Let's fix this 𝗗𝗘𝗔𝗗 ATX power supply!

On the bench a dead - and old - ATX power supply I've decided to fix. Is it worth my time?
Thanks PCBWay for sponsoring this video: pcbway.com/g/M525r4
𝗙𝗼𝗹𝗹𝗼𝘄 𝗺𝗲 𝗼𝗻 𝗫: / tony359
𝐁𝐮𝐲 𝐦𝐞 𝐚 𝐜𝐨𝐟𝐟𝐞𝐞 𝐡𝐞𝐫𝐞: www.buymeacoffee.com/tony359
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00:00 intro
01:52 Overview
04:00 Diagnostic
05:45 Oscilloscope testing
08:05 Actual troubleshooting
06:45 Testing the outcome
18:19 Components replacement
19:47 Testing again
21:30 Fixing the fan
23:53 Load test
25:10 Outro

[@John-381]

Go chop logs.

[@tony359]

The best comment ever! Thank you!

[@jimle22]

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.

[@tony359]

Thank you!

[@powerpc6037]

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.

[@tony359]

Indeed, swapping the caps will revive a good chunk of those PSUs :)

[@Ragnar8504]

Another common fault in older PSUs (80s, early 90s) is a small (single-digit µF) electrolytic on the primary side. I haven't had that in computer PSUs yet but in several VCR power supplies (Sony and Grundig). If that cap dies the PSU does nothing at all. I suspect it might be part of the passive oscillator circuit for the main power supply and if that doesn't oscillate it obviously keeps the whole unit from working. There's usually only one or two of those caps so I just replaced them all. Really interesting to understand how this circuit works now!

[@tony359]

@@Ragnar8504 Yes, that little one is critical for the oscillation!

[@adriansdigitalbasement]

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.

[@tony359]

Yes, I definitely spent too much time on that fan, I wouldn't trust it when brand new!! That said, I have a box full of fans but I don't think I have 80mm ones or maybe just a couple. Thanks for watching!

[@gar4o555]

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 :)

[@tony359]

You know what, I thought about that circlip (thanks for telling me how it's called!) - you see me fiddling with my tweezers at some point. Eventually I didn't try because I thought I might break it. I'll definitely try next time, it sounds like THE solution :) Thanks for watching!

[@SeanBZA]

@@tony359 There is a slit in it, and I tend to collect dead fans, so keep them around as donors if I need to fix one. After all, to get it out you need to have side access, easy if you are breaking the rest of the motor, plus you need to often get extra little washers that set the float at the other end, as those also break or go brittle. Plus you get ball bearing ones, where you destroy the bearing removing it without damaging the shaft, but can destroy another to get the bearing out intact. Just a drop of oil onto the bearing, and leave to wick in, makes them run nice again, though getting it to the bottom needs some pressure applied to force oil through the top one, and down the shaft to the lower one. Needle through a spare rubber cap to provide the oil and pressure works, just press down on the cap to keep it on.

[@tony359]

@@SeanBZA Thanks for the extra info!

[@chainq68k]

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.

[@tony359]

ahah thanks! I know what you mean, I've been credited by others as "some people say that" - so annoying :) I appreciate your kind words, thanks!

[@StarDustForge]

@@tony359 It's nice to see a creator have this kind of attitude, subscribed!

[@gnif]

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.

[@tony359]

Thank you and welcome!

[@Shmbler]

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.

[@tony359]

Of course, plenty of other things to check. I think it was the PS3 power supply I fixed in another video which had VCC but it was not switching - despite all the "alarms" were not on. So in that case a new (expensive!) controller IC fixed it! Thanks for watching!

[@bitsundbolts]

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.

[@tony359]

Well, I'm sure your 5 Asus mainboards will give you an opportunity to practice :)

[@dennisfahey2379]

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.

[@tony359]

Great idea - Though I'm 100% sure I'd follow the wrong trace anyways! :D

[@Ragnar8504]

I also sometimes put the picture alongside a mirrored one of the component side, makes tracing what goes where much easier compared to constantly flipping the board up side down.

[@tony359]

@@Ragnar8504 Great idea! I'm confident I'd still follow the wrong trace! :D

[@snakezdewiggle6084]

But thats what the Continuity setting is for😆

[@tony359]

@@snakezdewiggle6084 don't underestimate me! :)

[@jim9689]

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.

[@tony359]

Thanks for the tip!

[@sherlockholmes1121]

Tony is an actual youtube tech, good job

[@tony359]

Elementary, my dear Watson :) (Thanks!)

[@sherlockholmes1121]

@@tony359 Well the fact is that when you eliminate the impossible whatever is left however improbable must be the fault.

[@AlexandroTrevisan]

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!

[@tony359]

Thank you!

[@Snowsea-gs4wu]

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!

[@tony359]

ahah thanks! Yes, sometimes I ask myself the same question: why it's only easy to others? This one was a pleasant surprise, though I like learning things and just swapping everything wouldn't have been as rewarding! Thanks for watching!

[@manolisgledsodakis873]

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.

[@tony359]

Thank you, I'm glad you enjoyed the process! Indeed it was pretty clear the issue were the caps but it would have been boring to just swap them all! Thanks for watching!

[@krahwinkel9503]

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

[@tony359]

Thanks for your kind words! :)

[@Chris558576]

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.

[@tony359]

I'm sure it's much happier now :)

[@cocoe68]

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!!

[@tony359]

No worries and thank you!

[@pepealexandre]

Learned quite a few things, thank you, sir!

[@tony359]

Amazing, thanks!

[@SeanBZA]

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.

[@tony359]

Fuyihuu caps are the best! That monitor was NOT cheap! I think it sold for £1000 back then. It was one of the best "pro-sumer" monitor you could get! Thanks for watching!

[@SeanBZA]

@@tony359 I saw some capacitors that were marked as Sanma, a cnockoff of Samwha, and some that were NItichon, a almost perfect copy of the Nichicon logo, but the caps themselves had failed while unused.

[@tony359]

ahahah amazing!

[@NewRetroRepair]

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!

[@tony359]

I definitely need a better ESR meter for sure :) Thanks for recommending and also for the kind words :) Editing these videos is quite time consuming so I particularly appreciate the comment! :)

[@rodolfonetto118]

I learned a lot! Thanks for the video!

[@tony359]

You're very welcome :)

[@imqqmi]

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 :)

[@tony359]

interesting and yes, it's a great feeling!

[@jasmijndekkers]

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

[@tony359]

Thank you Steven!

[@kwankunghkg]

Excellent Demo. Appreciate your sharing. 🙏🙏

[@tony359]

Thank you for watching!

[@lenhunter2719]

Great video, thank you, I learned a lot.

[@tony359]

You're welcome, thanks for watching!

[@pibbles-a-plenty1105]

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!

[@tony359]

Indeed - though you'll find a couple of videos on my channel where the fault was different. Those were fun to fix! But yes, let's say 90% it's the caps :) Thanks for watching!

[@general23cmp]

Great video!

[@tony359]

Thanks!

[@waxore1142]

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.

[@tony359]

That's great! For the next one I'd like to disassemble it further as others have suggested! Thanks for watching!

[@HwAoRrDk]

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!

[@tony359]

Of course, I need to source some! Thanks for watching!

[@gorjy9610]

@@tony359just don't waste money going with branded ones, "chong" or anything similar is good enough for these PSUs, it's not like they come even from factory with something better (and managed to work for years used everyday), modern ones even come without plague installed :)

[@tony359]

I tend to buy Panasonic - but I see what you mean. Those two caps in Panasonic brand would probably be a lot of money! :) I should really have two drawers: the good ones and the CHONG ones for such projects! :)

[@mesterak]

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

[@tony359]

Thank you and Welcome!

[@marstedt]

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).

[@tony359]

Well, I felt something was going to explode if I had kept the PSU on with those bad caps - but yes, I didn't test a new cap, apologies! I'll keep that in mind for next time, thanks for your comment!

[@marstedt]

@@tony359 Thank you Tony, keep at it!

[@richardaston6361]

Great video as always Ton359 👍

[@tony359]

Thank you!

[@diego.alienigena]

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.

[@tony359]

Absolutely, be extra careful. I said I am "safe" with the differential probe but you're never "safe" with 340V nearby... Thanks for watching!

[@K10driver]

❤ 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!

[@tony359]

Be careful! And I hope you can succeed! Thanks for watching!

[@Bianchi77]

Nice info, thanks :)

[@tony359]

Thank you for watching!

[@horusfalcon]

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.

[@tony359]

Thanks and welcome! There are a couple more power supply repairs on the channel, one is a PS3 one and another one a generic one. I hope you like them!

[@lmwlmw4468]

Good work.

[@tony359]

Thanks!

[@surgingcircuits6955]

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!)

[@surgingcircuits6955]

Oh, and measuring the fan's current draw is going to be added to my repairs procedure.

[@tony359]

Thanks for your kind words, I'm glad you liked the video! I use Resolve and used Fusion to draw the lines. The lines are also tracked to the PCB which moves slightly when I touch it. It's... simple once you know how to do that :) Cheers!

[@surgingcircuits6955]

@@tony359 TY!

[@David_Ladd]

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.

[@tony359]

Many others have mentioned that, I wasn't aware the fan could be disassembled! I'll definitely do that next time! Thanks!

[@David_Ladd]

​@@tony359 I use to do this to the fan in my PSU that was in my first generic AT PC case when I got my 80286 system from school. Every few years I would have to clean and lub the fan, but the same fan lived in the PSU till I finally had to get a new case for the ATX based motherboards. Ah, the good old days. :) Though this works for many fans as long as they have that small retaining wwasher/ring/clip. I normally use two small flathead screw drivers to extract the washer. It has worked well for me since the late 80's since I found out the fans were easily repairable.

[@tony359]

I'll definitely try on my next one, thanks!

[@outfield1988]

Yes it’s all about fixing.amazing feeling

[@tony359]

eheh yes!

[@tolkienfan1972]

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

[@tolkienfan1972]

I have an ATX power supply. The leads were cut, but that's an easy fix. You may have inspired me to make use of it for something. 😁

[@tony359]

There you go! :) Yes, Doom is my go-to for testing everything :)

[@gamer_5042]

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

[@tony359]

Thank you - several viewers have mentioned that. I didn’t know that! I was tempted to try to remove that white bit but I was concerned I could damage everything. I’ll definitely try next time!

[@CallumRepairs]

Great repair and fault tracing.

[@tony359]

Thank you!

[@juanjesus4976]

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.

[@tony359]

Thank you, many others have mentioned the same, I was not aware! I'll definitely do that on my next fan! Cheers!

[@snakezdewiggle6084]

G'day Tony. Another great video / tutorial.👍 Electrolytic Capacitors do not like the heat. Win or lose, every repair is an opportunity to learn.imo.

[@tony359]

Learning and having fun is the main goal of course! Thanks for watching and for your comment!

[@za_ozero]

Well, thanks for such interesting and dangerous content

[@tony359]

you're welcome! 😊

[@TheRepeatloader]

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.

[@tony359]

I need to thank my viewers as it went very close to the recycling bin :)

[@goku445]

LOve your enthousiasm.

[@tony359]

eheh thank you!

[@crazyedo9979]

Thanking the sponsor is never wasted time.😁

[@tony359]

yep :)

[@VEC7ORlt]

Sponsorblock makes sure you dont waste time.

[@tony359]

Ah, amazing! That is going to work 100%. Once the sponsor doesn't get views or clicks, they'll stop sponsor the videos and we'll all stop making videos! 100% save of time as you won't have videos to watch anymore! Fantastic, thanks for the tip!

[@VEC7ORlt]

@@tony359 I don't want to hear it for the millionth time - if you don't like it - here's a tiny violin and get a better hobby, cause adblock and sponsorblock aren't going to be turned off, ever.

[@djdoo]

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

[@tony359]

This doesn't have AT connectors unfortunately, it would have been perfect otherwise! Thanks for watching!

[@Constantin314]

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

[@tony359]

Thank you! BuB made a video about that some time ago and the link to the store is in the description if you want one! I wonder whether out power supplies can actually deliver 35 and 38 Amps, I seriously doubt it :D Thanks for watching!

[@Constantin314]

@@tony359 yeap, me too :)

[@thefirstmissinglink]

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

[@tony359]

Wishing you lots of treasures :)

[@oldNavyJZ]

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.

[@tony359]

Because I say power supplies are dangerous?

[@oldNavyJZ]

@@tony359lol, no, I was referring to the image. The cap at the lower right looks slightly bulged, which coupled with the fact it is the component most likely to fail on these, is why I'd say right away that is the issue.

[@tony359]

Yes, that was even mentioned in the previous video when I tested the PSU. That wasn't a surprise! As I said at some point in the video, I could just replace all the caps, "it's working, thanks for watching". Meh. Boring :)

[@stevenbliss989]

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

[@tony359]

ahh thanks! Now I know how to do it it's not too bad. But it took some time, thanks for the comment!

[@miscbits6399]

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

[@tony359]

Thanks, I wasn't aware that the rotor could be removed, others have mentioned that too. I think I have some graphite grease, would that be better? Thanks for your comment!

[@outfield1988]

Fantastic

[@tony359]

Thank you! Cheers!

[@planker]

Excellent

[@tony359]

Thank you! Cheers!

[@blakecasimir]

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!

[@tony359]

Indeed, it's for fun! I played with a socket 7 motherboard today, I looked at the Q-TEC and thought "nope" :D

[@mesterak]

I have few Bestec ones pulled from OEM systems and they are still working fine after all these years. I’ve seen totally dead ones though. I always open a PSU, clean it up including lubricating the fan, and do PSU tests before using them.

[@ReinMixTape]

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.

[@tony359]

Thank you!

[@SpaghettiEnterprises]

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

[@tony359]

It's called 3-1. Maybe I should have used some more plastic-safe one - not that I care too much on that cheapo fan :) Thank you!

[@stephanc7192]

Good video

[@tony359]

Thanks for the visit!

[@DonVintaggio]

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!

[@tony359]

Yes, repairing modern stuff is a nightmare!

[@AnnaVannieuwenhuyse]

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.

[@tony359]

Absolutely but it is not audible with the caps replaced - I suppose many caps were leaking and the switching frequency was just making them "sing"? Thanks for watching!

[@AnnaVannieuwenhuyse]

@@tony359 That's possible! It's also possible that the bad caps were causing the switching to be below desirable frequency or something similar. In any case, the noise does indicate a switching IC or something switching works, so it's not completely dead!

[@kendoty2463]

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

[@FireballXL55]

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.

[@tony359]

Thanks, someone else has mentioned that, I will definitely do that next time! Thanks for watching!

[@dean-ph2ww]

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

[@stoptheirlies]

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

[@tony359]

You were right indeed - I hope you enjoyed the troubleshooting process! I'll consider the input caps, they can be expensive... :) Thanks for watching!

[@davidlguerr]

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

[@tony359]

Yes, I noticed those during the "Retro PC upgrade" video - but it's nice to actually see the problem on the scope! Thanks for watching!

[@MarcoGPUtuber]

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.

[@tony359]

When I need one, for sure. Thanks for watching!

[@mariushmedias]

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.

[@tony359]

Oh, I don't trust that label for a second, this PSU will explode if I tried to pull 35A from it! :D Re. the -5V, this PSU is rated 0.5A at -5V so I guess the requirements for that line weren't a lot back then? I suppose this is why other solutions work with voltage regulators which don't output much current. I really don't know what cards need -5V though!

[@RetroTinkerer]

Hello there! The requirements of the -5 appears to be minimum, you might find Doc TB ATX2AT Smart converter page about his measurements on the negative voltages interesting.

[@tony359]

Thanks!

[@SeanBZA]

@@tony359 Not many these days, as there are really no plug in modem cards around, which used -5V for the audio path, while RS232 still uses the -12V rail. Have a Dell PC where the PSU only supplies 12V, on 3 rails, and the motherboard provides the 5V, 3V3 and core voltages from that, with a small SMPS buck converter doing the standby rail. As it only has PCI and PCIE slots there must be a tiny one only to do -12V from that main 12V bus.

[@orange_tweleve]

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

[@tony359]

Thanks and welcome! It's a basic component tester, there are many different types available. I think the original name is LCR something :) It works very well and it's very cheap. Thanks for watching!

[@orange_tweleve]

@tony359 thank you for making the video too ! I was doubting whether to buy an oscilloscope for electronic repair since most people on forums kind of discourage it saying its not very useful but after seeing your video I realised its extremely useful rather than just relying on the multimeter. Thanks for the great videos 👍

[@tony359]

There are cheap scopes nowadays which work pretty well. But BEWARE, do NOT use a scope on a power supply unless you have a differential probe - a battery-powered scope should also be ok but I cannot be 100% sure. What I am saying is that remember the ground lead of a scope is.... ground. It's not like a multimeter where you can poke everywhere. If you ground something which has potential, you make a big bang :) (Ask me how I know? :D)

[@maxtornogood]

Sometimes all it takes it a good ol' recapping!

[@tony359]

Particularly when those prestigious brands are used! :D

[@lilianapatru5933]

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.

[@tony359]

Thank you for the comment - Yes, I am very aware that that fan won't last long, though I wasn't aware the fan could be disassembled further. Others have mentioned and I will definitely do that next time! About the grease, it might be a good idea as well.

[@Ragnar8504]

With decent caps and low hours I'd honestly expect to get at least ten years out of a rebuilt power supply, if not more. It's not like you're likely to run a vintage computer 24/7 all year long like some people do with new computers and did when these were new.

[@tony359]

Absolutely, my retro gear is barely being used :)

[@JohnnyX50]

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 :)

[@tony359]

I never considered bathing a fan in WD40 :) I tend not to wash anything which has coils in them - transformers, motor coils, as I'm not sure I'd be able to fully dry them out. That said, a fan is low voltage so it should be good! Thanks for watching!

[@gregarmstrong552]

Yaayyy, no magic smoke!

[@tony359]

ahah almost disappointing :)

[@Scrogan]

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

[@tony359]

On this PSU I admit I dug into my stash looking for "cheap" capacitors but those are from some time ago. 99% of my caps are Panasonic, if possible "FR" series which are very low ESR and high ripple I think. They're not cheap but I don't see the point in recapping with cheap stuff. If FR are not available I always select something with low ESR as standard. For PSU - when I have them - I also use the Nichicon PW series which are designed for PSUs. Thanks for watching.

[@teardowndan5364]

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.

[@sveinfarstad3897]

Back to life 🙂

[@tony359]

Yes, one less for the landfill! 🙂

[@impossiblescissors]

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

[@tony359]

Oh yes, I'd say 90%.

[@numbr6]

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!

[@tony359]

Of course it was really not worth the time on this PSU - it was just for educational purposes :) I hope you can fix yours!

[@numbr6]

@@tony359 I hate eWaste, and my failed ATX PSU is in the queue to be worked on. I've fixed "so many" appliances around the house, literally saving thousands of dollars. These learning opportunities are worth the time.

[@GigAHerZ64]

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

[@tony359]

Absolutely! Thanks for watching!

[@gasparreis303]

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 ?

[@tony359]

Hard to say but it looks like the on/off circuit is fried - yes, I know you knew this already! Modern PSUs are also a nightmare to work with, everything is so crammed. Thanks for watching!

[@LuggageStardate]

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

[@tony359]

Yes, PSUs are not for everybody and getting a good replacement is always a good idea :)

[@jenko701]

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 .

[@tony359]

Of course, check this other video when I mentioned exactly that: kzbin.info/www/bejne/sKHVoGNsfcRnjK8 (9:33) The purpose of my videos is to learn and experiment though. It was pretty obvious that the problem was the capacitors but if I had just swapped them all without learning about how the PSU works, probing the ICs etc, it would have been "just another capacitor swap video" :) Thanks for your comment and for watching!

[@jenko701]

@@tony359 I agree totally, you have to be able to noodle these things when something besides caps . But man a lot of time, it’s caps .

[@tony359]

Imagine a world without capacitors :)

[@ImaginaPower]

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

[@sobertillnoon]

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

[@tony359]

Yes, WD40 is a good cleaner - but I don't recommend using it as a long term lubricant. Thanks for watching!

[@Vermilicious]

Halleluja! Another PSU saved!

[@tony359]

:)

[@stabilini]

Nice graphics showing traces!

[@tony359]

Hey thank you! I'm sure they're easy to do if you know how to use Fusion - but I'm not that person so it took me a while :)

[@helifynoe9930]

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 KZbin videos at 60 frames per second. Repair cost was about $9.95 CAD.

[@tony359]

The amount of electronics going to the landfill because of simple faults is sad. But for a non-skilled person it doesn't make sense to have them repaired as the repairman cannot charge $9.95 or they won't get to the end of the month. So we buy new. This is so very broken. Thanks for watching!

[@helifynoe9930]

@@tony359 Yes, but I am glad I have had experience in the electronics field. Each of the following broke down at one point, but all are up and working to this day. My 1976 home made speakers. They required replacement of the outer foam rings of the two 15" woofers. My 1976 Heathkit AA-1506 120 watt audio amplifier. My 1976 Soundcraftsmen PE-2217 Equalizer/PreAmp. My 1999 Schwinn 6700p treadmill. My 2000 Danby Simplicity window mount air conditioner. My 2001 Palm m505 PDA, which I still use just about every day. My 2004 stainless steel microwave oven. My 2009 Black & Decker coffee maker. My 2010 Samsung TV. My 2014 Samsung S23B300 computer monitor brick power supply. Plus a few other odds and ends have been repaired. The most costly repair was for the 2 foam rings for the woofers. Sadly my 1987 DENON DCD-900 CD player, which I have repaired before with easy fixes and still looks brand new, recently had developed an IC problem. I might repair it. Not sure yet. Perhaps you can tell that I like repairing things. LOL

[@tony359]

Friends often wonder why I have "old" things at home! :)

[@helifynoe9930]

@@tony359 Is it just me and what I see, or did my last comment vanish ?? Update. On one of my computers it does not show up if I am logged in and am using Firefox., but does show up if I instead use the Edge browser and am NOT logged in. So I checked this again on my Lenovo backup computer. Here it does not matter which browser I use, nor whether I am logged in or not, it still does not show up. Weird stuff.

[@tony359]

I can see it. It's not the first time my comments "disappear", I guess it'll come back at some point. It wasn't me though :)

[@gorjy9610]

I told you it'll be easy :)

[@tony359]

ahah - it's always easy when you know what to do (which I don't BTW!)

[@mariushmedias]

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.

[@tony359]

Oh yes, the multimeter is doing a broad average - and as you could see later on in the video 5VSB was also all over the place! I didn't check it afterwards though! Thanks for watching!

[@SianaGearz]

You have -12V line anyway so you can use a cheap linear regulator. One of classic ways to get -5V from +5V is a standard 7660 IC which is much easier than 063 since you don't need an inductor, and you don't need even any resistors, simplest IC to use. This IC comes from half a dozen different manufacturers. It's not intended for high current but it'll hold up a negative rail of an opamp perfectly fine!

[@walter7671]

Two capacitors were visibly swollen, that was the problem. Of course, replacing them without any analysis would have been uninteresting. Good job!

[@tony359]

Exactly! Thank you!

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.

[@tony359]

Indeed - I think it's because of the broken fan. This thing must have badly overheated for quite some time. Caps don't like heat at all. Every extra 10C the life of a cap halves. So running a cap at 60C rather than 40C means that the life of the cap is 4x shorter, impressive!

[@SobieRobie]

Nice video as always :) One note: there is no reason to believe the sticker on this PS. In early 2000s the orders going to chinese factory always had two field: power and power on the label. True story.

[@tony359]

ahaha - I have no issues believing you. And it still happens in many fields unfortunately. I'll pull 35A from that thing next new year's eve so I can save on fireworks. 3-2-1 (BANG) yeeeeeeee :)

[@georgenicholas5210]

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.

[@tony359]

Particularly those cheap ones had cheap capacitors - and cheap design which meant the capacitors were stressed more than needed. Thanks for watching!

[@bazrazin1]

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.

[@tony359]

well done in discovering the 3.3 sense line issue!

[@ezeicom1]

Good

[@tony359]

Thanks

[@AlForte13]

I am a pack rat so keeping the old PSU is OK in my book. I have a box full of them. Since they are getting rare its a good idea to repair them. I wish there was a place to get the exact schematics for them.

[@tony359]

Indeed - though there are some generic schematics available online which can help. Thanks for watching!

[@AlForte13]

@@tony359 yes much more than the days of sams being the sole source

[@johncherish7610]

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

[@tony359]

Yes but as I said the purpose of the video is to explore the fault and learn. If I had swapped all the caps, the video would have been short and - I think - pretty boring :) Thanks for watching!