How to test a power supply: 12 steps (with pictures)

The power supply is often forgotten when it comes to diagnosing computer problems. Checking the power supply is a must, because often it is he who is the cause of such problems as the appearance of a blue screen or severe malfunctions and sudden shutdowns of the computer, hard disk errors, as well as problems when starting the computer. Read on to find out what you need to do to test the health of your power supply.

Steps

Part 1 of 2: Checking the Power Supply

Step 1. Turn off your computer

When the computer shuts down, turn off the switch on the back of the computer's power supply. Disconnect it from the network.

Step 2. Open the computer cover

Disconnect the power supply from other parts of the computer. Disconnect each cable in turn.

Remember or take a picture of what was turned on and where, so that you can then turn all the cables back on

Step 3. Take a paper clip

Straighten it and bend it in a “U” shape.

The paper clip will replace the wires that are inserted into the power supply when you turn it on

Step 4. Press the 20/24 connector that normally connects to the motherboard

This is usually the largest connector on the power supply.

Step 5. Find the green contact and the black contact (pins 15 and 16)

You will touch the ends of the paper clip to the green and adjacent black contact pin. Remember to unplug the power supply first.

The green pin is usually numbered 15 on the diagram

Step 6. Insert a paperclip so that it makes contact with the corresponding pins

Let her go. Connect the power supply to the mains. Turn on the switch.

Step 7. Check if the fan is working

If the power supply is working and conducts current, then the fan inside the power supply case should spin when it is turned on. If the power supply does not turn on, check to see if the paper clip is intact and try again. If the power supply does not turn on, then it is not working.

This test does not mean that everything is in order with the power supply. It only allows you to determine that the power supply is capable of turning on and at least somehow working. Perform the following test to see if the power supply is working normally

Part 2 of 2: Verifying the Power Supply is Working Normal

Step 1. Check if the power supply is working properly and is supplying voltage to other parts of the computer

To do this, you need special software. SpeedFan is one of the best free software out there. Run it and check the temperature and voltage of the working parts of the computer.

If your computer does not work and does not turn on, proceed immediately to the next step

Step 2. Turn off your computer

Disconnect your computer from the network. Disconnect the power by flipping the switch on the back of the power supply. Open the computer cover and disconnect all cables that are connected to the power supply.

Step 3. Test the power supply with a power tester

You can buy such a device at a hardware store. Locate the 20/24 connector on the power supply. This is the largest cable connected to the power supply.

Connect the power supply to the 20/24 connector.
Connect the power supply to the mains. The power supply turns on and the light on the power tester comes on.

Some devices turn on by themselves, on some you need to find the appropriate button
Check the voltage value. The 20/24 connector can give different readings, but here are the main readings that we noticed most often:
- +3.3 VDC (Volt DC)
- +5 VDC
- +12 VDC
- -12 VDC
Make sure the voltage is normal: +3.3, +5, +12 may differ by +/- 5%. -12 voltage may differ by +/- 10%. If the indicators are completely different, then your power supply is not working well and needs to be replaced.
Check out other connectors. When you have verified that one connector is working, test the others, one by one. Unplug the power supply each time before testing.

Step 4. Check the power supply with a multimeter

Straighten the paperclip and fold it into a “U” shape. Find the green pin on the 20/24 connector. Attach a paperclip to this pin (pin number 15) and connect the other end to one of the adjacent black pins. Then the power supply will think that it is connected to the motherboard.

Plug in the power supply and turn it on.
Find a pinout diagram. There it will be written what voltage should be at which contacts.
Set your multimeter to VBDC option. Set the range to 10V if you can.
Connect the negative pole of the multimeter to earth ground (black pin).
Connect the positive pole to the pin you want to test. Check voltage.
Check the voltage to make sure it is adequate. If not, then the power supply is faulty.
Repeat the process checking all peripheral connectors.