Buat masa ini Microsoft akan menjalinkan usahasama dengan rakan kongsi di negara ini seperti Intel, Dell, HP, Toshiba, Lenovo dan Asus dalam membangunkan sistem operasi.
Sistem operasi Windows terbaru
Saturday, November 7, 2009
TIDAK lama lagi pengguna komputer boleh menggunakan perisian Microsoft Windows terbaru menggantikan Windows Vista dan XP. Bagi meningkatkan lagi prestasi pemprosesan komputer, Microsoft melancarkan perisian terkini Window 7 minggu lepas.
How to Solder
Tuesday, October 13, 2009
First a few safety precautions:
If you are unlucky (or careless!) enough to burn yourself please read the First Aid section.
Preparing the soldering iron:
You are now ready to start soldering:
If you are unlucky (or careless!) enough to burn yourself please read the First Aid section.
Using a heat sink
Some components, such as transistors, can be damaged by heat when soldering so if you are not an expert it is wise to use a heat sink clipped to the lead between the joint and the component body. You can buy a special tool, but a standard crocodile clip works just as well and is cheaper.
- Never touch the element or tip of the soldering iron. They are very hot (about 400°C) and will give you a nasty burn.
- Take great care to avoid touching the mains flex with the tip of the iron. The iron should have a heatproof flex for extra protection. An ordinary plastic flex will melt immediately if touched by a hot iron and there is a serious risk of burns and electric shock.
- Always return the soldering iron to its stand when not in use. Never put it down on your workbench, even for a moment!
- Work in a well-ventilated area. The smoke formed as you melt solder is mostly from the flux and quite irritating. Avoid breathing it by keeping you head to the side of, not above, your work.
- Wash your hands after using solder. Solder contains lead which is a poisonous metal.
If you are unlucky (or careless!) enough to burn yourself please read the First Aid section.
Preparing the soldering iron:
- Place the soldering iron in its stand and plug in. The iron will take a few minutes to reach its operating temperature of about 400°C.
- Dampen the sponge in the stand. The best way to do this is to lift it out the stand and hold it under a cold tap for a moment, then squeeze to remove excess water. It should be damp, not dripping wet.
- Wait a few minutes for the soldering iron to warm up. You can check if it is ready by trying to melt a little solder on the tip.
- Wipe the tip of the iron on the damp sponge. This will clean the tip.
- Melt a little solder on the tip of the iron. This is called 'tinning' and it will help the heat to flow from the iron's tip to the joint. It only needs to be done when you plug in the iron, and occasionally while soldering if you need to wipe the tip clean on the sponge.
You are now ready to start soldering:
- Hold the soldering iron like a pen, near the base of the handle. Imagine you are going to write your name! Remember to never touch the hot element or tip.
- Touch the soldering iron onto the joint to be made. Make sure it touches both the component lead and the track. Hold the tip there for a few seconds and...
- Feed a little solder onto the joint. It should flow smoothly onto the lead and track to form a volcano shape as shown in the diagram. Apply the solder to the joint, not the iron.
- Remove the solder, then the iron, while keeping the joint still. Allow the joint a few seconds to cool before you move the circuit board.
- Inspect the joint closely. It should look shiny and have a 'volcano' shape. If not, you will need to reheat it and feed in a little more solder. This time ensure that both the lead and track are heated fully before applying solder.
If you are unlucky (or careless!) enough to burn yourself please read the First Aid section.
Using a heat sink
Some components, such as transistors, can be damaged by heat when soldering so if you are not an expert it is wise to use a heat sink clipped to the lead between the joint and the component body. You can buy a special tool, but a standard crocodile clip works just as well and is cheaper.
Test Your PSU's Voltage Rails With A Multimeter
The best way to get the most accurate readings from your PSU is to use a multimeter. Hardware monitors, and BIOS will not give you TRUE real voltages on those 3 main voltage lines. Many people still rely on means of software, such as MBM, Speedfan, and the BIOS, but these are all very unreliable.
More about software/bios readings on the rails:
In order for the software to read your PSU's rails, or lines of voltage required to run your computer properly, a chip on your motherboard needs to read these voltages. There is usually resistance between the PSU and the monitoring chip on the motherboard. According to a motherboard monitoring software, an 12-volt Rail can be way under spec. You want your voltage to be within 4%. So you want your 12-volt rail to be within 11.52 to 12.48 during load. This means when you are running your CPU at 100% you do not want to drop below 11.52 or you may experience stability problems including but not limited to system restarts and Windows crashes. For the 5-volt rail, you want it to be within 4.8 to 5.2 to be within the 4% range. As for the 3.3 volt rail, you want it to be within 3.17 to 3.43.
What are RAILs?
Rails are the above mentioned voltage lines coming from your PSU to your motherboard and devices in your motherboard. The 3.3-volt and 5-volt generally power the devices like the motherboard, PCI slots, AGP slot, etc. The 12-volt is usually used for things with motors like the hard drives, CD-ROM, fans, etc.
What's a multimeter / voltmeter?
A multimeter is an electronic measuring instrument that combines several functions in one unit. The most basic instruments include an ammeter, voltmeter, and ohmmeter.
A multimeter can be a handheld device useful for basic fault finding and field service work or a bench instrument which can measure to seven or eight and a half digits of accuracy. Such an instrument will commonly be found in a calibration lab and can be used to characterize resistance and voltage standards or adjust and verify the performance of multi-function calibrators.
The 1st pic is a Digital Multimeter, and the 2nd is an Analog Multimeter:
Preparations:
CAUTION: This test involves using probes with the computer ON. Please only do this if you feel competent enough to be dealing with electricity. If you short rails, you could risk damaging the PSU and possibly your components. I cannot be held responsible if something goes wrong, this is merely a guide. If you feel any concern, please post BEFORE doing this, and we will be glad to help.
If you are afraid of doing such a thing and you are not sure what any of this guide means, I encourage you to NOT do this. Electricity is dangerous and can kill you in a heartbeat. Remember this is only a thread, what informs you, on how to do this. If you aren't sure of what you doing, DON'T DO IT.
Firstly, you will have to set up the multimeter to read the voltages you will be measuring. You should be able to move a dial on the multimeter. You want to move this to the number 20 (like this), in the section which relates to DC voltage. This is usually represented by THIS symbol.
Put The Black probe into the 'COM' plug on the multimeter. The Red probe should be placed in voltage detection plug.
DO NOT insert the probe into the 'current detection' plug, which on cheaper MM's usually has a '10A max or 10ADC' Label.
More preparations:
The first thing you want to do is download Prime95. Download it here. Prime95 is used to put your system at full load. You want your system at full load when checking your voltages to ensure your PSU is up to spec. The whole point is to make sure your PSU can handle what your system asks of it. This can only be done by stressing your system during the voltage test.
Now you want to shut down your system and then open the side so you have access to your AUS and a Molex plug. How to test with the Molex plug is discussed later in the guide. Lay your computer on it's side during this test or this will be more difficult than necessary.
Locate a free 4 pin Molex Connector, although you can test the back of molex connectors, if you have non spare, it just might be a bit more akward.
Locate the AUX connector:
And pull these into an area free from any clutter, so they are accessible for the probes on your multimeter. This may be a good time to do some cable rearrangement.
Measuring the VOLTAGEs:
Time to start. You want to observe these 3 voltages in all states. So you will have to set up the probes BEFORE you turn the PC on, because you want to observe the voltages for.
* POST
* Boot
* Windows Start up
* System at Idle
* System at Load
* Shutting Down
That is the problem with most PSU measuring guides, they test the PSU externally, with only the load of maybe a few fans, which does NOT give any real kind of indication on how the PSU copes powering a computer. So, set up each of these measuring, and observe/record the voltages at each stage as listed above. Ideally, they should not go above or below the rated voltage, though no component is perfect, which is why there is an ATX specification, which sets parameters for each voltage.
It is my opinion though, that any PSU which falls close to the min ATX spec, needs replacing.
Another Purpose of these rail tests are to find out how much your rails fluctuate, and if they do a lot, even if they stay within ATX spec, id suggest replacement. Clean, Stable voltage is just as Important as enough Voltage.
STEP 1: Measuring The 12V Rail
For this you just need the 4-pin Molex. Insert the red probe into the yellow 12v connector, and the black probe into any black Ground connector on the Molex:
STEP 2: Measuring The 5V Rail
For this you just need again the 4-pin Molex. Insert the red probe into the red 5v connector, and the black probe into any black Ground connector on the molex:
STEP 3: Measuring The 3.3V Rail
For this you will need the a.> AUX Connector Only, OR b.> a combination of the AUX and 4-pin Molex.
Insert the red probe into either one of the two orange 3.3v connectors on the AUX connector
Insert the black probe into any of the black ground connectors on the AUX connector, or the 4-pin Molex connector.
Note: Some people may struggle to insert the probe into the aux connector like is pictured, but you can also test the rail via the back of the connector.
method1: Using Just AUX Connector:
method2: Using AUX and 4-pin Molex:
Another way of testing this is in the DriverHeaven's Guide, their method is involving the 20pin Motherboard plug and a Molex Plug.
method3: Using 20pin plug:
More info about using the 20pin method, relating that you can measure the 3.3v,5v,12v from that single 20pin plug:
Orange, Red and then Yellow. 3.3, 5 and 12 volts respectively.
Make sure you have the multimeter on the correct setting if it is not auto-switching. I put mine on DC or Direct Current and on the "20" volt setting where you will get the most accurate results in this range.
Between each Rail testing you should have the appropriate voltage range on the multimeter. For example if you are testing the 12-volt rail (Yellow wire) then your voltage should be in the 12 volt range. Double check and make sure you have your multimeter.
More about software/bios readings on the rails:
In order for the software to read your PSU's rails, or lines of voltage required to run your computer properly, a chip on your motherboard needs to read these voltages. There is usually resistance between the PSU and the monitoring chip on the motherboard. According to a motherboard monitoring software, an 12-volt Rail can be way under spec. You want your voltage to be within 4%. So you want your 12-volt rail to be within 11.52 to 12.48 during load. This means when you are running your CPU at 100% you do not want to drop below 11.52 or you may experience stability problems including but not limited to system restarts and Windows crashes. For the 5-volt rail, you want it to be within 4.8 to 5.2 to be within the 4% range. As for the 3.3 volt rail, you want it to be within 3.17 to 3.43.
What are RAILs?
Rails are the above mentioned voltage lines coming from your PSU to your motherboard and devices in your motherboard. The 3.3-volt and 5-volt generally power the devices like the motherboard, PCI slots, AGP slot, etc. The 12-volt is usually used for things with motors like the hard drives, CD-ROM, fans, etc.
What's a multimeter / voltmeter?
A multimeter is an electronic measuring instrument that combines several functions in one unit. The most basic instruments include an ammeter, voltmeter, and ohmmeter.
A multimeter can be a handheld device useful for basic fault finding and field service work or a bench instrument which can measure to seven or eight and a half digits of accuracy. Such an instrument will commonly be found in a calibration lab and can be used to characterize resistance and voltage standards or adjust and verify the performance of multi-function calibrators.
The 1st pic is a Digital Multimeter, and the 2nd is an Analog Multimeter:
Preparations:
CAUTION: This test involves using probes with the computer ON. Please only do this if you feel competent enough to be dealing with electricity. If you short rails, you could risk damaging the PSU and possibly your components. I cannot be held responsible if something goes wrong, this is merely a guide. If you feel any concern, please post BEFORE doing this, and we will be glad to help.
If you are afraid of doing such a thing and you are not sure what any of this guide means, I encourage you to NOT do this. Electricity is dangerous and can kill you in a heartbeat. Remember this is only a thread, what informs you, on how to do this. If you aren't sure of what you doing, DON'T DO IT.
Firstly, you will have to set up the multimeter to read the voltages you will be measuring. You should be able to move a dial on the multimeter. You want to move this to the number 20 (like this), in the section which relates to DC voltage. This is usually represented by THIS symbol.
Put The Black probe into the 'COM' plug on the multimeter. The Red probe should be placed in voltage detection plug.
DO NOT insert the probe into the 'current detection' plug, which on cheaper MM's usually has a '10A max or 10ADC' Label.
More preparations:
The first thing you want to do is download Prime95. Download it here. Prime95 is used to put your system at full load. You want your system at full load when checking your voltages to ensure your PSU is up to spec. The whole point is to make sure your PSU can handle what your system asks of it. This can only be done by stressing your system during the voltage test.
Now you want to shut down your system and then open the side so you have access to your AUS and a Molex plug. How to test with the Molex plug is discussed later in the guide. Lay your computer on it's side during this test or this will be more difficult than necessary.
Locate a free 4 pin Molex Connector, although you can test the back of molex connectors, if you have non spare, it just might be a bit more akward.
Locate the AUX connector:
And pull these into an area free from any clutter, so they are accessible for the probes on your multimeter. This may be a good time to do some cable rearrangement.
Measuring the VOLTAGEs:
Time to start. You want to observe these 3 voltages in all states. So you will have to set up the probes BEFORE you turn the PC on, because you want to observe the voltages for.
* POST
* Boot
* Windows Start up
* System at Idle
* System at Load
* Shutting Down
That is the problem with most PSU measuring guides, they test the PSU externally, with only the load of maybe a few fans, which does NOT give any real kind of indication on how the PSU copes powering a computer. So, set up each of these measuring, and observe/record the voltages at each stage as listed above. Ideally, they should not go above or below the rated voltage, though no component is perfect, which is why there is an ATX specification, which sets parameters for each voltage.
It is my opinion though, that any PSU which falls close to the min ATX spec, needs replacing.
Another Purpose of these rail tests are to find out how much your rails fluctuate, and if they do a lot, even if they stay within ATX spec, id suggest replacement. Clean, Stable voltage is just as Important as enough Voltage.
STEP 1: Measuring The 12V Rail
For this you just need the 4-pin Molex. Insert the red probe into the yellow 12v connector, and the black probe into any black Ground connector on the Molex:
STEP 2: Measuring The 5V Rail
For this you just need again the 4-pin Molex. Insert the red probe into the red 5v connector, and the black probe into any black Ground connector on the molex:
STEP 3: Measuring The 3.3V Rail
For this you will need the a.> AUX Connector Only, OR b.> a combination of the AUX and 4-pin Molex.
Insert the red probe into either one of the two orange 3.3v connectors on the AUX connector
Insert the black probe into any of the black ground connectors on the AUX connector, or the 4-pin Molex connector.
Note: Some people may struggle to insert the probe into the aux connector like is pictured, but you can also test the rail via the back of the connector.
method1: Using Just AUX Connector:
method2: Using AUX and 4-pin Molex:
Another way of testing this is in the DriverHeaven's Guide, their method is involving the 20pin Motherboard plug and a Molex Plug.
method3: Using 20pin plug:
More info about using the 20pin method, relating that you can measure the 3.3v,5v,12v from that single 20pin plug:
Orange, Red and then Yellow. 3.3, 5 and 12 volts respectively.
Make sure you have the multimeter on the correct setting if it is not auto-switching. I put mine on DC or Direct Current and on the "20" volt setting where you will get the most accurate results in this range.
Between each Rail testing you should have the appropriate voltage range on the multimeter. For example if you are testing the 12-volt rail (Yellow wire) then your voltage should be in the 12 volt range. Double check and make sure you have your multimeter.
Manually Test a Power Supply With a Multimeter
Read Important PC Repair Safety Tips. Manually testing a power supply involves working closely with high voltage electricity. Important: Do not skip this step! Safety should be your primary concern during a power supply test and there are several points you should be aware of before starting this process.Open your case. In short, this involves turning off the computer, removing the power cable and unplugging anything else connecting to the outside of your computer. To make testing your power supply easier, you should also move your disconnected and open case somewhere easy to work like on a table or other flat, non-static surface.
Unplug the power connectors from each and every internal device. Tip: An easy way to confirm that each power connector is unplugged is to work from the bundle of power cables coming from the power supply inside the PC. Each group of wires should terminate to one or more power connectors. Note: There is no need to remove the actual power supply unit from the computer nor is there any reason to disconnect any data cables or other cables not originating from the power supply.
Group all of the power cables and connectors together for easy testing. As you're organizing the power cables, I highly recommend rerouting them and pulling them as far away from the computer case as possible. This will make it as easy as possible to test the power supply connections.
Short out pins 15 and 16 on the 24-pin motherboard power connector with a small piece of wire. You'll probably need to take a look at the ATX 24 pin 12V Power Supply Pinout table to determine the locations of these two pins.
Confirm that the power supply voltage switch located on the power supply is properly set for your country. Note: In the US, the voltage should be set to 110V/115V. Check the Foreign Electricity Guide for voltage settings in other countries.
Plug the PSU into a live outlet and flip the switch on the back of the power supply. Assuming that the power supply is at least minimally functional and that you've properly shorted the pins in Step 5, you should hear the fan begin to run. Important: Just because the fan is running does not mean that your power supply is supplying power to your devices properly. You'll need to continue testing to confirm that. Note: Some power supplies do not have a switch on the back of the unit. If the PSU you're testing does not, the fan should begin to run immediately after plugging the unit into the wall.
Turn on your multimeter and turn the dial to the VDC (Volts DC) setting. Note: If the multimeter you're using does not have an auto-ranging feature, set the range to 10.00V.
First we'll test the 24 pin motherboard power connector: Connect the negative probe on the multimeter (black) to any ground wired pin and connect the positive probe (red) to the first power line you want to test. The 24 pin main power connector has +3.3 VDC, +5 VDC, -5 VDC (optional), +12 VDC, and -12 VDC lines across multiple pins. You'll need to reference the ATX 24 pin 12V Power Supply Pinout for the locations of these pins. I recommend testing every pin on the 24 pin connector that carries a voltage. This will confirm that each line is supplying the proper voltage and that each pin is properly terminated.
Document the number that the multimeter shows for each voltage tested and confirm that the reported voltage is within approved tolerance. You can reference Power Supply Voltage Tolerances for a list of proper ranges for each voltage. Are any voltages outside the approved tolerance? If yes, replace the power supply. If all voltages are within tolerance, your power supply is not defective. Important: If your power supply passes your tests, I highly recommend you continue testing to confirm that it can operate properly under a load. If you're not interested in testing your PSU further, skip to Step 15.
Turn off the switch on the back of the power supply and unplug it from the wall.
Reconnect all of your internal devices to power. Also, don't forget to remove the short you created in Step 5 before plugging back in the 24 pin motherboard power connector. Note: The biggest mistake made at this point is forgetting to plug everything back in. Aside from the main power connector to the motherboard, don't forget to provide power to your hard drive(s), optical drive(s), and floppy drive. Some motherboards require an additional 4, 6, or 8 pin power connector and some video cards need dedicated power too.
Plug in your power supply, flip the switch on the back if you have one, and then turn on your computer as you normally do with the power switch on the front of the PC. Note: Yes, you'll be running your computer with the case cover removed which is perfectly safe as long as you're careful. Note: It's not common, but if your PC does not turn on with the cover removed, you may have to move the appropriate jumper on the motherboard to allow this. Your computer or motherboard manual should explain how to do this.
Repeat Step 9 and Step 10, testing and documenting the voltages for other power connectors like the 4 pin peripheral power connector, the 15 pin SATA power connector, and the 4 pin floppy power connector. Note: The pinouts necessary to test these power connectors with a multimeter can be found in my ATX Power Supply Pinout Tables list. Just as with the 24 pin motherboard power connector, if any voltages fall too far outside the listed voltage (see Power Supply Voltage Tolerances) you should replace the power supply.
Once your testing is complete, turn off and unplug the PC and then put the cover back on the case. Assuming your power supply tested good or you've replaced your power supply with a new one, you can now turn your computer back on and/or continue troubleshooting the problem you are having.
| Pin | Name | Color | Description |
|---|---|---|---|
| 1 | +3.3V | Orange | +3.3 VDC |
| 2 | +3.3V | Orange | +3.3 VDC |
| 3 | COM | Black | Ground |
| 4 | +5V | Red | +5 VDC |
| 5 | COM | Black | Ground |
| 6 | +5V | Red | +5 VDC |
| 7 | COM | Black | Ground |
| 8 | PWR_ON | Gray | Power Good |
| 9 | +5VSB | Purple | +5 VDC Standby |
| 10 | +12V1 | Yellow | +12 VDC |
| 11 | +12V1 | Yellow | +12 VDC |
| 12 | +3.3V | Orange | +3.3 VDC |
| 13 | +3.3V | Orange | +3.3 VDC |
| 14 | -12V | Blue | -12 VDC |
| 15 | COM | Black | Ground |
| 16 | PS_ON# | Green | Power Supply On |
| 17 | COM | Black | Ground |
| 18 | COM | Black | Ground |
| 19 | COM | Black | Ground |
| 20 | NC | White | -5 VDC (Optional - Removed in ATX12V v2.01) |
| 21 | +5V | Red | +5 VDC |
| 22 | +5V | Red | +5 VDC |
| 23 | +5V | Red | +5 VDC |
| 24 | COM | Black | Ground |
Troubleshooting An Ailing Power Supply
The Power Supply convert's your regular household current into low DC voltage used by the computer. When this component fails,there is simply no activity going on wih your computer.Remember to do the
easy troubleshooting first.Inspect the Power Supply
for any damage.Double-Check all connections.
Learning how to check your power supply and how to replace it when needed can be a life saver if you're a computer buff or in business with the trusted PC.Don't take for granted the sinple pleasure of turning on your PC and everything works just fine.
We turned on one of our computer's recently and if about one hour,it just re-booted itself.And it continued doing so about 10 times a day until we found out the power supply was the culprit.Things to look for when your power supply is going bad or just dies on you are the following....
NO POWER TO THE COMPUTER
Here you must first check the wall outlet for power by connecting another device such as a radio or lamp to be sure power is present.If the computer is connected through a surge protector,check it
as well.
If the wall out has power,check the power cable going to the PC to see if AC voltage is making its way to the system unit.Do this with the use of a multimeter.If there is power,you will have to open the computer and check for power from the power supply to the motherboard.When using a multimeter to check voltage,be sure you have a good ground for the black lead of the multimeter.
RE-BOOTING PROBLEMS
One main problem you may face with an ailing Power Supply is that it may re-boot the computer without any warning.All information is lost and it seems as though this happens at the worst possible time.Booting errors when the computer first start's up is another indicator of this component going on the blink.
POWER DISTRIBUTION PROBLEMS
When the power supply begins to fail,you may receive power at one device and not another.For example,the Hard Drive may receive power but the CDROM Drive has nothing at all.
Another headache with would cause re-booting is the intermittent power going to the drives or the motherboard itself.Follow the steps below to check your power supply should you experience some of the above problems.
CHECKING THE POWER SUPPLY
If the wall outlet,and the power cord are good,as well as the connection at the motherboard is secure.Then you may have to face the fact that the power supply itself is bad.If you have a Multimeter you can test the power supply output before purchasing a new one.Simply follow these steps.
Turn off the PC,but do not unplug it,open the system unit.Set the multimeter to read DC volts in the next range higher than 12 volts.Locate a power connector similair to the hard drive,or floppy drive connector that is unused and turn on the PC.You can also unplug a drive connector and use it as well.Turn on the PC and insert the BLACK probe into the power connector on one of the BLACK wires.Touch the RED probe to the YELLOW wire onthe power connector.
The multimeter reading should be +12 volts.Now touch the RED probe to the RED wire and the reading should be +5 volts.If no readings or different readings occured,you,ll have to replace the power supply.If the readings were correct,you should check the P8 or P9 connectors at the motherboard.These connectors may also be named P4 and P5.To check these connectors,perform the following...
Insert the BLACK probe into P8 at one of the BLACK wires.Insert the RED probe into the P8 connector at the RED wire.The readingon the multimeter should be +5 volts
Check the power going to the Motherboard connections by inserting the RED probe into P8 at the YELLOW wire and you should get +12 volts.Leave the BLACK wire touching the black wire at the P8 connector.Check the BLUE wire and the reading should be a -12 volts.
Now move the BLACK probe to the BLACK wire on the P9
connector.Test the WHITE wire by inserting the RED probe and the reading should be -5 volts.Check the RED wires on the P9 connector and you should get +5 volts on each red wire.You won,t get exactly 5
or 12 volts but the readings will be very close,such as 5.02 volts.
If the Power Supply is a couple of volts off,in either direction,such
as when the RED wire should be reading -5 volts but it reads -8
volts,or if there are no readings,replace the power supply.
DO NOT remove the power supply from the system unit case when performing these tests.DO NOT perform these tests if you do not feel comfortable.Be sure to remove any and all electrical static build-up from your clothes and body BEFORE touching any parts inside the system unit.And NEVER open the power supply case for any reason,since high voltage may be present.
easy troubleshooting first.Inspect the Power Supply
for any damage.Double-Check all connections.
Learning how to check your power supply and how to replace it when needed can be a life saver if you're a computer buff or in business with the trusted PC.Don't take for granted the sinple pleasure of turning on your PC and everything works just fine.
We turned on one of our computer's recently and if about one hour,it just re-booted itself.And it continued doing so about 10 times a day until we found out the power supply was the culprit.Things to look for when your power supply is going bad or just dies on you are the following....
NO POWER TO THE COMPUTER
Here you must first check the wall outlet for power by connecting another device such as a radio or lamp to be sure power is present.If the computer is connected through a surge protector,check it
as well.
If the wall out has power,check the power cable going to the PC to see if AC voltage is making its way to the system unit.Do this with the use of a multimeter.If there is power,you will have to open the computer and check for power from the power supply to the motherboard.When using a multimeter to check voltage,be sure you have a good ground for the black lead of the multimeter.
RE-BOOTING PROBLEMS
One main problem you may face with an ailing Power Supply is that it may re-boot the computer without any warning.All information is lost and it seems as though this happens at the worst possible time.Booting errors when the computer first start's up is another indicator of this component going on the blink.
POWER DISTRIBUTION PROBLEMS
When the power supply begins to fail,you may receive power at one device and not another.For example,the Hard Drive may receive power but the CDROM Drive has nothing at all.
Another headache with would cause re-booting is the intermittent power going to the drives or the motherboard itself.Follow the steps below to check your power supply should you experience some of the above problems.
CHECKING THE POWER SUPPLY
If the wall outlet,and the power cord are good,as well as the connection at the motherboard is secure.Then you may have to face the fact that the power supply itself is bad.If you have a Multimeter you can test the power supply output before purchasing a new one.Simply follow these steps.
Turn off the PC,but do not unplug it,open the system unit.Set the multimeter to read DC volts in the next range higher than 12 volts.Locate a power connector similair to the hard drive,or floppy drive connector that is unused and turn on the PC.You can also unplug a drive connector and use it as well.Turn on the PC and insert the BLACK probe into the power connector on one of the BLACK wires.Touch the RED probe to the YELLOW wire onthe power connector.
The multimeter reading should be +12 volts.Now touch the RED probe to the RED wire and the reading should be +5 volts.If no readings or different readings occured,you,ll have to replace the power supply.If the readings were correct,you should check the P8 or P9 connectors at the motherboard.These connectors may also be named P4 and P5.To check these connectors,perform the following...
Insert the BLACK probe into P8 at one of the BLACK wires.Insert the RED probe into the P8 connector at the RED wire.The readingon the multimeter should be +5 volts
Check the power going to the Motherboard connections by inserting the RED probe into P8 at the YELLOW wire and you should get +12 volts.Leave the BLACK wire touching the black wire at the P8 connector.Check the BLUE wire and the reading should be a -12 volts.
Now move the BLACK probe to the BLACK wire on the P9
connector.Test the WHITE wire by inserting the RED probe and the reading should be -5 volts.Check the RED wires on the P9 connector and you should get +5 volts on each red wire.You won,t get exactly 5
or 12 volts but the readings will be very close,such as 5.02 volts.
If the Power Supply is a couple of volts off,in either direction,such
as when the RED wire should be reading -5 volts but it reads -8
volts,or if there are no readings,replace the power supply.
DO NOT remove the power supply from the system unit case when performing these tests.DO NOT perform these tests if you do not feel comfortable.Be sure to remove any and all electrical static build-up from your clothes and body BEFORE touching any parts inside the system unit.And NEVER open the power supply case for any reason,since high voltage may be present.
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