How to test computer power supply using Digital Multi-Meter?

[Almighty1]

I was wondering what is the correct way to test a computer PSU on all voltages including -5VDC with a digital multi-meter just to make sure it works before connecting it to the computer. This is a PSU that does not have a power switch on the PSU itself.

[Ed Hall]

Re: How to test computer power supply using Digital Multi-Meter?

You might review this link and see if it helps:

How To Manually Test a Power Supply With a Multimeter

[kaboom]

Re: How to test computer power supply using Digital Multi-Meter?

You might review this link and see if it helps:

How To Manually Test a Power Supply With a Multimeter

Wow! So I bought all my load resistors for nothing!


It's not a proper test without a proper load!

[Ed Hall]

Re: How to test computer power supply using Digital Multi-Meter?

Wow! So I bought all my load resistors for nothing!


It's not a proper test without a proper load!

I guess I missed the word "correct" in the OP's message. Of course, the correct way is to use "proper" load resistors and professional equipment.

[Almighty1]

Re: How to test computer power supply using Digital Multi-Meter?

Thanks for the link Ed Hall as what I wanted to do was make sure the PSU was working after the recap so that I can test it without creating some short or something else that might fry the entire motherboard and everything connected to it so all that was needed was to get it powered up and see what voltages come out of the pins and if it's anywhere close. For the actual load, I can just connect a HDD or something but the PSU tested fine and it works back in the system...

[Agent24]

Re: How to test computer power supply using Digital Multi-Meter?

Yes, you can check all voltage rails with voltmeter for a quick go\no go test, but like already stated, it's not a proper load test, and you aren't measuring ripple and noise so you're missing more than half the picture.... unfortunately that requires a proper load tester, oscilloscope etc.

[Almighty1]

Re: How to test computer power supply using Digital Multi-Meter?

I never ask for that thorough of a test. All I wanted to know was if it's outputting the correct voltage or a short since I'm just trying to prevent the PSU burning everything connected to it. The actual load can be tested after verifying the PSU actually runs and outputs a voltage similar to what it's supposed to since this is a PC Power & Cooling Turbo-Cool 450ATX and there is a daughterboard that I ripped off the trace on that I repaired in addition to a copper board that sits on the top of the main PCB that has the mask areas of two different capacitors going through it and last connection is actually a guess as the soldered wire fell off so I don't know where it goes other than that is exactly where it sits on top so wanted to just see if it powers up and if each rail outputs the correct voltage and not like 12v on the 5v or 5v on the 12v. Other than that, the rest can easily be tested by running the system and testing for stability. I don't have the equipment to measure the ripple or noise so that's not of a concern since I'm fixing only once every 14 years, not like it's a regular thing. I just want to verify it can turn on and check the voltages without a load to be sure it's correct and it doesn't have black smoke coming out, all is fine. I never asked about testing it under load either as that can be done using another method by actually running the system 24x7x365 like usual which is more reliable. The PSU went out of service on September 10, 2014 and I need to return the borrowed PSU back to Best Buy under the 45 day return policy so just need to see if it works in whatever way possible before actually putting it back in service. If I had all that other equipment, I would be manufacturing PSU's...

[senz_90]

Re: How to test computer power supply using Digital Multi-Meter?

I never ask for that thorough of a test. All I wanted to know was if it's outputting the correct voltage or a short since I'm just trying to prevent the PSU burning everything connected to it. The actual load can be tested after verifying the PSU actually runs and outputs a voltage similar to what it's supposed to since this is a PC Power & Cooling Turbo-Cool 450ATX and there is a daughterboard that I ripped off the trace on that I repaired in addition to a copper board that sits on the top of the main PCB that has the mask areas of two different capacitors going through it and last connection is actually a guess as the soldered wire fell off so I don't know where it goes other than that is exactly where it sits on top so wanted to just see if it powers up and if each rail outputs the correct voltage and not like 12v on the 5v or 5v on the 12v. Other than that, the rest can easily be tested by running the system and testing for stability. I don't have the equipment to measure the ripple or noise so that's not of a concern since I'm fixing only once every 14 years, not like it's a regular thing. I just want to verify it can turn on and check the voltages without a load to be sure it's correct and it doesn't have black smoke coming out, all is fine. I never asked about testing it under load either as that can be done using another method by actually running the system 24x7x365 like usual which is more reliable. The PSU went out of service on September 10, 2014 and I need to return the borrowed PSU back to Best Buy under the 45 day return policy so just need to see if it works in whatever way possible before actually putting it back in service. If I had all that other equipment, I would be manufacturing PSU's...

I think you are the one asking "how to test computer power supply correctly?"

Agent24 didn't ask you to buy oscilloscope or manufacturing PSUs. he suggest you "the proper way" and the answer is with a proper load such as big wattage resistor and see what happened through oscilloscope. I can asnwer this easy question. YES you can "test" with HDD or fan as a load.