Let's fix this 𝗗𝗘𝗔𝗗 ATX power supply! 

Go chop logs.

You did no harm to anything and really had nothing to lose by repairing it. Learning in the process is what is valuable to us anyway. Good job Tony. Enjoyed the video.

I've repaired many power supplies years ago and I found it's usually the capacitors too that fail, especially the capacitors which stabilize the DC power for the switching circuit. These are usually capacitors in the 4.7uF to 100uF range and are mostly located closeby the heat sink of the MOSFETs that do the switching. The high temperature and proximity of the heat sinks dries out those electrolytic capacitors and they start losing their capacity up to a point where they cannot hold the voltage stable anymore and the entire power supply dies and starts to whistle.

Cool repair. I like you changed your mind, old PSU are getting rare, and yes, one that can do -5V it always more valuable. Also kudos for listening to a commenter and even crediting them. I wish more YT channels/creators would do that.

Yey, Ton359 video! Thanks for making Friday more bearable! I fully support trying to fix things, that are broken, instead of simply throwing them. Great video, Tony :) One small suggestion: when cleaning fans and trying to quieten them down, you can remove the white plastic circlip on the shaft, then pull the propeller out, then clean the shaft, the magnet dust and the bearing with WD-40 or IPA, then lightly grease with silicone grease. I have found this to be the cure for loud and vibrating fans with a needle shaft design. Then its simply a matter of putting the white circlip back in the groove on the shaft :)

Awesome fix!! I would have thrown that junk fan out LOL. I actually save these P4 PSUs for their beefy 5v but also the negative rails as you pointed out.

Very satisfying to watch. The things you've learned during the repair were totally worth it. The next thing I'd have tested would have been the two TL494 outputs that switch the two small transistors that drive the base transformer. Sometimes those die as well. On the mains side of that base drive transformer there are two small electrolytic caps, typically 1uF, which are very important for driving the main switching transistors correctly. If those are dead, the main switching transistors can overheat and self destruct.

Thanks for this, I have modified quite a few old PSUs in the past to create variable output bench PSUs, but I have never understood how the low power circuit with the smaller transformer operated, makes total sense now. Glad to see someone actually do a repair by finding the fault instead of firing the capacitor shotgun at it, even if it was capacitor issues in the end. You certainly have earned my subscription.

Very nice diagnostic! I hope one day to be able to figure out and debug electronics like you do! And this ATX power supply is definitely worth to have around - just in case you need that -5V rail.

Tip for "following the wrong trace": Take a scan/photo of the board - top and bottom - and pull it into your PC - zoom in a few steps (4X) and its so much easier to trace the paths.

Thank you for the awesome repair video! I always see videos where they change a swollen capacitor and they are done BUT that never happens to ME LOL! Seeing your troubleshooting is really inspiring and gives me confidence to keep trying and learning!

Thank you for this repair! I was hopping to see it, we always have these cheap PS and we all agree that these throubleshooting is awesome!

Tony is an actual youtube tech, good job

It is amazing, me as you and many others prefer to repair instead of send to trash. I like to find a solution and repair instead of to replace, sometimes electronics, sometimes enclosures, mechanical parts or plastics from box, etc. Thanks to share this interest to maintain!!

I very much like this format. Very useful and yet entertaining.

Done a few of those, and generally replace the lot with around 1200uF 16V or 1500uF 16V units, as I can get skinny Nichicon ones, which will fit into the space on the board. Close enough capacitance wise, and usable on all the voltage rails. The standby supply I tend to go up in capacitance, and use 63V capacitors there, normally have a good number of 47uF 63V ones around, as those are a common enough value, and I use them on gate motor power supplies, where that, along with some 470uF 35V ones, are generally a quick fix on them. On a PC power supply higher value on small ones works, and on the larger ones whatever will fit so long as it is within 50% of the value also works, they are not too critical, just need a decent ripple current rating and higher voltage, and they will be better than the original MysterLee HooFlungDung capacitors that were used, because those were cheap that day, and fitted the board mostly.

Learned quite a few things, thank you, sir!

Glad you were able to restore this, possibly working better than when it was new. I did a blanket recap on my old psu, the system was working but when i changed the case i took a look inside the psu & saw loads of swollen caps.

Hey, instead of yanking out suspected bad caps you can just solder in a new one in parallel onto the old one, it saves a lot of troubleshooting time. Of course this won't work if your cap is a short circuit, but I've never seen that yet and I doubt it happens often.

You know what Tony, you're one of my favourite creators on YT. Your editing style and general attitude is great. Keep the videos coming! Also, if you feel you're going to do more power supply repairs I can't recommend a Peak Atlas ESR 70 meter enough. It's great for checking capacitors in circuit!

These ATX power supplies are relatively easy to fix. Most problems are failing electrolytic capacitors and shorted switching transistors. Some times just a crapped out cooling fan. Components, except for a controller IC, are leaded through hole parts. I"ve repaired several of them over the years so I have a few for emergency replacement in my half dozen desktop PC's around here. Considering how cheap they look they are really quite rugged and reliable supplies. After cleaning and checking wire connections and solder joints on the circuit board you are ready for a smoke test. Use a series tungsten lamp if you don't have a variable auto-transformer and AC current meter to monitor power consumption from the Line. After power up and no smoke the next thing is to power down and start looking for capacitors with high ESR (Equivalent Series Resistance). Replace any that show significantly higher ESR than a new capacitor shows. Then the next thing is to look for is shorted or open semiconductor junctions. Same again, replace those that can't pass a proper transistor functionality test. Your chance of having found what was killing your power supply is very good at this point. Good luck!

I learned a lot! Thanks for the video!

Who would've thought that cheap ATX PSUs would get some TLC! I had a 24V PSU based on the same TL494 and configuration. Everything seemed to check out except the TL494 didn't get high enough voltage just like yours. Even though the high voltage switching transistors measured good, they were bad under load. Replaced them and it was fixed! Always a satisfying feeling :)

Great video!

Great job you did Tony. Nice to see that you repair a power supply. Greetings from Steven from the Netherlands

Excellent Demo. Appreciate your sharing. 🙏🙏

Great video, thank you, I learned a lot.

Great video as always Ton359 👍

I like the way that you worked through that. I saw the bulging 1000µF capacitors from the start so I was intrigued to see how you did the entire repair. I also like the fact that you took care of the glue. That type of petroleum-based adhesive gradually turns brown and not only becomes conductive but also corrosive! I've seen many examples where it has eaten through copper tracks, resistors and component legs.

Nice info, thanks :)

I would recommend replacing those two large mains caps as well. I repaired a very similar PSU a while back and re-capped the whole thing except the large ones. But it started misbehaving again after a few months. The large caps had failed and 50Hz mains ripple was coming through on the output. The caps had leaked badly, but I didn't see it because the glue around the base was stopping it spreading. 😅 Now this no-name 'cheap' old PSU is one of the best I have. Totally noise-free output, better than another much newer one I have!

Fantastic work, thank you. Requests: Test the replacement caps also so we can see the difference (ESR). Show the output on the scope before/after (you did do some of this).

Glad your video came up in my feed. You have another new subscriber here 👍

good repair.👏👏 I have a few power supplies lying around, they are useful for things like an electric screwdriver, 12 volt vacuum cleaner, etc. I also have a box with dead power supplies that I couldn't repair. I don't have much confidence in connecting the oscilloscope to those things.

❤ No, it was not worth to repair this PS. At least in the view of price of the PS in the past. But it was worth for your channel - i know have enough seen how to safe my old power supplies. Great Job, Well done!

I have a box type fan made just like that one that the motor was seized up on. I cleaned it and lubed it. It took a while to free up just like yours. I have that fan fully functional (with occasional lubricating) for 20+ years and still going.

Very nice work. This is my first time on your channel, so I'll check in on some other videos and maybe subscribe. I have several power supplies in a bin on my workbench, and all but one of them work. The dead one is an old 20-pin ATX kind of like this one - a very heavy +5 volt rail, and might be worth the effort to repair it.

Good work.

I wouldn't have gave that power supply the time of day until you pointed out the features it has. Ill probably start paying attention to some of the older power supplies i run across.

22:40 that white plastic is removable (it has a gap that you can spread) that will allow you to separate fan blades with shaft from stator so you can clean it much better. It's pretty easy to take apart and put back together

Really enjoyed the video, thx for doing it. Video is well produced with care. Good idea to look for a schematic that uses the same controller - for advice. Clever. Loved the drawn traces and wonder what you used to draw them. Also liked that you also make a mistake here and there, and left them In the video - very helpful for learning, going to happen, and "humble is good". Cheers! (Bring Them Back To Life!)

I love the perseverance! What kind of lubricant did you use on the fan?

Nice. I like the screen in the background showing Doom. 👍

good video, it is always better to open the fans completely and clean them since dust usually remains trapped inside them, you can also add an LC filter to the inlet, which the manufacturer evidently bypassed on the PCB Old power supplies can be a good replacement for engineering students as a cheap replacement to a laboratory source, but as always, everything with due caution.

Nice repair! You can put a thermistor on the 12v power of the fan to slow it down when the PSU is cold significally. I cannot understand why they stopped putting that female bypass ieee 3pin power socket at the back of the PSUs, it was extremely practical for monitors. Old PSUs are worth repairing, strong 5V, -5V and native AT connectors are 3 good reasons. Ciao from Grecia, Jim

Just as I said it would be the capacitors from the small transformer that stopped it starting. The fan if I can't get or have a suitable replacement, you can take off the plastic washer on the shaft and take the shaft out to fully clean it.

Great video :) Thank you for sharing @tony359 On the fan I would have removed the retaining washer and then disassembled the fan and cleaned the shaft and other parts. Then used a rubber safe lube for thee rubber spacer on the shaft on the inside and under the retaining washer.

Great repair and fault tracing.

Whenever I find an old computer that's been ransacked for parts the power supply is usually the only thing left.

true, Tony, luckily i found brand new PSUs which has 38A on 5V and bought 2 of them for my lovely skt 462 PCs. hope BuB will make an announcement about the -5v project, i wanna buy one from him :) cheers, Tony, awesome video

Excellent

Good video

Fantastic

Yes it’s all about fixing.amazing feeling

Very satisfying to watch. I have a Nox Urano II 630W ATX power supply, but it never turns off, with the fan always running without being connected to any motherboard, I checked with the ohmmeter that the green PowerOn wire is in a short circuit with the black wires? How can I solve this problem ?

Well, thanks for such interesting and dangerous content

LOve your enthousiasm.

You should couple 2 of those output cables together o start the output voltages. Did you do that?

Thanking the sponsor is never wasted time.😁

Oh i got your channel recommemded because of this video. Subbed immeditately! Btw can i know whats that device that you use to check the capacitor esr and capacitance ? It looks extremly useful

Inspires me to take a look at stuff in the back of my storage.

The squeeling is (probably) normal and a good sign, as it indicates something is switching. The ramp down on the squeel is the voltage of the switched signal suddenly dipping.

I like you red tracing of tracks, thank you! :)

You saved a PSU with a obscure voltage option, so all good and totally worth doing. Lots of people are about let's save the C64 or Amiga, but there's some cool generic 90s to early 2000s hardware which is worth saving.

As soon as you zoomed in, I could clearly see some bulged capacitors, which is quite common for devices of that time period.

Hi Tony, just started to watch this video, in my experience it mostly turns out to be a capacitor, usually on the outputs or the start up supply, sometimes an output diode, they look like transistors or Mossfets, but they are power diodes. Bob. I will be interested to see what you find OH! also sometimes the startup resistor goes very high in value. Edit: Well done Tony, for information it is rare that the big mains input capacitors have to be replaced. Bob

it's always best to remove the fan rotor from the body and clean the shaft/bearing with IPA. That allows you to also check for melted plastic (bearing failure) The best lube for brass sleeve bearings is graphite, do NOT use any form of oil as it will bind and burnup eventually

Nice to see something being repaired; these days with all the manufacturers locking down hardware (even smartphones with custom firmware that prevent even replacing modules between legit identical models!) it's good to see the process of self repair a PSU, which has lots of cool uses for DIY projects.And as a bonus it was nothing buy cheap caps.Great!

I never thought I would see someone bother to repair a Q-Tec PSU. They always were noisy and unreliable before. But this was educational and that made it worthwhile. Still wouldn't use that PSU though! Those and Bestec - steer clear!

. . . I have had properly lubricated fans last 35 years and counting . . .🎉

What microphone do you use?

What lubricant are you using for that fan?

One more comment... both of those negative 5v solutions you mentioned practically use a negative linear regulator like 7905 or LM337 to produce - 5v from - 12v - as you can see - 12v is not that well regulated in most power supplies (because it's only used by serial ports where anything above around - 8v is good enough) but it's also available in limited amount, often under 0.75A of current. So those boards make negative 5v but it would be in very limited amount, if it's actually needed (let's say by an audio amplifier that needs +/- 5v on an ISA card) it may not be good enough. As for the comment at the end... I wouldn't trust it to be capable of 35A on 5v .. the label even says maximum 180w on both 3.3v and 5v combined, and 35A on 5v would be 175w but I'm not sure that transformer is good enough to do it. Also, if you look on the heatsink on the part number of the rectifying (schottky) diodes you may find out it's a pair of diodes that can do maximum 30A or something like that. For 20-25A, it's most likely fine.

It's not only about the heavy +5V rail, it's also the -5V, that doesn't exist at all on newer PSUs. ;)

I had this troubleshot and ready for remediation by watching up to @1:53 in the video. It is at this precise moment that it is obvious what the problem is.

I do this repairing for decades as my daily work, most of my computers have these cheap, chinese power supplies. After a while, you get used with them, they are so cheap to fix, I am barely use a multimeter to check the voltage. And this is an advantage; Once the bad caps are changed, the power supply will work with no problems for 4-5 years. The only thing that you will open that again is the fan that get noisy- very noisy sometimes, with big vibrations in all the computer case. Here I suggest to have more attention on the fan repairing: Just use two sharp needles, remove the white washer, take out the fan blades and clean everything inside : the magnet , the winding, Use isoprophilic alcohol, a good brush. Then, use a good grease, I found one very good that make the difference, If you use oil for lubrication , it will work but iafter one year you´ll need to lubricate again. For someone who does not know, it is a very instructive video.

For a switching supply, you should be using dedicated low-ESR capacitors.

I've got a PSU that looks very similar to your fixed unit. It came from an HP m9040n. I had a much larger/modern PSU I've put into this computer temporarily. I did the cursory look for obviously bad caps with "popped tops" and found nothing. I did try a few other easy debugging checks, but ultimately gave up on what is likely a $25 power supply. I may re-visit this PSU after watching your video. Cheers!

0:29 since you are regularly sponsored by PCBWay, perhaps they could make some Voltage Blasters by Phil's Computer Lab and Necroware for -5V.

I always give my PC fans a bath of WD40. I fill a small container just big and deep enough to allow the WD40 to immerse them then let them run for an hour. They self clean and to remove excess oil just drain the container and let them run dry for another hour then wipe any remaining excess with kitchen towel and they are spotless and good to go again. Never suffered any harm or ill effect from this so far :) Sometimes I've washed them in hot soapy water then let them air dry then use WD40 to drive out any water from the circuit board then a drop of 3 in 1 oil on the rotating shaft. That works just as well :)

I have replaced around a hundred of Fuhjyyu caps over the last 20 years in my own electronics alone. The brand sounds a lot like that most versatile word in English vocabulary I imagine the manufacturer tells its customers when they complain about poor durability.

At around 3:40, I may be wrong but it is my understanding is that the controller chip communicates via the optocoupler and not the central transformer you mention in your comment. Those transformers should be for 5V, 3.3V and 12V respectively. Thanks for the video!

Never thought about fixing one, even cheap ones can be over 70 bucks. Always worried about frying stuff even using a new one.

I do have two micro atx power supply which makes squalling noise too. Can you please tell me what is the problem? Thanks

My old backup computer, a 2008 Lenovo ThinkCentre m58p had a boot loop problem that slowly got worse, meaning it occurred more often. That pointed me to the PSU. After replacing the bulging electrolytic capacitors, all was fine again. I also replaced the other remaining electrolytic capacitors. Anyhow, despite the computer being 16 years old, it can still handle 1440p resolution RU-vid videos at 60 frames per second. Repair cost was about $9.95 CAD.

I'm convinced that a high percentage of dead electronics can be traced to bad caps!

i have so many smps's lying around most of the don't have 5v Vsb o/p, going to buy a lcr meter soon for changing my game, most of smps faults are due to bad capacitors, i once had a working smps wanted to use it as a power supply for my tire inflator it requires 8A @ 12v, i only wanted the 12v line, also kept a sata & a molex connector just in case required for cd rom /hdd, so i desoldered all wires & connected only a 12V line ps-on 5v Vsb, after that tried to turn on the ps on it would work only for 2 sec & then off, did trouble shooting checked the o/p section nothing was bad, turned out the 3.3V sense wire should be always connected to the 3.3v line, everything works great till today.

Sometimes all it takes it a good ol' recapping!

Back to life 🙂

I was genuinely surprised, how often are the smaller capacitors bad. They do not even look that bad like the bigger ones which bulge. When I was repairing my old LCD monitor PSU, all of the little ones had big ESR, which is not good for the switching nature of all the DC-DC step-downs or SMPS in general.

You can make a -5v output using a jellybean component like MC34063 or any 34063 / 33063 (first two letters are manufacturer digits, they're made by lots of companies). There's even online "calculators" that will tell you what components to use, instead of you calculating using the formulas in the datasheet. Typing as I watch at 5 minutes ... esr of 5v standby capacity could be bad, you may be measuring 5v with multimeter but doesn't mean it's ok... the meter puts no load on the circuit so it could show 5v but be actually bad.

Yaayyy, no magic smoke!

I just used WD-40 a couple hours ago to clean a part.

I've repaired many SMPS's and in the majority, the problem is always the electrolytics. Some are obvious, bulging out the top. Otherwise, check for value and ESR.

HELP! Assistance please!! I have three Cooler Master power supplies, all at or over 10 years old. A 550, 620 and 650 watt. All three still work but under load cause burps and reboots. I'm told they all need new capacitors. Is this feasible and reasonably cost effective? Can you gives me some hints and suggestions? I counted around 50 capacitors in the 650 watt one.

I told you it'll be easy :)

40 years experience with many types of power supply’s , trouble shooting tip ,use a hair dryer and freeze spray for quick cap checking . Then go to the technical stuff if you have to .

Good

In a many cases it is the capacitors that are the problem. And that should be a primary step replace them all

Where did you get that dummy load?