Computer power supply PSU fault troubleshooting and repair

[@kesavachandran828]

I became Computer savvy at age 70 gravitating to Linux, able to adapt hard modems to Red Hat 8 with help from Connexant Canada whose beta driver helped get to go dial up .When my old AMD socket 7 PC packed up I took it apart fixed it to start my entry into hardware,got some good tries reviving dead hard disks.At 83 now SMPS posed problems had 2 units unserviceable.Till watching your excellent video a couple of Hrs ago the fears of tinkering with high voltage ,(we use 230 V Ac) was a damper.I took both my "kaput" power units and one by one checked for faulty capacitors,resoldered suspected dry joints,then rectifier diodes using my multimeter.Your tip about shorting green and black wires to start the fan going was an excellent tip,even Scot Mueller's bulky tome is not that explicit.I didn't get any nasty shocks and am a winner not having to buy replacements or depend on a service guy.

[@alwaysafix]

Awesome news, and congratulations on your fix. Thanks for watching!

[@johnvrock6668]

I converted an old ATX PS into a bench power supply. It quit working so I checked the caps and two were puffed and had leaked. Found two matching caps in my box of salvaged parts and put them in and it is now working fine. Would never have thought of replacing caps before seeing this video. Only took about half an hour. Thanks.

[@alwaysafix]

Congratulations on your fix and thanks for watching.

[@cougalways]

Thanks for taking the time to record and share this. I have a small PSU unit I can't find a replacement for so this is great. Thanks

[@anthonyrhodesevents7097]

I see a lot of these videos and then people commenting about it not fixing there issue, There is a lot more to these repairs then capacitors , Transistors are another massive fault or in larger psu's IGBTs, Always remember to discharge the unit before work though the main filter caps pack one hell of a punch!

[@tuneup1200]

The problem with your power supply is VERY common. The problem with it was my first guess . Every power supply that Ive pulled apart had failed 1000uf capacitors. Its because they are rated at 10 volt but they are on the 12 volt supply circuit. This decreases the life of the power supply to 4-5 years, sometimes shorter depending on how many 12 volt devices are plugged into it. On my computers, the first thing I do on new power supplies is replace these with 16 or 25 volt 1000uf capacitors before installing it.

[@krisachar]

Will try this next time.

[@alwaysafix]

Thanks for reminding me, I've updated the description with that vital information. Thanks.

[@metricmine]

A capacitance meter isn't always best to determine bad capacitors. A lot of times a capacitor may look good and measure good, but still fail in circuit. You need to measure their ESR with an ESR meter. Very good investment, especially for switching power supplies, which almost all electronics use these days. Know for sure which capacitors are bad without guessing. You can test capacitors in circuit without the need to desolder, so you can easily test all on the whole board. Also if a power supply does not turn on, the first thing to do is test for the 5V standby voltage. This will give an indication of where to look for the fault.

[@bausedap69]

Good Video Tutorial. Just remember to discharge the caps before working on it.

[@alwaysafix]

Jerin Jassua If your fuse keeps blowing, I wouldn't bother trying to fix it. I would recycle it and buy a new one. Thanks for watching.

[@alwaysafix]

If the caps are swollen, this is a sure sign that its faulty. Since the capacitors are not expensive, just replace all the ones around the faulty capacitor. If it works, at least you'll end up with a spare power supply.

[@workinalday4351]

What about the fuses on these. On some of my power supplies the capacitors may be bad, there are a couple of different types of fuses, along with a resistor that seems to go. One type glass tube fuse. 2nd type is a little square white pc board fuse. I would think these would be bad on your power supply along with the Caps! Very easy to test and replace, just wasn't sure why you didn't check any on your power supply?

[@yuppiehi]

Wow, you could have at least checked the voltages on the ATX connector before even placing it into the PC. Although the fan is spinning, there may not be enough power coming out of the PSU.

[@alwaysafix]

This PSU has been fitted to the computer since that day of the repair, and Im happy to report no issues. Thanks for watching.

[@TobgayBBS]

your viteo helped me very much, i repaired one but its gating my pc fan on and off, so pls help me what i can do next?

[@alwaysafix]

Like I mentioned in the video, I recommend replacing bad caps and any other damages to transformers, diodes etc. it's not worth the effort and better to just replace the PSU.

[@pdgiddie]

As seen in the video, many capacitors can read a correct capacitance value, but if they have a high ESR (Equivalent Series Resistance), they are no good. If they're bulging, the electrolyte has dried up, and the ESR will be high. This means that even if the capacitance meter suggests they're OK, they actually won't be able to perform their filtering role correctly.

[@alwaysafix]

It was just for the sake of the video to show measuring bulging caps with the capacitance meter are almost always defective. Always replace bulging or leaking caps.

[@TheJavaSync]

If there isn't 5v standby & all Transistors are OK - any sugestion to fixed it, Sir?

[@alwaysafix]

It sounds like it might be time to replace the power supply board

[@JahanZeb1976]

Excellent video mate! Keep up great work. Regards,

[@alwaysafix]

Much appreciated mate! Thanks for watching.

[@alwaysafix]

Most people attempting this repair themselves will not have much more than a multimeter. In this video I use my meter to prove bulging or leaking capacitors to be bad.

[@mandycopraya8663]

hi mate, i only made an acc. for this matter, my psu is not dead but is dying, 12v rail is giving me 11.8v and when i connect the 3rd hhd gives me the classic i wont start psu failure black screen,its a 1000w coolermaster psu, im familiar with electronic comps. and i would like to know if there's a common reason for that like caps failure or something that i can fix before it fully dies, thanks in advance.

[@OneGun09]

At 2:50 when you do the capacitance test, how do you determine whether the cap has gone bad? The reading was ~.81, how do you know what it should have been? Thanks.

[@cheappartshellas6229]

Very good video! But don't enough to works the PSU but we must measurements the voltages if are correct. The -12v is very important voltage and if don't exist there is serious problem. Friendly Regards! CheapParts Hellas

[@kittenvideosareawwww]

thank you so much! I'm going to go repair my power supply now!

[@alwaysafix]

Thanks for watching.

[@MukeshKumar-us7rs]

Good video for help to troubleshoot a pc

[@alwaysafix]

Much appreciated and thanks for watching.

[@solraczilec4960]

All of my damage PSU's get low voltage output like 4.7v in 5v rail or somtimes 11.4v in 12v rail.. but when i open it i don't see any bulging capacitor.. can you spot the problem?

[@rumjar1986]

hey I was just wondering if you could help me troubleshoot this darn powersupply. now this one is just weird and all back the front with the fault. I can get it to power on and run while plugged into the motherboard but when I do the short between the green wire and the earth wire/black. I too had a few bunch of dead caps and replaced them. I am at a loss and please any thoughts would be greatly appreciated.

[@alwaysafix]

Josh Rumballe If you did not replace all the caps, I suggest thats the first place to start. Even if the caps are not swollen, they can still be bad. Good luck!

[@criticall9113]

alwaysafix Hi , i wanted to ask a question about my powersupply ! When i turn it on , my Dell PC show up the orange light that means something is not working right , but sometimes after trying many times my Pc will start normally , how can i fix this problem , this powersupply seems to work but not everytime ! Pls help

[@alwaysafix]

The capacitance meter measures the mf which is printed on the side of the capacitor. If reading is within 10% either way I consider it ok.

[@alwaysafix]

Glad to be of help!

[@marnee8277]

Hi, my psu wont turn on. I check the insides, all caps look good and also the fuse doesnt look burnt. should I replace the fuse first? The ends of the fuse are soldered thats why I am asking here first. thanks

[@alwaysafix]

Mar nee You can check the fuse for continuity with a multimeter. Good luck!

[@nathanaelmittag5099]

How much do you charge to rebuild power supplys. I have one for DVD duplicator the fuse was blown I changed it immediately blew again if you do reveal them how much you charge I cannot afford $350 for a used one there very expensive I can afford may be $40 to about $80 for one or not your typical power supply that you not have a power port for motherboard I just can't use a tester on it if you do please let me know

[@alwaysafix]

If you saw sparks within your PSU, I recommend replacing it.

[@alwaysafix]

@tunup1200 Thanks for watching.

[@ernststavroblofeld1961]

+alwaysafix Excellent video!

[@alwaysafix]

+Ernst Stavro Blofeld Much appreciated and thanks for watching.

[@ernststavroblofeld1961]

+alwaysafix Well deserved. Right up to the point. Very good. Question: What in your experience is the 3rd most likely part to fail after the fuse and the capacitors? (no smell of burning (smell was also a good reminder)) ;->

[@alwaysafix]

+Ernst Stavro Blofeld Have you tried a different PSU on the motherboard to make sure it is the PSU in the first place?

[@ernststavroblofeld1961]

alwaysafix No. But the loud bang came clearly from the PSU. I already repaired it. One of the two stw20nm50 power mosfets shorted.

[@alwaysafix]

Testing the damaged capacitors was for demonstration purposes only.

[@thesummertune]

Hi, if the capacitors measure 20-30% more of the printed value, they are still ok or it's better to replace them?

[@alwaysafix]

+thesummertune Yes, those capacitors are still ok.

[@thesummertune]

OK, i've replaced some capacitors from a power supply for pc, two big 330uF but their value was about 200, and a 470uF because it was about 700uF, unfortunatetly the PS still dead. No visible damage on other stuff.

[@krisachar]

Nice information. Thanks.

[@alwaysafix]

👍

[@hooperwille]

can you test active PFC PSU with this method (bridging green black wires)?

[@alwaysafix]

Yes you can, but don't leave it running long as it's not good for the power supply. Thanks for watching.

[@S1INDHTEC]

pls tell me without capssiter how can other fault find or check component with multimetr

[@joaoc_PT]

i have a dead 5vsb rail on a lcpower 600w. Already measured up to the pri capacitor and its ok. Any advice?

[@AndrewKoala]

Pointed tips on soldering irons are about as useful as a fly-screen on a submarine. Get a decent temperature controlled iron with plated tips. [ They are not expensive ] and use a chisel tip, where you can have enough concentrated heat to easily remove components.

[@RaceLine10]

what a shame i bought a new psu, now i know i could have fixed myself, hey if the capacitor is not leaking but the top of it is slightly fat, does it mean thats its failed? i have been looking everywhere and all the others are fine. also i tried the paperclip test and the fan spin but in motherboard it doesent work :) . thanks!

[@alwaysafix]

Just needed a soldering iron for 5 mins work. If I'm doing longer jobs, then I'll dig out my temperature controlled station.

[@joaoc_PT]

I understand, but this psu is really well built (i was wrong, it is the 700w, model LC8700 v2.2). I really want to repair it, but my electronic skills (although higher than average), aren't enough to find out the component, unless i start ripping it apart and test component by component. The problem with dead 5v sb, is that nothing else on the lower tension part of the board can be turned on. Its like an 1% fail that prevents it working...

[@gajeragopalonlinee]

sir, i have an dell t3500 working station and few days ago when i start the pc its gone turn off automatically in 2-5 seconeds so..plzz help how can i repair???????

[@MrBliff123]

i have a evga mod power that my friend just bought he put he put a vga wire in a cpu port and turned it on and it popped when completed unpluged for a while and then plug it back in it will go to work but shut down is the any hope for it i cant find any fuse inside it or damaged capacitors would be a great help even for any more trouble shooting thanks

[@alwaysafix]

It's not the fuse, maybe you damaged the motherboard. You need to connect another PSU to rule out the motherboard. Good luck!

[@MrBliff123]

the computer is working have another psu in and working fine psu pluged in on is own and jumped fan will one spin for a split sec and shut down

[@500agk]

blac jack I have the exact same problem. I just got this power supply and it started up and it was good for about an hour and then my PC turned off and when i try to turn it on, it spins the fans a bit and that's it.

[@smellthecoffee5314]

Nice Video - Very Helpful - Thanks

[@alwaysafix]

Much appreciated. Thanks for watching.

[@shubhamlingwal8424]

Dear, When I am replacing condenser I forget where we is "-" or "+" side please help me for repairing my Dell optiplex 755 power supply.

[@underwebtechno2734]

there's always a stripe or band on negative and pcbs are printed.

[@alwaysafix]

Like I said before, if you make a mistake in the repair, you risk your motherboard. Even though the PSU might be worth it, you've got to ask yourself is the motherboard worth the risk? Good luck!

[@bhaskerthapa6534]

ic no tny279pn is cracked, can i use any compatible ic??

[@thomasleerriem6872]

Wouldn't it be better to check caps with an ESR-meter? There could be a problem in terms of their equivalent series resistance, without the capacitance being drifted. ESR-values are extremely important in switch mode PSU circuitry. Tx for he vid btw ;)

[@alwaysafix]

This video is targeted at everyday do it yourselfers and because they won't have such professional equipment I try and keep these videos as basic as possible. Thanks for watching.

[@thulinp]

Thomas Leerriem Agreeing with this. You can get an usable hobby ESR meter for $18 on ebay. It would detect that your 1000u cap was bad. And it's very important when reusing salvaged caps.

[@thomasleerriem6872]

The ESR-meter I use has a pass/fail-function. Since it measures both capacitance and ESR-value, it can decide whether a cap is defective or not. Even when measuring the expected capacitance, a cap can still be defective. I find such a combined ESR-meter very usefull.

[@smoothloser]

Why don't you discharge the two big reservoir capacitors before replacing the blown capacitors ??

[@alwaysafix]

I did off camera. Thanks for watching.

[@comyf5986]

alwaysafix can you tell us how you discharged it?

[@alwaysafix]

Comy F Short it out with a screwdriver. WARNING: it might spark a little.

[@ameyas7726]

alwaysafix to avoid spark, discharge using two alligator clip wires connected to a resistor inbetween (the higher value the better)...they are fairly cheap.

[@alwaysafix]

Ameya S Thanks for your input.

[@deathour9269]

Mine turns on but it only last like 30 seconds and restarts also it makes a weird sound what possible way can i fix my power supply

[@KiroVencenzo]

i have a big problem in my PC and i don't want to go and buy Power supply without make sure it's the reason my PC shuts down after several hrs like 5-6 hrs and i have A/C in da house so there's no over heating problem , besides that i cleaned the CPU fan/ GPU fan and still have same problem , unpluged all my HDD except the one i have windows on and still have same problem , i even tried to clean the motherboard and still have same problem , the only thing it's remains is installing a new power supply or install a new windows ?????????? pls help My power supply is very advanced 700Wat with big fan in the middle

[@alwaysafix]

You need to borrow another PSU in order to rule out the motherboard etc... Good luck!

[@KiroVencenzo]

alwaysafix i can't borrow just buy , because the problem appear after 5-6 hrs of use , is there a virus can do that ? or processor can cause that because suddenly when start shutdown and immediately back up on by itself sometimes restart again even without loading windows , i have doubt it's processor because it's working fine for 5-6hrs and also but my other question is what the reason Power supply could cause that?

[@alwaysafix]

TheMaster Karim In the workshop we use the process of elimination in such cases. You will have to buy another PSU. Good luck!

[@builtrodewreckedit]

why test the bulging or leaking caps you remove? I would say bulging or leaking failed the first test the visual one. Why waste more time testing them would you reuse them in any case?

[@1800Supreme]

What do I do if all the caps are good. my psu shuts off shortly after turning on

[@alwaysafix]

Flying Karapet Have you tried another PSU to confirm that your power supply is at fault?

[@1800Supreme]

yeah tried failing PSU "A" in computer "B" and vice versa. its the PSU

[@alwaysafix]

Flying Karapet At this stage I would replace the faulty PSU.

[@1800Supreme]

Yeah sucks I just got as as a warranty replacement for a PSU that lasted 5 years this one only did 5 months

[@SAMURBRO]

What if The fuse goes frequently after switching the psc on

[@TheLundsgaard]

i hope you dont mind me asking but where are you from? it just sounds like you have a slight accent ;)

[@powerzx]

Everybody speaks with some kind of accent :)

[@fungames24]

Likely South African. Just one of many dialects of English.

[@kotikoti7190]

thanks for explanations

[@tl275]

how bout new Psu not working? I got a EVGA one

[@alwaysafix]

+R ed The problem is most probably your motherboard and not the PSU.

[@tl275]

I thought so.

[@mcdonaldtshwaranang130]

Sir can you help with my power supply. When I try to switch my computer on, the electricity goes off. In other words it shuts down the power plug which provides the whole house with power.. I believe its the power supply.

[@underwebtechno2734]

there's a shortage in your supply dude!

[@fatihtasdemir7812]

mine 2 psu running doesn't. computer psu without another runs how?

[@alwaysafix]

Fatih taşdemir If your PSU doesn't work on your computer but works on another computer you probably looking at a motherboard problem.

[@STV-th2tv]

computer power supply fault finding and correctiv action good

[@rizwannasir4195]

my dell power supply is not working.all the capacitors and transistors are apparently in good condition plus nothing smells bad.but still its not working can you help me.REGARDS

[@alwaysafix]

+Rizwan Nasir Maybe the problem is the motherboard. Have you tried another power supply to rule out other issues?

[@rizwannasir4195]

YES MOTHER BOARD IS OK

[@alwaysafix]

+Rizwan Nasir If you are 100% sure the motherboard is ok, I would just replace the psu. Good luck!

[@thatpvppro1979]

Me same

[@mparwezk]

I repaired more than a dozen PC power supply, but never came across bad caps.... my chance.

[@alwaysafix]

+MParwez K Whenever a failing power supply comes through the workshop and Im talking thousands over the years, nine times out of ten it is bad capacitors. Thanks for watching and Happy Christmas.

[@donandmastercracker1144]

Hey My power supply ATX one has been short circuited and not starting. Here is how : When I opened my pc to take a look I saw nothing But when I started the pc I saw a blue sparkle and it turned off and next time I am starting it it does not start

[@Nightowl_IT]

Hi Can please rename the video to PSU bad cap replacement. Can you make a video where you explain what all the components do? That would be awesome.

[@TrendingPendingVideos]

Someone help ok so I. Got a r7 250 and a i5 4690 I getting a gtx 970 I only, got a 500w so I'm getting a corsair 750w 80+ builder series cx750. And here is problem If I get a bigger psu the 750w my i5 has a fan on it and if I get a bigger psu I'm sure it's gonna block it idk I have novatech galaxy 3 gaming case how can I tell if it won't block or to big idk what to do ? Link to case. Ignore the psu it comes with this is just the case I got www.novatech.co.uk/products/components/cases/cases/cas-408.html New psu. Link. www.amazon.co.uk/dp/B008RJZR40/ref=twister_B00I5LYCI2?_encoding=UTF8&psc=1 Card link. www.aria.co.uk/Products/Components/Graphics+Cards/NVIDIA+GeForce/GeForce+GTX+970/Zotac+GTX+970+4GB+%28Maxwell%29+Nvidia+PCI+Express+Graphics+Card+%2B+1+FREE+GAME%21+?productId=62032&source=pcpartpicker

[@alwaysafix]

Yes, it's going to fit.

[@ianosf]

I suggest put a music when you speed up the video instead of silence

[@MAGAMAN]

No. The way he did it saves me from having to mute the terrible music most people use. I wish everyone did it this way.

[@therider3939]

Mine is triping the breaker my termister blew up

[@stillgamer7553]

mine turns on but after 3 sec it turns off help?

[@alwaysafix]

+StillGamer755 “stillgaming755” Have you tried another power supply on that motherboard to rule out motherboard issues?

[@powerhmong]

nice done, but it might not provide enough power as the pc want

[@alwaysafix]

This PSU has been fitted to the computer since that day of the repair, and Im happy to report no issues. Thanks for watching.

[@rahmatjulianto898]

good perfect passable

[@alwaysafix]

+Rahmat julianto Thanks for watching.

[@dorfschmidt4833]

Switchmode power supplies shouldn't run without a load.

[@rockvillemike6062]

Whenever I replace a swollen capacitor if they're other caps of the same brand and rating, even if they test good and function, I will replace them too. They can't be far off from failing as well. And I like to raise the voltage a step or two, if they still fit, like going from 16v to 25 v. Just saying....................................................................'Mike

[@alwaysafix]

Makes perfect sense Mike, thanks for watching.

[@avinashbaraskar42]

How ATX Switching Power Supplies dc 12v 5v to converting dc 15v 9v

[@sudipkong1120]

you forgot to discharge the primary capacitors.

[@alwaysafix]

+Sudip Kong I always discharge the primary capacitors, just did it off camera. I do this for a living and you soon learn what bites. Thanks for watching.

[@sudipkong1120]

alwaysafix anyways, i have a problem with my newly purchased smps which gives an output voltage of 12 and can handle upto 10 Amps of current, that if i start up the smps with the load connected it fails to start up with a flickering sound but if i disconnect the load and start up the smps first and connect the load afterwards it works fine.( the load that i use is just a small pc fan that draws only 0.25A at 12V.) Iam not sure if it's a sign of a failing capacitor...Please Help!

[@dedskin1]

dont junk it , look at all the nice transformers and things in it u can use for other projects

[@alwaysafix]

+Pavle Pavlovic Lol, you don't want to see what my storeroom looks like from keeping things for a useful project. Thanks for watching.

[@dedskin1]

alwaysafix :) i just repaired , one of those , hope so , one rectifier cap sparked from overload . fuse did not burn ..now im getting i new one . Its an old PSU im thinking of using it as a bench PS.. like the vids

[@hotboy11452]

or just do one cap at a time

[@douglazamar8889]

it cost the same fixing as buying new

[@alwaysafix]

When I come across a problem like this in the workshop, I just replace the PSU, and not risk damaging the motherboard.

[@grengeg7373]

easier to just buy a new power supply if the money is there

[@alwaysafix]

True, but it depends on the power supply. Some PSU's cost over $100, and some might be hard to find because of their shape and size, eg home theatre pc's. Thanks for watching.