How to check the PC power supply with a multimeter (guide)

A good power supply can make or break your computer, so it's worth knowing how to properly test your power supply (PSU) with a multimeter.

Testing with a multimeter

Checking your computer's power supply is critical when trying to diagnose computer problems and should be the first thing you should do if you're having problems with your system. Luckily, this is a fairly simple process that only requires a few basic tools. Here's how you can test your desktop power supply in just a few minutes to identify and fix any potential problems.

A good power supply can make or break your system, so it's worth knowing how to properly test your power supply (PSU) with a multimeter.

Checking with a multimeter

1. Check out the PC repair safety tips first.

Before checking the power supply, make sure you disconnect the AC power from the computer and properly ground it.

Security should always be a top priority when working on a PC. To ensure safety while performing this process, it is important to follow some safety tips. First, wear an antistatic wrist strap to protect your computer components from static electricity. Make sure there is no water or drinks around you. In addition, Keep all your tools away from where you are working on the computer, because if you touch any of these items and then touch any inside of the computer, you will short out (or even destroy) the motherboard or other parts of your system. (1)

2. Open your computer case

Disconnect all cables connected to the computer and remove its cover. You should see the power supply installed inside the case. Find out how to remove the cover by reading its manual or reading it carefully.

3. Disconnect the power connectors.

Disconnect all power connectors except for the main power connector of the power supply (20/24-pin connector). Make sure that there are no power sockets connected to any internal devices inside your computer (such as video cards, CD/DVD-ROMs, hard drives, etc.).

4. Group all power cables

Power cables are usually grouped in one part of the case. This is done to facilitate access and reduce clutter in the case itself. When testing a power supply, it's best to group all the cables together so you can see them clearly. To do this, you'll want to remove them from their current position and place them back in an area that you can easily access. You can use zippers or twist ties to keep them neat and tidy.

5. Short 2 pins 15 and 16 Out on the 24 pin motherboard.

If your power supply has a 20-pin connector, skip this step, but if your power supply has a 24-pin connector, you will need to short pins 15 and 16. You will need a paperclip or jumper wire to do this. wire. Keep reading and I'll show you how to short them out with a paperclip.

First, straighten the paperclip as much as possible. Then take one end of a paperclip and insert it into pin 15 on the 24-pin connector. Then take the other end of the paperclip and insert it into pin 16. Once that is done, attach the 24 pin connector to the motherboard. (2)

6. Make sure the power supply switch is

You will need to ensure that the power supply voltage selector is set for your local electrical system when you set up the power supply. If you live in a country where the standard outlet voltage is 110 volts, such as the US, then you should have a 110 volt setting. If you live in a country that uses 220 volts, as in most European countries, then the setting should be 220 volts.

Once you've made sure the voltage is set correctly, it's time to assemble your tools and supplies. To check the power supply, you will need an electrical tester or multimeter. You may also want to consider wearing safety glasses and gloves during this process.

7. Connect the power supply to a power outlet.

If your computer is not currently turned on, plug it into a working outlet before starting the testing process. This will provide enough power for the tests as they run. Please note that if your PC still won't turn on after checking the PSU, there may be other issues, but the PSU will still work properly and can be used in another PC or sold for parts.

8. Turn on the multimeter

Set the multimeter to read DC voltage. If you don't know how to do this, refer to the instructions that came with your multimeter. Some multimeters have a switch to select AC or DC voltage readings, while others have buttons that let you set the function and range.

Insert the black test lead into the COM jack on the multimeter. This is usually the connector labeled "COM" or "-" (negative) and is likely to be black.

Connect the red test lead to the V/Ω jack on your multimeter. This is usually the jack labeled "V/Ω" or "+" (positive) and is likely to be red.

9. Checking the 24-pin motherboard power connector for continuity

To check the 24-pin motherboard power connector, locate the 20-pin motherboard power connector on the power supply (PSU). This particular connector has two separate rows, each with 12 pins. The rows are offset and staggered so that all 24 pins correspond to one connector on the power supply. In particular, all 24 pins are set in an alternating order, where each row starts with a pin that shares a common connection with the opposite row's pin. Follow this pattern and then check for any visible damage to the row pins or motherboard 24 pin port. If there is damage to any of these two parts, we can recommend a certified repair from a local specialist.

10. Document the number that the multimeter shows.

After setting the multimeter to DC voltage, connect the red test lead to the green wire and the black test lead to one of the black wires. Since there are multiple black wires, it doesn't really matter which one you choose, but it's best not to touch both probes together on the same wire, as this could cause damage. Document what number is displayed on your multimeter display - this is your "input voltage".

11. Turn off the power supply and turn on the switch on the back of the power supply.

Then turn off the power switch on the back of the power supply connected to the AC outlet. Then disconnect all your internal devices from the power sockets. Reconnect all of these devices and document what number is showing on your multimeter's display - this is your "output voltage".

12. Turn on all your internal devices

After checking the power supply, turn off the switch again and reconnect all internal devices to the power source. (CD/DVD drives, hard drive, graphic card, etc.), replace all panels, as there is no reason to leave everything unplugged for long, so reconnect all your internal devices to power sources and you're done!

13. Connect the power supply

You can now plug the power supply into a wall outlet or power strip. It is very important that nothing else is connected to the power strip or surge protector along with the power supply. If there are other devices connected, they may cause problems with the test.

14. Repeat step 9 and step 10.

Turn on the multimeter again and set it to the DC voltage range (20 V). Repeat this process for all black wire (ground) and colored wire (voltage) connectors. This time, however, make sure the bare ends of the multimeter's probes don't touch anything when they're inside the power supply connectors. This can cause a short circuit or electric shock if there is a problem with what you are testing.

15. After testing is complete, turn off the computer and unplug it from the network.

After testing is complete, turn off and unplug your computer from the network. It is important to disconnect all components from your computer before you begin troubleshooting or repairing.

Tips

• The most important thing to remember is that the voltage, current, and resistance readings you get will vary depending on the brand of multimeter you use. Therefore, always read your multimeter manual before attempting this test.
• Check all connections and make sure the power supply is connected to the motherboard and all other components.
• Make sure the power source is turned on and that there are no blown fuses or circuit breakers that have tripped.
• Do not plug anything into the wall outlet while checking the PC's power supply with a multimeter, as this may damage both devices and/or cause injury.
• If you are in any doubt as to whether your PC's power supply is working properly, check with your computer manufacturer for more information before proceeding with this guide.

Take a look at some of our articles below.

• How to test an electric fence with a multimeter
• How to find a short circuit with a multimeter
• How to test a circuit breaker with a multimeter

Recommendations

(1) PC - https://www.britannica.com/technology/personal-computer

(2) Motherboard - https://www.hp.com/us-en/shop/tech-takes/what-does-a-motherboard-do

Video links

Manually Test a (PSU) Power Supply With a Multimeter by Britec

How to Easily Test a Computers Power Supply with Simple Tools

How to Test the PC's PSU