How To Test A Power Supply Unit (PSU) With A Digital Multimeter | Advanced Troubleshooting 

I have assembled so many desktop computers and troubleshooted laptops, today, I have learned a new lesson from you. Your demo is outstanding. Everything is very clear. I felt as it is done in front of me. Awesome Sir, Thank you...

1. connect pin 15-16 to turn PSU 2. connect black needle to pin 24 and red needle to pin 13,14, 21,22,23 3. connect black needle to pin 14 and red needle to pin 1,2,4,6,9,10,11,12

This is a good intro for entry level troubleshooting for a PSU, but what I would call "Advanced Troubleshooting" would be testing the voltage lines under load, which is a little more difficult. As a PSU could appear to be working just fine until you get it under an extensive load like in a video game or rendering session whereby the PC would restart due to a drop in voltage (most likely on the 12V supply) from a lack of current, measured in amperes, and is otherwise not sufficient under such load.

Great video dude! As the start I didn't even notice the other person in the video. When the hands moved I was like hey! Hold on a minute 😅

Thank you so much for this video. It's been over 20 years since I worked as a Technician. You reminded how to be one again. Pointing out the the Power On jumper did it for me. Appreciate the safety tips as well.

Thanks! Excellent video. I used this method to make sure a psu wasn't faulty, it wasn't. Turns out disconnecting absolutely everything from the motherboard and jumping the clear CMOS pins brought the PC back.

Our PSU was great, the problem was with the Power cable. Thank you for a very informative diagnostic video.

dude for like 89% of the video i thought the black hand sweater thing was like an automatic weird unique prop holder. it was moving erratic an creeped me out. but when you told it to hold this and it lurched forward i realized it was a humanoid.

Hey King, you dropped your crown! Thanks for the detailed instructions on how to check PSU!

This was a very helpful video. Helped me and my son to trouble shoot effectively a non working PC that he has assembled. The problem was that the 24 pin connector had no white wire. We could find that out easily. Thank you for this great and useful video.

Nice job with teaching.... One thought for doing this alone (We all don't have a lovely assistant with us)..... Use an alligator clip on negative (black wire) side of multimeter and clip it to metal on PSU case grounding it - confirm a perfect ground by checking resistance/ Ohms test between clipped lead and any of the ground wire - (actually if you are having issues you can check all of the ground wires with this test).. Thank you, much appreciated.

Good video,my problem is faulty pc start/up then pc runs ok.i have been suspecting power supply to be the problem so with the help you have shown i will now test my power supply unit following your advice and chart.thank you.

Very easy to understand. When I test a PSU, I also test all other cables.

Excellent video I learnd how to turn on PS without motherboard. Also very good picture of power plug pinouts and you even added the tolerance ranges for each pin Excellent. May I borrow your assistant hands i need some one to hold things when I am working. also nice touch zooming in on the power cord symbols. I also like that you were talking us through the tests so I new exactly where i was. Subbed and Like cheers

Great video and thank you so much for it. Lucky me found it too. Ill just echo what everyone else said. Even in a quality tech school you dont get it this easy and precise almosat like one on one instruction. . The pinout charts were beautiful. Now the PSupply im only 20% worried about i can test instead of testing it first blind with the new pricey board and processor i just installed. Thanks guys. Edit to add: Just finsished the test exactly as shown and voila i KNOW i have a 100% power supply on all circuits...nice!!!

Good tutorial, helped me through the process without doing injury to myself or my computer and happy to report my PSU is 100%. Thanks!

Thank you! I know the power supply works now, even got the drives working. Now need to troubleshoot the motherboard and the power switch.

Thanks for the video. Everything was to spec for my Thermaltake TR2 600W... EXCEPT the blue wire read 11.17V I dont know if this is anything to worry about or not, but I can confirm my PC black screens and self-reboots when playing most games and also I have had trouble just getting it turned on. The fans and LEDs would come on for a second but then shut right off. It all seems like a power issue, but also a temperature issue too as the CPU and GPU run a little warmer than what idle specs say. CPU does shoot up to 85 Celsius time to time (even with new thermal paste), but the graphics card usually reads 49-55C° even while gaming. Been messing with this PC on and off for months lol

Thanks for the video, this helped out a lot when I was troubleshooting a new PC build.

Who is the robber???😂😂😂

One of my readings was -12.82 volts on a 12 V pin which is outside the 4%. Is that a problem ? Excellent, clear video. Thank you very much.

Very well done! I tested the same PSU; so this video was perfect. Thank you.

It should be noted that you can sometimes have failed power supplies that output at a voltage that's within tolerance with no load on the voltage rails. While it's more common that a rail will just outright fail, I have had instances where a PSU will output the correct voltage when measured, but when loaded it drops down to next to nothing. What I do the mitigate this is to put a modest load, say, a 20w incandescent lamp or a resistor on the rail I am testing and then measure voltage. This will yield a more reliable measurement when testing for a failed supply as it should also factor in how much voltage drop you get on the rail when it's under load. Additionally, a time-saving trick: every wire in the PSU is grouped by voltage on the output section of the supply's circuit board. This means, that unless you have a multiple +12v rail design (which can be seen in higher end power supplies), that a +12v on your EPS+12 connector and a +12v on your SATA power / MOLEX / FDD connector will be connected to the same point on the power supply, therefore should have continuity between the two wires. For this reason, I tend to simply test one wire from each voltage rail. Unless it's a multi 12v rail supply and I don't know where the wires are allocated, then I will test all of the wires with a load across my probes to confirm that all rails are working properly.

Good videos, straight to the point and very informative. Thanks !

My multimeter exploded durring the cable check. 😂😂 suggestion: tell them to not use a cheap ass multimeter 🤣

what reason do you join green with ground...?

Mine came color coded all black. So without your chart there is no way to tell. Thank you for providing this detailed information. Reason for me to do this is my computer will turn off by itself at random. Other times whea uncorrectable error bsod. (That you’ll set cpu vcore to 1.270v ) Now motherboard won’t boot. If you’re facing this it’s the psu not your ram, mb or cpu. Hopefully save you some time if you’re facing this issue.

I need a pair of those helping hands. I always run out of hands. Thanks!

You have been very helpful, knowledgeable, honest and practical. Stay blessed

Oh cool, I think my motherboard is dead. Thank you for the video, this has saved me from diagnostic fees. I love working on my own things.

for people from canada watching this our standar voltage is 110-127 V

Very well explained. Thank you. Learned something today 👌🏽

Straight and clear explanation, thanks for the basic information. Sometimes I use my GF as a table top or a hanger too... (jk) Why don't you wear gloves btw, if the other person does? Next time choose anti-static gloves ;-)

hi, thanks for the video. i learned a lot. question please... how do i check if the PURPLE 5v on my power supply has continuous power? thanks in advance.

it is very good tutorial for beginner electronics expert.

Thank you, brother! Everything worked exactly as you said it would. Very Helpful.

assistant gimp lectrican - never knew that was a thing - better than a grip stand

Thanks brother! This was a simple lesson and it helped a lot

Thanks a lot for this great tutorial : very good step-by-step explanations.

I was having an issue with a Corsair power supply I just bought and returned - tested fine on a multimeter, but still was shutting down in actual use. Double checked everything, old EVGA power supply works fine. Bizarre

Exactly the kind of video I was looking for. Gracias!

Thanks for the video! Keep up the great work!

This is a very helpful videos. I just subb for life!!! I tried this steps and follow everything on multimeter. But I always lack 2 volt to all of the pins. Does it means that my power supply is bad and needed to be change?

Been having these annoying random restarts for months now. 6 months old pc, built with all new parts. It's been driving me crazy. Never thought of something so simple as measuring the voltage coming in the PSU. Voltage drops down to 215V AC regularly...way below that 6%...

I like the consistent uploads, great work

Thank you for your service sir 🖖

Thanks for this, although I don't know how to feel now, because apparently my PSU is fine, so it could be my graphics card or motherboard, which is a lot worse of a problem and potentially a lot more expensive. Oh well!

Great video! Helped me fix my computer!

the black gloved robber is an experienced jump start car theft

Where you plug in the power cord which is female prong and the power supply unit's are male prong ( assume the unit is an SMPS power supply nonlinear), if you measure for continuity on that male prong end on the power supply should there be any continuity there and if so roughly what ohms or should there be no continuity? ( I assume it must show some sort of continuity or there is some sort of open in the circuit somewhere. Or if very low continuity I assume there is a serious short somewhere. Does that sound about right?)

You're a champion, thanks so much for the video, was super helpful

What is tolerance for purple wire in V on 24pin connector on PSU? I have reading of 4,6V? All others are fine.

This video was very helpful, thank you!

My computer turns on but nothing appears on screen. I understand this is likely a video issue of some kind. My question is if it is possible to be a power supply issue. Almost all of my values are between .05 and .20 volts outside of the acceptable 4% tolerance range. It is a 6 year old system I attempt to repair sometimes. Can voltages outside of the range to this extent cause an issue like mine? Thanks

Masha allah bohot acha video very good method to teach us about pwr supply thnx and shukran bhai

I get PC shutor freeze, Kernel 41, ID 63, tried everything and after watching this video I find out that my blue 12V rail is giving me -11.44V, so the PSU is faulty.

if the voltages are correct but what if the power supply isnt providing the needed current, testing the voltages i think is only proving one part of the power supply is working

great video: but...wouldn't it be best to do those tests "under load", ie: while the computer is working? by probing a HDD connector plug for 5v and 12v, other voltages? find then on the motherboard or in extra PSU plugs..

Glad to see that I am not the last man on Earth that can use a meter. Good vid! Thank you

MY PSU IS FUCKED SO GREAT VIDEO THANKS

Thank you so much while i know these things but your video is excellent and so detailed

If your PSU is causing an intermittent loss of power to your system, will this test reveal a failing line for sure or is it a situation where it may or may not show up on this test?

thats what i want to this video,best tutorial, thats why i am subscribe to your channel thanks for sharing

Thank you so much for this! Very helpful

When you test the motherboard plug supplier, is it necessary to test all the wires of the same colour in one connector, eg all the red +5V wires. Surely if one red gives a correct reading then all the other reds will give the same as they are supplied by the same rail in the PSU. Likewise for yellow, +12V and orange, +3.3V. Wouldn't testing one yellow and one orange wire be sufficient? Also why is it necessary to test the mains voltage? It's what voltages come out of the connector plug that's important?

So if my computer isn't starting up (not even going to POST, the power light is just blinking) and all the pins are reading properly, does that mean I can assume the problem is with the motherboard?

I love the Mastec multi meter

Hello sir what do I need to do if I requare 13-18v by 350mili amps ? Is it posibel to use same or dimilar polarity leads to get centrain out put voltage? I atempt to use an satelite dish motor manuali activate that thing because I don't have an reciver .

When I test this I am only getting 3.3v from the green pin to ground shouldn’t it be 12v? Also I’m not getting any voltage on any other pin except pin 9 I’m getting 5v. Does this mean my psu is bad?

hi bro. my pc suddenly restarts now. what to do? power supply has current. but restrts how do i make sure it is power supplyonly?

Great help/ instructions!

Thank you for your tutorial !! I found a Xilence Full Modular Bronze 80% 750W PSU in garbage and I didn't know how to test it. It's working perfectly !! Why would someone would throw away such a good PSU ? Stupid people !

Great video! Thanks for making this.

Needed this, just about to check my dads. Built the PC ages ago and always fine. I hardly ever have to do this so always have to look up how to do it again as always forget.

Hi , Paper clip test with the black one my psu fan not spinning. But I try the green with red the fan working. What is that mean? Thanksss

Very helpful- Thank you!

gloved hands are weird...but informative video. thanks

Cool ! I was able to test that my power supply is outputting a proper 12v because of this video, thanks :) ...But please, treat your assistant as a human being next time, it felt a bit awkward !

My computer is restarting when i turn on game. I measured all V but blue wire is giving 11.25 which is out of ur recommended volt. So does it mean i need to get new power supply?

Very informative. Thanks.

Is that possible that current range may lower down if the powersupply seems to be faulty. If that so that how can we check it when my multimeter can check upto 20 Amps of current

Your video is very helpful.

You're a legend thanks bro

I got a fully modular psu without any cable how to test it?

Excellent. Thanks. My PSU is good.

Masha Allah Thank you and I need your support. I was wondering if you can explain the power supply or charger output. Means like I have 9V 100mA output why when I connect with series 10 ohm I am not getting like 900mA rather I get 315mA and if I short it it will not go over 430mA. 1 ohm will give 430mA, 6 ohm will give 360mA instead of 1500mA, 330 ohm will give 35 mA instead of 27mA, 1k ohm will give 12.9mA instead of 9mA. My voltmeter is connected in series and setting on amp. So I am getting less than what it should be.

Thanks 👍 helped me trouble shoot

Good vid but my blue and yellow wires wont read on the 20v setting so i put it on the 200 setting and they read 2.16 and my red and purple are at 8.5v and orange is 5.5v is my power supply stuffed any advice would be appreciated

Ok all pins slightly above the spec except Pin 14 - the blue one. - Which is showing -11.46v which is out of range. The Computer is old but working prior to going shopping - came back won't even post despite replacement of iffy capacitors and a graphics card swap. What does this Pin 14 supply and could it have just slipped below the threshold to stop something working. FYI the original graphics card was showing an LED Warning light hence the GPU replacement but this hasn't worked. One side of me says the low PIN 14 output is the issue but then you see that PCI Express slots dont have a a-12V feed. Will buy a new PSU but don't want more expense if this is not the issue.

My psu fan spins and then stops after 10 seconds. Is this normal?

Excellent that was what I was looking for, like knowing whether the power source worked or not. Thanks

When I do the following;- 1. connect pin 15-16 to turn PSU (all Ok) 2. connect black needle to pin 24 and red needle to pin 13,14, 21,22,23 (Ok- all is good) 3. connect black needle to pin 14 and red needle to pin 1,2,4,6,9,10,11,12 (WTF ??) The First set are spot on; but the 2nd set Are either 3x the listed Voltages (1 & 2 supposed to be 3v but are 15.57..v), and (4, 6 & 9 supposed to be 5v = but are 17.4v) & in the case of 10 & 11 they are near zero volts at 1v? or something;- ( '1 . ) . And next, the 12th pin (supposed to be 3.3v) is 15.6v or so Looking inside the PSU is relatively clean and looks perfect. PC was running fine... but PUBG kept crashing halfway through the game. Then when I re-booted after the BIOS it went dead with one white underscore on a black screen. So, assumed CPU or GPU, but then wondered 850W Platinum PSU made in China maybe at fault. Wondering if i7-4770 CPU could have caused it?; or even TUF Motherboard? Or Strix GTX1070?

Yellow showing +11.64v and blue is -11.34v. Is it fine.? Mother bord failed 3 times, service person told to check smps.

So my PC broke and I have to replace the motherboard, processor and RAM (The motherboard is failing and I'm upgrading to a better processor and for that I need a new MOBO). Anyways, I decided to test my PSU in case it was failing so that I could make sure that it wasn't going to break any new components I bought. Turns out some lectures gave between 23.8v to 15v. I'm not an expert, and I tried to make sure I was connecting in the right ports many times, and I'm pretty sure I connected it correctly, but no PSU should givbe more than maybe 12v? In fact the chart on the side of the PSU says it gives a maximum of 12.5v. Guess I'm replacing the PSU as well.

This was very useful

Thanks for the video 🙂!

Interesting! Mine is missing voltage. The #20 slot on my 24pin is completely empty. Is that abnormal?

Good Day how to adapt an atx source for pc dll mini. larger atx connector and the smaller dell all of 24pins

Is It a bada sign if the fan Is not starting once Power on? I mean if the fan Is not even starting could bei worth to continue with the Test?

hi my blue cord comes up as -11.1 so does this mean the power supply is no good and need a new one? or can i fix this? thanks