How to Use a Multimeter to Test a Power Source

How to test a power supply with one of the best multimeters, but you can use the one you already have if you follow these steps (14 steps).

Info Article Alert: One of the problems that are currently least seen in the world of custom PCs is that of home repairs and tests since as a rule, the quality level of the components is very high. Read our article on “How to test and test a power supply with a multimeter” to diagnose your power supply at home. 

If you think something is wrong with your power supply, you should test it. A multimeter is one of the easiest tools to use for this. This is the manual way to test a power supply. If you want the best power supplies, you can buy a power supply tester that can automatically find problems.

If this test is done right, it will show if the power supply needs to be replaced or if the unit is working as it should. You should know that not everyone should take this test.

It is only recommended if you have done electrical tests before and know what you are doing. If you aren’t careful, it can be very dangerous. Sometimes it’s better to just replace it with one of the best pc power supplies.

Assuming you already have a multimeter, here are the steps you need to take to do this test. You should plan to spend between 30 and 45 minutes on the test. If you want to be more thorough, you could spend more time, but now you know how to check a power source.

Info Article Alert: One of the fundamental parts of a computer is its power supply or power source since all the necessary energy is distributed from there through cables for the motherboard, if you don’t know what PSU you’ve in your PC, read our article on “How to know what power supply my PC has? to find the answer.

Make sure you know how to test a power supply in a safe way.

In order to use a multimeter to test the power supply when fixing a computer, you have to know how to do it safely. 

Info Article Alert: The power supply unit is an important part of a server. Without it, your IT infrastructure would not be able to work. So, it shouldn’t be a surprise that most systems come with a power supply. Read our article on “What does the term “Power Supply Unit” (PSU) mean?” to find out more about PSUs and their usage scenarios.

How to check out a power source

1. Make sure you know how to test a power supply in a safe way.

In order to use a multimeter to test the power supply when fixing a computer, you have to know how to do it safely. This is because the process can be dangerous. Some of the most important things you need to think about are:

1. Turn off everything

Most people might think this is obvious, but it’s important to remember that you should always turn off a computer’s power switch before trying to fix it. Unplug your computer while you’re at it to give yourself even more peace of mind.

You’ll have to wait a few minutes after you pull the plug to start fixing your PC. Capacitors are small pieces of electronic equipment that can still hold an electric charge. Even if the storage time is short, it’s better to be safe than sorry, and this is the most important step for testing a power source.

2. Strange smells and smoke

When you smell something burning, you always need to act right away. Along with seeing smoke coming out of the box or anywhere else,

these are signs you should pay close attention to. When a computer part breaks, you have to let the whole thing cool down, then find the problem and fix it quickly. Most of the time, this is done by making a new part for that part.

3. Never wear hand jewellery

Always take off any metal rings, bracelets, or other hand jewellery before working with high-voltage devices. This is especially important when testing the power supply, since anything that conducts electricity can kill you.

4. Know when to stop and check the source of power.

If you are fixing something and you find a label that says the part can’t be fixed, it is very important to leave it that way. Don’t try to ignore this statement, because there are many PC parts that can’t be fixed, sometimes not even by experts. This warning will show up on parts that are dangerous or very sensitive.

Put the case open

2. Put the case open

Turn off the computer and unplug all the cables. Move the PC tower to a better place to work and start opening the case. For this, you will probably need a screwdriver.

3. Disconnect the power cords.

Make sure that the power connectors for each part inside the case are no longer plugged in. You can find out if a certain cable is a power connector by following it to the computer’s power source. You don’t have to take out the power supply or disconnect the data cables.

4. Keep your power cords in order.

It is recommended that the power cables be moved away from the case and to a different spot. When it’s time to test the connectors, it will be easier on you if you keep them in order.

5. Find pins 15 and 16 on the power connector on the motherboard.

You’ll need to figure out where these pins are because you’ll need to cut them shorter later. We are using a standard ATX motherboard for this test. If you can’t find them, look at a pinout table like this one.

6. Make sure the switch on the power supply is set correctly.

If you live in the US, you should set the switch to 110V/115V. If you live somewhere else, you’ll need to find out how to do this for your country. should be able to help you with that.

7. Connect the power source

Now you need to plug the power supply into an electrical outlet. Make sure the power switch is on (if there is one on the back). If you shorted the pins the right way, you should hear the fan start to run. This is a good sign, but it’s not enough to say it’s working perfectly.

8. Switch on the metre

Turn on your multimeter and move the dial to Volts DC. If your device doesn’t have auto range, you should set the range to 10.00V.

9. Check the power plug with 24 pins

In this step, you need to connect the black and red probes to a ground pin and the power line you want to test, respectively.

Again, use the table at this link as a guide to find where the 24-pin main power connector and its lines are on the motherboard. properly if the voltage on the lines is right. It’s also important to make sure that each pin has the right finish.

10. Write down the values of the multimeter.

You’ll need to write down the number for each voltage you tested and then make sure it’s not below or above the specific voltage tolerance. The right ranges for each voltage are shown in the third table in this link.

If you find that some voltages are higher than what the power supply can handle, you need to replace it. If there are no problems and the voltages stay in the right range, the power supply is working. You could stop testing here,

but it’s better to keep going and see how the power supply works when it’s being used. This could be important if you want to make sure your power supply works well. Here’s what to do if you decide to do that. On the other hand,

11. Turn off the power supply and take it out of the wall.

12. Plug in all devices inside the house that need power.

Here, it’s important to make sure that everything (hard drives, video cards, other drives, etc.) is connected correctly. When you put the motherboard power connector back in, be careful not to make a short. Connect the power supply and turn the computer on as usual.

13. Test and record as you did in the previous steps.

We will test the voltage in the same way, but this time we will look at other power connectors, such as SATA and peripheral connectors. You have to look through the pinout tables again to find the right pinouts.

14. Take this quiz

If the power supply passes all of the tests, you know it works, so you can turn off the computer and put the case’s cover back on. You might also need to do a replacement.

In that case, you won’t be able to turn the computer back on until it finds a new power source. You can also go back to fixing the problem with your computer that you were working on right now.

James Hope
My name's James and throughout the long term. I have actually assembled numerous PCs for me as well as my companions. I love gaming, programming, illustrations planning and essentially whatever has to do with PCs and innovation.