Repairing cheap power supplies!
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- Опубліковано 30 чер 2024
- It's easy to fix these simple power supplies with a keen eye and a few spares!
Parts
🛒 Inrush limiting NTCs s.click.aliexpress.com/e/qNR7eMV
🛒 Replacement transistors s.click.aliexpress.com/e/rB2BAAE
🛒10A power supplies s.click.aliexpress.com/e/EEu7yba
🛒20A power supplies s.click.aliexpress.com/e/JmYvRFI
Tools used (some are better versions of the tools I use)
🛒 Proxxon mini vise geni.us/vise
🛒 Knipex needle-nose pliers geni.us/KnipexPlier
🛒 Knipex wire strippers geni.us/KnipexStripper
🛒 Knipex flush cutters geni.us/KnipexFlush
🛒 Wire crimping set geni.us/CrimpSet
🛒 Soldering station geni.us/Soulderang
Product links are affiliate links - I may earn a commission on qualifying purchases (at no extra cost to you)
🎥 All my video gear toms3d.org/my-gearPlease do not attempt these repairs if you are not confident about your electronics skills. It is impossible to explain every detail in a video, so please proceed at your own risk.
🎧 Check out the Meltzone Podcast (with CNC Kitchen)! / @themeltzone
👐 Enjoying the videos? Support my work on Patreon! / toms3dp - Наука та технологія
no telling if the 20a power supply is fixed without at least putting a modest load on it for a while.
Mostly, no telling whether it won’t overheat again.
None of the stuff in a PSU this simple is particularly likely to only half-work, though.
the failure was likely due to a component faulty from the factory (happens due to wrong handling/transportation or poor qc), so the rest of the psu should be absolutely fine.
The 10A psu however had that switching bridge short out so it likely damaged the input circuitry.
Sometimes you get electrolytic capacitors drying out due to high temp. Also the PWM IC can get damaged when the power mosfets go short circuit.
Love your 3d printer channel - I have learned a lot. Thanks Tom!
You only replaced the switching MOSFETs without checking anything else to find WHY they failed? Amazing.
Cheap low quality
exactly my thought.
Its like smelling gas in your basement and just opening a window.
Yeah that's true, however mosfet is common fail part, which is destroy.over.time mainly in cheap not proper designed power supply if you want to find problem you actually upgrading 20usd power supply. ;)
Exactly
@@xcruell Actually, no. It's not like that.
The smell of gas tells you that there could be a leak somewhere. Ignoring it could be lethal. Not the same as not fixing a $25 PSU.
"Uh-oh the car doesn't start, tried turned the key twice. Well, the car is broken.. throw it away.."!! ;p
Exactly, this man seems more like a parts changer than a true connoisseur of electronics
Definitely would love to see more videos like this! My 3d printer build experience allowed me to fix my 500 dollar computer monitor by taking it apart and re-soldering the power connections. I've gotten 3 more years outa that monitor thanks to knowledge like this.
I really liked this video, Tom. Not just the content (killer, as always) but the style, the pacing, the scene editing choices. It felt very "I Like To Make Stuff" and it felt like you were really able to convey more to your audience.
+3D Printing Nerd thanks! I like the ILTMS style a lot and am always experimenting with new workflow, this one felt a lot more dynamic than what I usually do! Usually, it's doing th thing first, then scripting, shooting, editing - and usually another round of shooting after that.
True his videos are very professional. Yours are awesome aswell. Just made your fidget spinner!!!
3D Printing Nerd yeah, good video, and I have to ask if you made yourself a couple of Adam savage mic eyeglasses? :) I'm sure he's not the only one in the world that has made a pair but he's the only one that has made a video as far as I have seen :)
My boss says"wots that". I said "fidget spinner". he says "Gimme a look". I have not seen it since he took it off me !
lol there so addictive
I was convinced he knew what he was doing until he failed with the 10A model.
me too
aww, I feared that would happen.
Its easy he must check the 2,2 Ohm resistor at the base transistor
D7 slot was fitted with a resistor. Maybe something to check...
Just send the defective one to BigClive, he loves that stuff ;)
Sebastian surely he would fully repair and possibly upgrade it, but then he would blow it up with or without dynamite, just to make things more exciting.
I'd love to see BigClive fix it.
@@JamesMossR33 It's gotta go BANG !!
You gave up to easily on the 10A supply!
Yes i'm so dissapoint, Tom son!
It's likely just a dead feedback resistor or the Zener diode. Just check everything in circuit and see whether something shorts that shouldn't, or something is open that shouldn't be, and i think with 80% probability, you would have seen what the issue was. Other 20% say that you'd have to lift one leg off every component till you find the fault :(
Yes, all he did was replace the obvious, damaged components. Troubleshoot the 10A!!
Agree... Unfinished job ! The most interesting part is investigating even if it takes time. I repaired a power supply for a friend inside a RGB laser. It was the shottky diodes.
Agreed. Surprised that you didn't mention or check the Schottky diode/s as they are quite often under specified. The current rating may be fine on paper, but when frequency and temperature are factored into the equation they can quite often fail even if the rating appears adequate. It's also a VERY quick and easy multimeter test in circuit to find out and checking the forward voltage drop when the supply is on will confirm also.
Yeah, find the fault!
Just an advice: it's always better to discharge the high voltage capacitors with a 100-470 kohm resistor. This way you're saving the capacitor from excedingly high currents through it.
100-470 *ohms* does not take all day to achieve that.
Love the speed, focus, and clarity. Great vid!
Best idea ever... if you post a video asking for help, probably get very few suggestions... post a video where you FAIL and everyone is in a hurry to jump on your failure and show you how good they are by telling you what you did wrong... now you have a bucket full of suggestions to try! Love it!
Yes! That's a concept for a career on UA-cam haha! :D
One must appreciate the style and knowledge given by this guy, Really loved your VDO it is helpful plz make vdo on how to check how much ampere is giving by power supply.
Re: oversizing power supplies. I'd go much higher than a 15A supply for your 10A load. I'd opt for 20A or more likely *30A*. These PSUs will be overspecced anyway, so a 30A supply will be just about ok with 20A, but get it to power 10A and it'll run for much longer (and much cooler).
Don't believe those eBay specs because Chinese watts are quite a bit less than Western watts. *ALWAYS* use the conversion rate: 1CW=½WW and you'll have far more success buying cheap Chinese electronical goodness.
Thats a good idea. And most people seem to think that the PSU can deliver it's rated power at all times. If you put it in a closed box, like Toms lamp, it will heat up the inside of the box to a pretty high temperature (warning: possible fire hazard!). So make shure to keep in mind that rated power is usually just good for something up to around 40-50°C and in higher temperatures you have to quickly reduce the max power you can pull out of that supply. Usually that information is written in the datasheets or in application notes (good luck finding reliable data from no-name chinese manufacturers...).
I was just watching another channel where a guy wound a 10A rated SMPS up to 14A and it was still not sagging voltage. But how long the unit could do that is debatable.
Or buy genuine western PSU's, I mean, even genuine Meanwells and such aren't so expensive.
😄1 W Chinese=1/2 W American
@@SnoVVdogsPks Exactly ! Buying reputable chinese brands is like buying reputable _anything_ brand ! Playing along with the bad actors is a recipe for sustaining bad behaviour. Stop this "chinese Watts" BS @EscapeMCP!!!
Very cool LED light fixture. Have you thought about making a quick video about how you made it?
I just came across his video now. Usually when the 2 switching transistors pop the 2 resistors on the base of the transistors also pop. These are normally 2.2 ohm. This is a quick fix. I also test the power supply before putting it back in the case. Another good practice is to use a 60W or 100W light bulb in series with the mains supply when switching on. This limits the current in the event of a fault still being present. If the light bulb glows brightly you know that there still is a problem. I also do a load test once the repair is complete. Quite often the power supply works under no load conditions, but switches off under load. Anyway keep up the good work!
You are by far my favorite 3D printing UA-camr to watch. Thanks Tom.
great video! Use a little flux will improve both soldering and desoldering and allows you to use lower temperatures. You can also preheat the pcb by putting it on a heated bed at 110 degrees for 10 mins.
The first time i had to wire one of those units i had to wait an extra day to overcome my nerves, i had a nice wiring diagram but i never trust anything a 100% luckily the diagram was spot on. Thank you for making this video i'll re-watch it if needed. Have a nice day
Just starting in repairing board(77 years old) great video,thank you. 😎😎😎
Great video! And love that lamp and paint job, super clean and techy.
I would recommend caution with the heatsink pads, they most likely provide isolation between those fets and the heatsink which is tied to ground. Most fets do not have isolated tabs.
Would love to see you do more circuitboard troubleshooting videos. I like the way you explain things, and even though you might not be an electronics tech professionally…… It’s always fun for the audience to watch and learn along with you.
It’s especially satisfying for guys like me who are professionals and do this full-time, to watch smart and competent folks like yourself learn and grow in their understanding of electronics.
PS… Check the zeners and diode‘s on the supply you couldn’t fix. Probably the issue it is very common.
Always think UPSTREAM of a failed component as to WHY it failed.
Don’t replace a fuse or transistor without figuring out what made it fail.
Also a somewhat lengthy load test would guarantee their function for the future.
I really enjoyed the video!
the rule of repairing is to repair the thing which cause it to fail not faild component
yeah, but at least there is a chance that both parts are the same. If you aren't good with trouble shooting, you can always just replace things like destroyed caps or parts that have cooling that might have gotten too hot, because of continous load. At least there you can guess that the broken part wasn't killed by some other broken part.
Also a good thing to check and fix with these chiinese models is the grounding, I've had multiple ones with ground not connected to the casing..
Thanks for finally deoxidizing and retinning the soldering iron tip at 4:40 or so. LOL Good, fun repair video, thanks again.
Man I so need to do this work on my broken power supplies. The printer's been down for 6 months and I miss printing. Good work Thomas
After replacing the switching transistors, on the hot side, it is necessary to check the circuits from the transistor base (resistors, diode and capacitance).
To connect the power supply for inspection, it is necessary to use an incandescent lamp of ~ 100 watts instead of a fuse. This will protect the power supply from damage in the event of additional malfunctions. And you can use this lamp for discharging power capacitors.
when I hear the sound bite is clear, your voice is understandable and your workshop is amazing, I immediately click subscribe and thumbs up, when you try to discharge the cap that way and failed on repairing the 10 Amp, I immediately regret it.
Thomas, I'm impressed much better than when you sometimes do wiring live !!!
Great video as always. Keep the good work, sir.You are the best teacher.I have learned a lot from you 😁
Like your style and speed of delivery: no nonsense. And that you comment to discharge the caps. Would have liked more on the 10A or put a follow-up link to vid in the comments of this one. I am not a beginner, but a refresh of your logic and steps is great. Thanks. Also: Do you have a link to the ceiling lamp (very cool!)?
Thank you for showing me something new and how to repair stuff too. Good day fella.
Oh! Great, Thomas. I have one of this broken psu here but never tried to fix then. :)
I would agree with some of the comments here, a little more detail on how to safely discharge the caps is in order. Other then that, well done.
Safely for what? You or the capacitor? If you really want to do it safely then you should use a bleeder resistor. Because just shorting a charged cap out you can blow holes in the dielectric.
Given the failure modes I would have thought that they failed due to a power surge but the NTC looked like it may have been poor quality given that the bond for the lead had failed.
A few more points:
1. The mains capacitors do not always remain charged. It depends on circuit design, bleed resistor failure, and when it was last powered up.
2. A lamp is a handy discharging method.
3. It is very easy to check for charged capacitors with a multimeter.
4. Don't use tools to discharge capacitors.
-- It blows holes in the tools.
-- You should be using good quality tools and that is not the sort of treatment you would give them.
-- The sort of currents that are generated may be bad for the capacitor.
5. Never put the covers back on until you have carried out tests. If you feel unsafe without the covers on you should not be be anywhere near the tools.
6. Your soldering of the bridge rectifier was very poor. Solder joints should have nice fillets and should not be blobs. Obviously the legs were not tinning very well. What you should have done was to clean the legs back to bare copper and then resoldered it back in place.
7. You should have cleaned the thermal paste off the sil pads, especially if it was dry.
8. Whenever the switching FETs have blown there is a huge procedure to go through before applying full mains power. Too long to outline here.
9. The Faston crimp connectors were not needed in this case. All you were doing was a bench test and the terminals on the power supply had a square securing washer designed to clamp directly onto the wire. You wasted three crimps.
10. Invest in a hand operated desoldering pump (at the very least). The method you used for desoldering is tedious and puts unneeded thermal stress on the pcb pads.
soldering pumps are way better than wick. he didn't need to cut the legs if he had one... soldering pumps can last a lifetime. while wick is consumable.
The crimped connectors are perfectly fine.... it makes it look neat. sure not necessary but it also helps avoid the chance of a unseen loose wire strand making contact with neighboring terminals. No need to criticize his use of them. highly unprofessional.
Yes, you have to discharge those capacitors before you touch anything on the PCB. I had to learn that the hard way when I repaired an icecream machine.
Let's say I was really wide awake after I touched the PCB on the wrong trace.
But at least now I can make my own icecream. That's worth it.
I'd love to see more of your ceiling light. That is so cool.
Thanks for the quick overview!
Wow that's such a cool ceiling lamp!
Thanks for sharing this video, if condenser and inductor white liquid comes out, the power supply can be repaired
Nice electronics skills like cutting off the power transistor so you can unsolder one leg at a time, and also mounting the pcb on a vice vertically. Nice work.
In this case, when transistors or mosfets are burnt, the resistor connected to the gate of both mosfets also burn out. That are usually of value 1 ohm. Same case was happen with me on 12v 30amp PSU.
Check out the toroid coil connections on the 10 Amp power supply. They got broken easily and it could be the problem. I got the same led not working and no power output issues and I finally found out that the toroid's connections were broken.
It has some connections hidden in the middle of the toroid.
Very healthy and safe discharging (although not for the component itself).. I think this should have more attention
Helpful repair video 👍
I just fixed one of my power supplies these days, the chip providing power_ok was bad even if everything else was alright, so i just put a inductor on the 5v signal and make a power_ok signal myself and voila! Fixed! I wanted to replace the broken chip but heres nowhere one of these on all my power supplies scraps here.
Awesome video, as always! As a follow up video maybe you can do some upgrades to the power supply? Not many of us would know how to upgrade the power supply to better components(if it's worth it)!
+roboticsgenius totally not worth it - Meanwell suppliers aren't that much more expensive and deliver exactly what they promise, if you try to improve these cheap ones you'll just run into one bottleneck after the other.
Nice work sir
Keep up the repair contents. It's quite educational
knipex, proxxon and wera. You sir have great taste in tools. Although my love of knipex is not good for my bank balance.
A lot of these cheap power supplies don't have continuity between the earth terminal and the metal casing. I've bought a few of them, only one had continuity. Always check and if yours doesn't, just link one up to the side via one of the mounting screw holes.
Thank you, learned a lot!
I would like to see many more of these power supply repair videos but in real time please.
Like this vid. Only thing that was missing for me as a noob was the settings on the multimeter.
love the light fixture would love to know how you made that looks amazing also personally like the meanwell ipx rated i know there expensive but hey they last so you use alli express ever used digikey or mouser theres one other as well allied electronics they carry stuff all the way up to vac motors
First video I see, then went straight to your channel.. very useful stuff mane, of course I subscribed. Keep it up 💪
There's a technique to soldering..... This gentleman makes it appear easy.
thats a really cool lamp
Hi, first thank you for sharing this video, for the second power supply since the switching transistors are damaged then it is possible the the PWM controller is damaged too , try to replace the PWM controller , it is located on the high voltage section of the PCB , try to download the datasheet of the PWM controller it shows the components connected with it on a typical application , this may help to fix the issue & bring the supply to life again.
Great channel, love that LED light too
Thank you for sharing !
Make sure to also check SWISTONE soldering wick, works way way way better than the one you showed
Ever tried a spring pump to suck out the solder tin? Works like a charm.
This video feels cool!
i repaired a desktop power supply 10 yrs ago.
All i had to do was replace a blown cap.
then it worked fine for yrs after.
It's a good point to assemble aluminum cover. Sometimes when you power them, some capacitors will explode. But if it takes time, remember to put the board upside down.
caps explode if polarity is reversed - otherwise ... not really
Liked the video Tom. Thanks.
Excelente trabajo
Nice repair 😎
REALLY good video 👍
great video as usual !
The 10amp most likely needs a cap or two replaced. Easy fix. About the high voltage caps holding a charge. It is very possible it can hold one. Especially if the discharge circuit has been damaged.
I wish you mentioned HOW to safely discharge the capacitors. Not everyone knows how to do that safely. Otherwise good stuff!
But he do, at 4:00
He does it, but doesn't actually say how he is doing it. you just see him wiggle a screwdriver. I mean, I know what he did, and you know what he did, but not everyone will, and I just don't want to see anyone get a nasty shock.
That's true, had the same reaction as you initially in the clip, he could have stated it clearer.
He used an insulated tool to connect the two sides... that said, it is a huge liability to tell people how to do it. If you are at all uncomfortable or not 100% sure that you have discharged the caps... don't continue.
Oh that I agree with. So just say that - if you don't know how to discharge the caps, just stop now. Or go learn from someone else and sue them if it goes wrong. I just feel like it was a little bit too glossed over for such an important safety step. Then again, this didn't include a step by step tutorial on how to (de)solder things, so I guess some basic knowledge is assumed in the viewer.
Well done sir
neat work
This man seems more like a parts changer than a true connoisseur of electronics.
excellent video .. thx
Good Work
Well done. Cheers
For everyone looking for it: Such supplies are for example sold (produced?) by "ZJIVNV Official Store" on Aliexpress.
Meanwell Power Supplies tend not to burn your house down.
Mean Well doesn't then teach how to put out a burning house, so no points, mate.
+Ross Fisher yup.
Mean Well won't give you a reason to watch a dead PSU video ;)
I recommend that in order to be safer in the future, use genuine transistor from suppliers such as mouser, digikey. Transistors are really easy to fake. (Although it is possible that those on aliexpress are genuine as they are not a really popular model. IRF540N which is really popular for example may be fake, but that is a mosfet)
good job
Maybe next time you can make a schematic and how basically these PSU s work . Until know you did just the swaptronics and hope that it works repair . Unfortunately I m also at this stage, I would replace the obviously burned parts and hope it works . So looking forward to the next video in these series ... although I don't know how safe it would be to measure the voltages especially in the primary side .
Very useful sir 👍👍👍🙏🙏
Took a lighting hit and it fried one of these power supplies which was rated at 30 amps. It was connected to a surge protector a Isobar 4 which was turned off as the power supply. I suspect the high current traveled thru the ground. Moral of this story disconnect if lighting is in the area.
Hey Thomas, thanks for sharing this video! I have a power pack on my run of the mill 3d printer that seems to be almost identical to these. One day while my print was paused one of the smaller capacitors exploded so i purchased some replacements and swapped the old one out. Put it sll back together and it blew again! Does this seem like something would be putting too much load on the power supply or perhaps anothe faulty component on the supply? Any advice would be greatly appreciated. Luke
Good job
Thanks Thomas
should have fluxed the transformer points :) would have made them turn out a little nicer. also using 60/40 to alloy the solder would have helped a ton in removing it. just some tips if you didn't know, but i'm sure you knew!
Tom has an irrational disdain for lead.
But using it to remove is very simple. Using the tin solder after is just fine.
Nice video.... ive a little question (before ask, i have not much knowledge on electronic... ), ive a power supply that just shut off while it was charging and of course when you plug it in doesnt start at all... my question is what should be checking/looking for with the multimeter to try to find a way to fix it...
hope can help thanks
once again good video
Please only teach things you really know.
This is too dangerous.
You replaced the blown mosfets, without caring about WHY they blew. Thats basically the best example
Always just use an old computer PSU, its cheap (free most of the time) and delivers more than enough for 3.3V, 5V and 12V. Sometimes even 24V.
Frank true but you need to put some load on the 5 V and to know how to start it so not plug play like these cheapo Chinese ones
Well not really, i've been doing this without an issue with many of them. Maybe a few of them have a couple of safety features but hey, its free!
You don't really need a load on the 5V line, just need to short PS_ON pin and COM and power supply turns on.
Or just buy a good quality, name-brand PSU that fits in the same location as the original supply in your printer, has a believable output power rating, and has proper safety and EMI certification testing done.
A genuine Mean Well LRS-350-12 supply can be had for $32 USD from Mouser, Future, Jameco and a bunch of other electronics suppliers - www.findchips.com/search/lrs-350-12 - this is the supply I recommend to everyone.
they're pretty simple to jump though, you just have to bridge the green and any black wire, you can even buy pre-crimped and ready 24 pin PSU jumpers that you just plug in.
I got a 40 amp 12 volt version to power a 2-way radio repeater and sitting idle (muted receive mode) with less than 2 amps draw the supply failed in about 4 hours. Even when the radio is transmitting at it's 75 watts, 40 amps should be more than overkill.
I liked this video because it was not too short or excruciatingly long. The question that always surfaces for me is why don't they somehow design diagnostic codes into this systems. It would be nice if a fault code or something would appear that would clue you in on the problem. Without this, then one has to go through detailed troubleshooting and analysis to locate the problem.
somehow these supplies tend to multiply and you end up with 3 or 4 lying around xD ...and those vices are very very handy for all sorts of stuff....I have a 15$ cast aluminium aldi one which has worked great.
It's a useful video if you have a visible damage.
...and while I'm here, I have question: one of my similar power supply has 100~ volts in the casing under load, any ideas how that couls be repaired?
The noise from the MOSFETs is getting through the decoupling caps blue ones ...just a guess tho
man, that lamp! so sick! You don't by any chance have some documentation about your building process there?
+Jocobes it's a project from before I was making UA-cam videos. It'll come down soon anyways, maybe that's a good opportunity to document it.
very good video. Could you tell me the values of the transistors of the second source that you repaired because I have the same source but a transistor exploded. Thank you so much