Test a Power Supply Using a Power Supply Tester
Note: The instructions linked to above are specific to the Coolmax PS-224 ATX Power Supply Tester but the general idea applies to nearly any tester you choose to purchase.
Advantages of using a power supply tester:
• It's automatic! Power supply testers were invented because manual tests are manual and introduce human error. The results of a PSU test with a power supply tester unit is more conclusive.
• Testing a power supply with a power supply tester is a safer than testing one manually. A power supply tester lets you stay a bit more removed from the electricity than with a multimeter test.

Find and Buy a Power Supply Tester
Disadvantages of using a power supply tester:
• Chances are you don't have a power supply tester so you'll have to buy one. Depending on your choice of tester, you're probably looking to spend from around Rs.500 to Rs.4,000.
• Again, you probably don't have a power supply tester, meaning that you'll have to order one and wait until it shows up before you'll be able to test your power supply. That could mean that you live with a major computer problem longer than you'd like.
Extremely Important: Take great, great care when testing a power supply, especially if you've chosen to test it manually. Both methods above involve working with a high voltage power supply while it's plugged in. If you're not extremely careful you could electrocute yourself and/or damage your computer. I don't mention this to frighten you - testing a power supply is a common troubleshooting step and can be done safely if you exercise common sense and follow directions exactly. Just please be careful when doing so.
Did your power supply fail a test?
Replace the power supply. That's right, just replace it, even if it's partially working.
It is never a safe idea to fix one yourself. If you insist on having your PSU repaired rather than replaced then please seek the assistance of a professional repair person.
Having Problems Testing a Power Supply?
Need some help interpreting a result from your power supply test? Let a community of computer support enthusiasts help out! Post in the PC Support Forum about what kinds of problems you're having testing your power supply and we'll try to help out.

How To Troubleshoot a Computer That Won't Turn On
t's a dreadful way to start a day - you press the power button on your computer and nothing happens. Few computer problems are more frustrating than when your computer won't boot.
There are many reasons why a computer won't turn on and often very few clues about what might be the problem. The only symptom is usually the simple fact that "nothing works" which isn't much to go on.
Add to this the fact that whatever is wrong could be an expensive part of your PC to replace - like the motherboard or CPU.
Do not fear because all may not be lost! Follow these steps to determine why your computer won't turn on.
Difficulty: Average
Time Required: Anywhere from 10 minutes to a few hours or more depending on why the computer won't turn on
Here's How:
1. Try to relax! There's a good chance you can figure out exactly why your computer won't start and then get it back up and running.
I don't usually start a troubleshooting guide with the same advice a therapist might give her client, but when faced with a computer that won't start most people tend to panic, worried that all the data on their PC is gone forever.
It's true that the most common reason a computer won't start is because a piece of hardware has failed or is causing a problem but that hardware isn't usually a hard drive. Your data is probably safe - just not accessible.
2. Computer shows no sign of power at all. Try these steps if your computer will not turn on and is showing no sign at all of receiving power - no fans running and no lights on the computer case.
Important: You may or may not see a light on the back of your PC depending on the kind of power supply you have and the exact cause of the problem.
Note: Don't worry about the monitor yet. If the computer is not turning on because of a power issue then the monitor certainly can't display anything from the computer. Your monitor light will likely be amber/yellow if your computer has stopped sending information to it.
3. Computer turns on for a few seconds and then turns off. Follow these steps if, when you turn your computer on, it promptly powers back off.
You'll probably hear the fans inside your computer turn on, see the lights on the front of your computer turn on or flash, and then it will all stop - always before the boot process is complete. You may or may not also hear beeping coming from inside your PC.
Note: As in the previous scenario, don't worry about what state your monitor is in. You may have a monitor issue as well but it's not possible to troubleshoot it quite yet.
4. Computer turns on but nothing shows on screen. If your computer seems to be receiving power after turning it on but you don't see anything on your monitor, try these troubleshooting steps.
In these situations, the power lights will stay on, you'll likely hear the fans inside your PC running, and you may or may not hear one or more beeps coming from the computer.
This situation is probably the most common in my experience working with computers that won't start. Unfortunately it's also one of the most difficult to troubleshoot.
5. Computer turns on but stops booting during the POST. Use this guide when your computer powers on, shows at least some information on the monitor, but then stops for any reason during the Power On Self Test.
Use this troubleshooting guide primarily if you receive a BIOS error message during the POST but also if your PC locks up during the POST without an on-screen message.
Important: If you're having an issue during the loading of the operating system, which occurs after the Power On Self Test is complete, see Step 6.
6. Computer turns on but an error message prevents the operating system from loading completely. If your computer begins to load Windows but then stops booting and displays an error message, you're best bet is to troubleshoot the problem based on the specific error message.

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