This 700W ATX PSU Blows Fuses / Trips Out The Mains. Can We Fix It? SMPS Power Supply Repair

Here is a 700W ATX Power supply that trips off the mains as soon as you plug it in and switch on. What can be causing this problem and can we fix it?
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Richard

[@Catstorm99]

I used to work in a repair workshop for 10 years and we had the Fluke 70 series. I really do miss the single chirp for a diode junction. The Unit-T UT61E+ does have this feature the UT61E does not. Darren Walker reviews it. Search for "All New UNI-T UT61E+ Multimeter Review & Teardown!" 12min mark he shows the diode chirp 🙂

[@richardpeters6773]

Hi Richard great videos I have learnt a lot. Ever since you showed how the fluke operates on diode mode I have been testing various meters for this feature. I found an old AVO Megger instruments M2006 multi meter that emitters a pulsing bleep on diode test and a continues bleep on short circuit. The meter had a LCD fault which inspired me fix it. On De-soldering tools I have found the LUXIANZI 40w hand held tool works best for me. I Just need to remember to point the nozzle away before releasing the button or it sprays the solder all over the board.

[@carloca71]

The proximity of the wires may be to have a version with no PFC where they wold put a jumper, if it makes sense.

[@peternotpeter]

I'm glad you're doing these "blowing fuse" videos, I have an amp that immediately blows fuses and haven't been able to repair yet, so I'm learning your tips and tricks. it's not that easy to find shorts, but I will attempt it again, Thanks Richard.

[@budgiefish]

Very good comment about being complacent around bulk capacitors not being charged if there appears to be a dead short on input - thinking about this, if the MOV which is across the line failed in such a way to allow the cap to charge then short out - the cap will remain charged until bleeder resistors discharge (if any). Of course a MOV may be expected to expire catastrophically when it's failed, so if the MOV shorts permanently then the longer time passed since the fault originally occurred could mean the cap will be discharged through time, but if the MOV is in a position where its voltage protection characteristics come in at a lower threshold for whatever reason (think of it acting like a 180V RMS MOV on 230V instead of 260V RMS), then there's still an amount of time during the ac waveform where it could charge the capacitor... Maybe, maybe not but maybe is enough to warrant the check to be sure, IMHO :) Not sure of any other potential failures that could result in a cap being charged... Clearly any short fault downstream of the capacitor will result in no capability for the cap to charge, but we don't know that at first opening :)

[@chris_hertford]

Learning loads thanks for the videos, can't wait to see some follow ups when parts arrive!

[@mikasa1641]

The Brymen BM78x Series has a diode mode with audio feedback. BM786 from EEVBlog is the most popular one. Not cheap with 170€ but compared to fluke not that expensive either imho

[@mart43]

I am lately really enjoying these repair videos keep them coming.

[@LearnElectronicsRepair]

Thank you very much for your donation to the channel, it is very much appreciated 🙂

[@khx73]

Love your SMPS repair videos. Thanks Richard!

[@JrManPT]

Regarding the beep on diode mode, I found a list on eevblog's forum: A continuous tone for a short and a lone beep for a good PN junction: Fluke 289 287 87V 233 179 177 175 117 116 115 77IV 73III 83 110(Old USA model, presumably 111 and 112 also) 12(Old, presumably the 11 as well) 27/FM, UNI-T 61E+ Keysight U1233A U1232A U1273AX U1273A U1272A U1271 U1281 U1282 U1241B U1242B A continuous tone for a short only: UNI-T UT61E UNI-T UT71 UT181A (adjustable mV threshold) Gossen MetraHit 29S 28S 26S/M (adjustable mV threshold) Hioki DT4282 DT4281 DT4252 DT4253 DT4256 (adjustable mV threshold and LCD red light) Voltcraft VC890 VC880 (adjustable mV threshold) Appa 305 (adjustable mV threshold) Protek 608 (adjustable mV threshold)

[@LearnElectronicsRepair]

Thank you for this list, though it can't be complete because my Fluke 79 also does this and it isn't even on eevblog (the leading experts in this field?) list, But regardless of that strange omission, this feature is totally necessary in my honest opinion and this is the main reason I use my Fluke on most videos. Though when I need to measure uA or uV, then the other (cheaper) ones I have are better for that so I grab them. To all viewers, this is a very useful feature when it comes to electronics repair, go find a new/used meter that has it and you will never want to use anything else.

[@justmc62]

@@LearnElectronicsRepair I use a Fluke 189 - It also has this function and I don't see it listed . My older Fluke 81438 also has it.

[@adambradley3284]

Reminiscent of Ringo on Thomas The Tank Engine, Richard explaining the Fan Controller on the Red Wire.

[@xyzconceptsYT]

Love your methodical work! 👍

[@davesdigitaldomain]

thanks Richard really enjoyed the video. In a previous video you mentioned a sense resistor, when the opportunity arises in a future video could you please elaborate on how the circuit works

[@LearnElectronicsRepair]

Yeah I can, thanks for mentioning it

[@Dutch_off_grid_homesteading]

Heya, oh wouw 49/49 watched the hole playlist and learned so much to bad it is over for this playlist but I saw you have more playlist's so gone watch them now and see if I can learn even more

[@envision546]

Ensure that capacitor is discharged before testing. May damage your instrument

[@andycrask3531]

Hi, Recently got into your channel so doing the obligatory new channel binge. Got a problem with a Makita dab site radio. It just stopped working I've checked that the PCB has power to it and it does. Not sure on next steps I don't expect a step by step as you don't have encyclopedic knowledge on every PCB ever made :) Keep up the good work keeping ewaste out of landfill.

[@vincents.3996]

Another great repair video, thank you! I see that you order many components from Aliexpress, which makes me a bit nervous. I have had so many fake parts from there that I hesitate now to order semiconductors from there, except for parts from chinese manufacturers. I ran into trouble with fake transistors, fake linear regulators which where totaly out of specs or fake OpAmps. These parts "sort of work", then fail miserably as soon as you approach the maximum ratings or as soon as you test the thermal shotdown that there are suppose to have (but have not!). Don't you have any problems with the parts you order ?

[@LearnElectronicsRepair]

Well possibly because I order mainly generic low cost parts for repair, which are readily available and not worth faking. or more likely because the parts I order are to replace faulty components which are not being pushed to to a level approaching their maximum rating because the circuit designer left a good amount of tolerance when they selected the original component, they mostly work just fine. To be completely honest, on three occasions I had problems with replacement parts from AliExpress. On one occasion I had some replacement high voltage (and high uF) capacitors for a Class G power amp. the original capacitors were rated at 100V and the amplifier HT rail ran at 95V. The AliExpress replacements couldn't handle it and on testing broke down at 90V so I had to order elsewhere. On two other occasions I ordered MOSFETs to repair Amplifiers and the Source/Drain terminals were the reversed. Both times I got them to work with a bit of inventive soldering rework, and then they went back out to the customers and worked just fine. So IMHO 98% of the stuff I order from AliExpress works just fine, 1% requires a bit of inventive thinking and the other 1% works, but not for the specific application I intended. Even the not quite 100V capacitors were quite useful for other repair work. Clearly you have a different experience of this. why not post some more detailed information?

[@gorjy9610]

@@LearnElectronicsRepair best way to avoid bad parts there is to avoid cheapest sellers and shops with just bunch of random numbers as names :) I did most repairs in my life with parts from AE and even if number of these are quite small compared with any professional repair shop fact that I still didn't have a single case of another breakdown to me mean that parts from there can't be that bad as people use to think.

[@davet3804]

I have had no problem yet, in fact I recently ordered a capacitor meter with auto ranging (fed up with turning the range dial) and when it came it was a newer model and measured esr as well! So no complaints from me . Half the price of Amazon for upgraded gear!

[@LearnElectronicsRepair]

@Mr Guru I've not had these problems really. I did have one seller send me an updated version of a POST Analyzer, I wanted the earlier version specifically and asked them to confirm the one in the pics on their shop page was the one I would get. They did and I didn't. The seller wasn't inclined to help (we sent you an updated improved version) so I filed a claim for incorrect item sent with AliExpress. After a bit of mediation they offered a 50% refund, which I accepted. I then sold the item they sent me, nothing wrong with it, just not the one I wanted, correctly listed on ebay and it sold for more than the other 50% of the price I originally paid. As far as I was concerned that worked out pretty good for all concerned. In the case of Mosfets or something (I had an order for some LM339 and LM723 a couple of months ago from one seller. The package arrived but contained the LM393 and some other OP-Amps instead of LM723) Because the cost of the wrong parts was under €2, I didn't bother. I just kept the parts they sent and ordered what I actually wanted from someone else. In that sort of case I don't think it worth the hassle.

[@vincents.3996]

@@LearnElectronicsRepair More specifically, I have ordered a bunch of different very low dropout voltage 5V regulators from different vendors (these where not available from Mouser nor Farnell at the time). I think there where LM2940 and some other number I do not remember. They all worked as regulators, but not a single one was LDO at all. Also, I ordered some PWM controllers (UC2843). I received a bag of 10 chips, all different from each other. From the ten, only 2 where showing the expected VREF voltage on pin 8 ! Also, a recent video demonstrated capacitors which exploded at a voltage below the specified voltage. Don't take me wrong, I love AliExpress and I order a lot of things there! It is just that when I spend a lot of time repairing a device I would be sure that it will be good for a long time after. I know that some voltage converters sold on Ali have a fake controller and also that the cheap Arduinos have a fake Atmel MCU, but for those I did'nt encounter any problems using them!

[@waylonj4078]

Great Video. Maybe someone had the fan turned OFF or the Fan doesn't work. Caps went bad from over heating. Wires baked until they wont even bend. Looking forward to seeing part two and see if it works. Thanks for making these Great Videos. ALSO... In one of your recent videos you said you have a new mike. In that video the audio is a lot sharper.... Unless I'm wrong. :)

[@2DSwagGod]

yes my brymen bm785 beeps on diode mode. Great multimeter

[@LearnElectronicsRepair]

And continually bleeps on a short, in diode mode?

[@2DSwagGod]

@@LearnElectronicsRepair yep. I think theres some reviews about it if you search bm786. It's basically the same multimeter but with a temperature measurement as well.

[@sg_electronics]

UNI-T UT61E+

[@davidrobertson1980]

Mmmmm Richard you said you were putting in a circuit diagram link for that 200W ATX supply - don't see it :D

[@shanebarnes4622]

Cant wait for part two!

[@parapos]

my 20 year old YF-3502 DMM does this, a short beep on diode mode but also continuously beeping when probes are shorted (still in diode mode) I like the kaiweets km601, but after a week I don't get any readings anymore at all, its either 0L zeros or auto....... any help or pointers to fix this would be great.

[@fredfabris7187]

My 2 fluke meters act like that and is a good feature

[@daz41262010]

awesome job once again Richard :)

[@HeavenlyPress]

This channel is goated

[@LearnElectronicsRepair]

Oh, like wow! 🙂

[@GeorgeChristofi]

I'm another fluke user, I have 2 87 mk2 meters as well as various others

[@deliriumcode]

In this case, when you suspect some component blow because of overload - is it valiable thinking / option to integrate a new component (in the same package) with higher spec's? (ideally from the same manufacturer and series)

[@getmefix1921]

You should always replace it with the same specs. If you put in one that can withstand the overload and not blowing, other component (or components) in the circuit will break because they can't handle the overload.

[@Shmbler]

I recently fixed an ATX PSU with a blown primary side. Bridge rectifier, switching transistors and caps/resistors in the base driving circuit were all shorted and/or burned up. I replaced them and repaired the burned up traces but it still wouldn't start up. It turned out the two small 2SC945 transistors on the secondary side that drive the base transformer were damaged. They both did show the two expected diode junctions in circuit so I assumed they were ok. But after desoldering, the component tester reported "damaged or unknown". In addition to the expected diode drops, they also had voltage drops in directions they shouldn't. Replaced them and the PSU works. I did not expect a primary side short to blow up both of these transistors on the secondary side.

[@andymouse]

Cracking tutorial.... cheers.

[@gordthor5351]

I have at least 10 meters and not one of them have the diode beep. Here we go again..... I need to buy #11. It's just so handy to not have to keep looking at the meter. Also, you can go from checking diodes to testing continuity without switching the meter.

[@LearnElectronicsRepair]

I must admit, it is an extremely useful feature 🙂

[@gordthor5351]

@Mr Guru Where did I mention the meters were "cheap snot boxes"? A few are decent clamp meters, which can do things that your precious Fluke can't. At least 3 cost more than your over priced Fluke and have many more functions and are just as accurate. The rest are cheaper, but still have way more functions than your fluke model, other than the beeping diode mode. Dave Jones did a video about why Fluke meters are way over priced. You should watch it. I have seen cheaper meters with the beeping function. Fluke isn't the only meter to have this function. Unless you have many fluke meters (like the US military) of which you need regular, guaranteed consistent calibration (not necessarily perfectly accurate, just consistent across all fluke products), you won't benefit from paying the high price. But you did pay for it and it is a substantial amount of the price. This is what happens when you don't know why Fluke meters are way over priced.

[@gordthor5351]

@Mr Guru What "fancy functions" are you talking about? You are embarrassing yourself with all your presumptions. One of my meters has a dwell setting which any "real tech" would know is necessary to set the dwell on points. How are you going to use your "brain" to read temperature? How are you going to test a capacitor with your brain? What about frequency? People with a working brain would use a clamp meter to test current in certain situations. Cutting a wire to test current is not using your brain, if a clamp meter is the right tool for the job. I could go on and on about useful functions , but it's obvious that your "brain" doesn't understand that certain functions can not be measured by your brain. I never claimed to be a "tech" anyhow, so even if it was relevant, you are still just presuming way too much of which you can't possibly know and clearly don't know. You aren't the arbitrator of what constitutes a useful function on any tools other than your own. Because you don't know jack sh!t about the lives of others.

[@gordthor5351]

@Mr Guru The only thing that is "obvious" is that you don't know jack sh!t about why, where, how, or what meters I have. If you think one meter that can't even measure current (Fluke 12) is enough, than good for you. A bare minimum of two meters is needed to measure voltage and current at the same time. I already explained that some of my meters have specialty functions, so it should be obvious to you at least why I have half of them. If you need to know why I have the other 5, it's because at least one of the first ones I bought didn't have a bale like your Fluke. Which I find to be utterly useless when laying flat on a bench and I can only see reflections on the display. Maybe I want a meter in my truck for work. Maybe I want to have a meter out at the cabin. It's nice to have a meter handy in my shop. I have a few meters in my electronics lab. Is that okay with you? The only reason I am taking the time to demonstrate how wrong you are in your plethora of smug presumptions, is in the hopes that you might learn and stop doing it to others. No one wants to see your smug "LOLs", or pathetic presumptions. Especially on a channel like this. Go politics for that crap.

[@gordthor5351]

@Mr Guru I didn't delete anything. Check yourself, you have a habit of prematurely jumping to conclusions.

[@supercomputing942]

is it safe to Change the 10v caps on the 3.3v and 5v output rails with 6.3v capacitors? i wonder why the manufacturer put 10v caps on 3.3v and 5v output rails instead of lower rated ones? is it safe to use 6.3v caps instead? surely theres no spikes on the outputs to justify needing higher rated caps like 10v or 16v on just the 3.3v and 5v rails?

[@davestake44]

Great video as usual thanks

[@idiotwithasolderingiron]

That seems to be a Fluke feature. Only my Fluke DMMs do it that in Diode mode. Didn't know i had that hidden feature.

[@geoffedwards189]

Great user name! It describes me! 🤣😂 Best wishes.

[@jamesmackie6641]

Is it actually worth repairing a Atx power supply as they are £40 new. And is it me but the second yellow capacitor 470uf 200v looks bloated. Time stamp minutes 10.00

[@robertwilcox237]

I'm pretty sure you said you'd put a link to the schematic in the Show More area of this video. I wanted to down load it to be able to follow along as you talked. However, I've found all kinds of links to products, etc. but can't seem to find a link to a schematic. Did I miss it?

[@Silverlion49]

It only makes sense to the "engineer" who designed the board layouts. Wires, extra parts, extra complexity - it all comes down to "money' - a good layout design would save the techs that work on these time, effort, and minimize headaches, etc.

[@surgingcircuits6955]

Another great video. Thx. Q) Do you know how much power a e.g. 500W PSU w/PFC is saved vs a one without? Cheers.

[@fredfabris7187]

Do you have good luck with semiconductors purchased from AliExpress? I’d be worried about counterfeits.

[@arado240dd]

Where's the circuit diagram I can't find it

[@emailfilters]

3:32 - Since this is not from a Macintosh, Apple is not the answer to your question. 9:53 - Is that cap bulging?

[@jamesmackie6641]

Also where is the best place to get circuit schematic diagram is there a best place or is it just a case of searching the net

[@marcellipovsky8222]

Hi Richard, I am just curious, did you check the big caps later? It looked to me like the one in the middle of the board was more bulged then the other.

[@garypoplin4599]

49:48 - You have a third bad cap between your fingers here. I see a bulge on that one at the edge of the board you’re touching. 51:44 - It must have be the lighting creating an optical dillusion. That cap looks ok in this shot.

[@geoffedwards189]

Hi Richard, another great video thanks. Am I correct in believing that "hot ground" is the neutral on the AC side? Thanks.

[@geoffedwards189]

@Mr Guru Many thanks. Aha! On the DC side of course! I was only 1 diode away from being right, but still very wrong. Lolol That's why I am extremely cautious with high voltages. Thanks again.

[@geoffedwards189]

@Mr Guru Well there is one waiting for all of us I guess ..lol.. No, I do know my limitations and always err of the side of caution, That is why I ask questions. I am not a young man and take safety more seriously now than ever. :)

[@unintendedperson]

Join the discord of this channel. There a lot helpful member in our forum

[@geoffedwards189]

@@unintendedperson Thankyou Priyo. Actually I joined just yesterday and it looks great! My experience in electronics has been mainly in electric guitars and guitar pedals, with only a basic understanding of the componentry involved. Since joining this channel my knowledge has doubled at least. The more you learn the more you realise you don't know! Best wishes. 😀

[@stargazer7644]

This is great from a teaching perspective, but not from an economic one. He's got over an hour in this already, and he still has to put it back together and test it. A 700W PFC ATX supply is $59 new. Sadly this is why nobody fixes stuff like this anymore.

[@geoffedwards189]

It comes down to available time vs. available money. Also the value of education. I would happily invest a couple of hours of my time in an attempt to repair a power supply, even if I had to buy a new one in the end. Hey, I have just invested an hour of my time watching SOMEONE ELSE repairing a power supply lolol 🤣😂 To each their own. Best wishes.

[@stargazer7644]

@MrTGuru A Thermaltake Toughpower Gold with a 5 year warranty?

[@stargazer7644]

@MrTGuru You were saying it was a very cheap and nasty one. The $59 is for a Thermaltake Gold. FFS, ok, $119 then for the Platinum. Seriously, that makes little difference. It still isn't worth the time to repair it as a business.

[@stargazer7644]

@MrTGuru Apple can afford to play those games because of the ridiculous prices they get for their products - that kind of specialization is expensive. Your $300 Walmart TV manufacturer is not going to do that. And I don't think electronics are getting more complicated just to make it hard for you to repair. Consumer devices are generally made as cheaply as possible. There's nothing extra in them that would increase the cost. They want that money in their pocket. TVs today have far lower component count than they use to have, even though they have far more features and functions. The problem with spare parts availability and repair documentation is due mostly to what I said earlier. Nobody fixes these things because it isn't economically feasible. There's no market for buying one piece of the specialized chips - they want to sell 100,000 to a Chinese assembly line. Joe fixit at home working on his busted $300 TV isn't going to be able to change that.

[@theshemullet]

What do the holes that say cx+ and cx- do on the capacitor?

[@theshemullet]

Also at 38:25 is the right yellow capacitor in the row of 4 bulged?

[@theshemullet]

Ignore that. You caught it later at 45:01.

[@jorgeandrade20]

At 15:17 you add solder before removing the capacitor. What's the benefit of doing that?

[@LearnElectronicsRepair]

I add leaded 60:40 lead solder to the original unleaded solder joints, It forms an alloy with a higher lead content and makes it *much* easier to desolder, and even more so with SMD. Try it 😉

[@jorgeandrade20]

@Learn Electronics Repair I'm new at this so thank you for the tips. What's the temperature of the soldering iron set at?

[@getmefix1921]

@@jorgeandrade20 probably 60W

[@richardhalliday6469]

A little bit left field - what is Corona guard.SL displayed in your front window ?

[@LearnElectronicsRepair]

SL in Spain is the same as LTD in England (and CORP in USA?). It is the name of my limited liability company.

[@stargazer7644]

@@LearnElectronicsRepair LLC in USA

[@lrdisco2005]

You can apply logic to the functionality of Electronics, but not their design. Not saying anything else.

[@LearnElectronicsRepair]

And there is probably no need to say anything else either..