12V 5A LED switching power supply - with schematic
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- Опубликовано: 8 сен 2024
- Today I tested a 12V 5A 60W switching power supply that cost me only $3 including shipping from China. The listing says it's for LED strips, CCTV and LCD monitors. The actual current capability is only 3.5A and some parts are underrated. The PCB board definitely seems repurposed. It looks bodged, but I have seen much worse SMPS designs :). This one has a proper fuse, EMI filters, very good isolation distance on the PCB and safe X2, Y1 capacitors. I managed to reverse engineer a full schematic of it. I also explain in detail how does this switching power supply work. One of the viewers helped me to identify the control chip as XN1049 (thanks!).
Autopsy of the switching transformer:
• 12V 5A Switching Trans...
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Sir, I can only say that your wire stripping skills with those pliers are equally amazing & impressive. Extra points for the dodgyness of using the wire cutter of regular pliers for stripping.
i learned more from youtube than my 4 years of Electronics and Communication Engineering,Thank you Sir
Awesome wire stripping skills man
DiodeGoneWild doesn’t need a wire stripper. Extremely fast AND accurate.
After finishing a 5 year electrical and computer course, i am still freshman watching his videos.
Excellent! There is no other RUclips channel that does the explanation this good. 👍
I beg to differ, take a look at bigclivedotcom
I think DiodeGoneWild still explains better!
@@jaywenden1939 Diode is an electronic engineer, clive is an electrician.
Damn you are good with those schematics. That would have taken me over 4 hours to do and lots of frustration.
How long do u think it took him? they guy worked hard on that schematic.
Umm with the power of video editing [jumpcut] think again.
He is fast to draw a schematic
If they didn't overrate it and advertise that it is repurposed on the eBay page then it might not be so bad. Also props to you for making such a huge schematic. It is probably from a laptop power adapter or something, at least you can tell the original manufacturer made good quality power supply.
Dany your reverse engineering skills and knowledge are truly outstanding.... thank you so much for sharing your knowledge it is really valuable info for people who want to learn and is so appreciated
I laughed at the flying resistor part :))
Resistorgonewild
i did exactly the same lol
Dodgy bodgy
😂😂😂
Well for $3 you did get a nice box and some good active/passive components for other projects.
douro20 Exactly
Or a 3.5A Power Supply witch is nice fort this Price! :D
Actually I think the manufacturer might just put a recycled circuit board from another disposed proper transformer into a box and randomly soldered the connection. A lot of Chinese fakes are done like this.
Big isolation gap on the back of the PCB but the heatsinks bridge the primary and secondary sections on the other side and just have insulation tape for isolation.
6:14 - Impressive work sir!!
yes it is. Just amazing.
Your reverse engineering is amazing work. How long did that take?
LOL "flying resistor"--epic. very good circuit analysis
Wonderful explanation. The chip is most probably a SG6849, a PWM Flyback Power Controller.
Very nice analysis of the board/reverse engineering of the schematic, and good explanation of the fly back converter topology.
No Words
2 years later your video is still a source of knowledge. Just need to figure out how my power supply varies and
what controls the voltage. The PSU is putting out 20v for an item with an 18v max input.
Need to figure out what to change to drop that, without resorting to an external dropper, but it needs to handle
5 amps. Far more components that your power supply, shame about the output voltage. Thanks.
At 4.09' a dodgy bodgy! Lmao😂😂😩😭😂😂. I just love this dudes accent, and his skills are second to none. The right mix of Information and humour. Well liked over here.🙂
"It's a flying capaciterrrrrrr!"
No its flying resistöör
@@null7969 and dodgey bodgey 4:08
@@HighestRank XDD
@@null7969 öõäü? Estonian?
@@cuf_ Finland
Idk how yt alogarithm work. I watch electronics for quite sometime now. To see how inside of these stuff thing work. And just discovered this amazing video a while ago. Really nice stuff to learn how electronics work.
You just did manual PWM - BY DEFINITION! You rule, that shows creativity and capability to think outside the box or globe or what ever other shape you're ever faced with =)
I just have 2 laying around and i used one to power my HV SMPSU . It blew up in flames! Fireworks!
If you dip a cotton bud in turps and run it around the perimeter of the join on the casing, you can pull the case apart easily.
today i land on this youtube channel and boom all my problems are solved thanks so
Second channel: "The Flying Resistor"
Really nice! You have had quite hard work to do schematics and also explain everything. Thanks!
To disassemble similar BP, I use this method - I dial acetone or solvent into the syringe, I spill the seams carefully and on a little and then I try to disassemble the knife. If the first time does not go, I suture again. Usually 2 -3 times enough. Sorry Google translator.
Very glad to see you are not just believing in what the label reads “says “ thanks
Keep up the great work
1) As for voltage drops under significant currents I advise you to measure not at the jack but right on the PCB contacts. Reading may occur much better. Very thin output wires lead to additional voltage drop :-( Thin wires is usual situation for cheap chinesse PSU.
2) Electrolythic capacitor 22uF X 400V has too low capacitance. AFAIK there is empirical rule: this capacitance approx. equals to output wattage. For 60W output that capacitor must be about 60uF. If not we'll get great ripple over output DC
It seems the PCB was taken from some other machine and placed inside a new box to sell as new. Cheap Chinese PSUs are generally repurposed. I even got used fans, sold as new.
thank you sir for explaining how a flyback topology works! this explains why a power supply (like a monitor inverter board) will pulse on and off if there is not enough capacitance on the output (because of dry dead capacitors). after the mosfet first turns on the transformer is pretty saturated, when it is off the voltage on the secondary goes through the diode to the output and only has a small current flow (no capacitors to take in the current). at this point the core is still mostly saturated and when the mosfet turns back on the inductance is really low and the chip sees the high current and shuts down.
Absolutely fantastic! Absolutely one of the best I've seen on RUclips. I'm learning so much from you. Thank you very much.
That schematic man! You're awesome!
U are so good dude u know what you are doing though u have nice funny accent hh best job
Nice schematic and explanation. Here is a useful trick. I use switching supplies like this in my PV solar system that has a 50V dc BUSS. Many of these work down to voltages below that at very reduced current which is fine for an isolated high side FET driver. The 3 resistors to pin 5 can be reduced if the supply flashes or has trouble at lower voltages.
What if the supply does not come on at all
@DiodeGoneWild
You can open cases like this using hammer and kitchen knife. After a few hits it falls apart pretty nicely without damaging the case, so you can glue it back...
I can listen to that accent all day long!
After watching so many of video from this guy, I noticed that some of the electronics parts (not all) bought from China are of extremely poor quality (Aluminium wire inductors, recycled transistors and fake power rating on several devices). I will definitely spend more money to buy proper ones in the future.
Nice job. One of the best circuit learning channel. Please cut the wings of that flying resistorr
Watched this video yesterday. Coincidentally, just an hour ago, the power supply in my home-built living room lamp blew up, and as I just found out, it's exactly the same type! Took it down from the ceiling immediately - the power supply was very hot and dripping electrolyte through the seams of the case - the tank cap failed and released the magic smoke. Now it has to stay outside on the balcony so it doesn't stink up my apartment ...
I'll have to see which new supply from China has better quality :-) And I have to re-check the current my 432 pc. RGBW LED living room lamp actually draws ...
Maybe repair it by using a bigger tank cap?
Just pulled apart a laptop charger, it has the same case and many components are the same EG. main cap, rectifier, heatsinks, toroids and the transformers (visually similar). It did have a strange fine grid/mesh pcb soldered and glued underneath, I think it was for RFI absorb and cancel. 240AC - 19V 4A . strangely it made a very faint ticking noise when operating. Used to make a nasty crackle when plugging into mains (no inrush damping). Quality seemed reasonable.
Nice video ! That big heatsink crossing the isolation barrier is kind of worrisome, though.
Yeah, that struck me too. I'm assuming in the original design it was grounded, but now it's not, it's just like a busbar in-the-making between high and low side?
A very through analysis of the flyback supply. Thanks, a great job! A couple of points needed clarification-
- Why is a snubber put across the secondary schottky? Is it because they are underrated?
- There is a choke drawn connected to the drain of the MOSFET; is it needed, and what is its role?
I love the way you are stripping cables.
Btw. It is very disapointing how they cheat on power of this adaptor. I've got 12v6a to power car radio at home and its twice as big.
Your explanation was very complete. I would like to have had you tell us what should and would have been changed to make it the 5A as noted. Thanks for your video.
Trust me ur English is better than mine
I love ur accent. It makes that channel special and the fact that u use russian old tools is even more impressive. Im subing on 3 accounts:)
i havent seeing better explanation then that.... and you pulled a schematic out of it, ....it is insane work. good job. loved the flying resistor :) that was funny..
It is based on 3.5A Power Supply but they rename it to 5A.
Very impressive schematic overviev
Thanks. I learnt about Y capacitors in switch-mode PSUs thanks to this video!
Excellent Explanation Sir....Want individual Component checking and making simple step by step projects on the breadboard with circuit diagram e.g. Schottky Diode, Relay, Output Filter Coil, Mosfet, Transistor, Fet, Optocuplor etc. as per your choice. Then many people with basic electronics knowledge can enhance their knowledge on higher level.
My new favorite electronics channel!
very good practically explained and good way of reverse engineering.
Congratulations to you for good presentation on this difficult subject of SMPS.
This guy has the greatest accent on YouTuuuuube.
Would have been nice to see output current *after* output smoothing choke with measurement of input/output efficiency. FWIW, there was a fuse (size?) wrapped in heat-shrink and space silk-screened on PCB for an in-rush limiter (themistor).
Cliff Matthews That choke won't do much to output ripple, it is there to prevent the output cable spewing garbage into the ether. RF compliance
MrJohhhnnnyyy - OK yeah, you're right (especially since that bulk cap is super-undersized). He really needs someone to buy him an adjustable DC load.. and maybe that new EEVblog multimeter... :-)
Hey lad, no content for two weeks..? What's the hold up... school exams or holidays?
Cliff Matthews Both :) And even more) Had to do stuff quickly, without camera rolling. But I do have some footage for two videos.
Danyk is a beast, he can make the load if he really wants to. He made that 60v 40a supply, I guess he's just lazy to build the load :D
He is Danyk? Wow, that tells me why I keep coming back to this channel. I've had to trim down my channel subscriptions because I'm lazy too.. :-) (It's easier too sit here semi-retired watching video's in my shop and surrounded by >2 million components, than to get up and do something... ha!) I wish I had my youth back :-(
I will keep checking your channel for more inspiration.
Cliff Matthews
...but it's not so bad to sit around and see what others are doing. It's better than whatever commercial garbage is on TV. These guys are my motivation to try to do something useful with my 15-20 minutes at a time on the bench. They always seem to show some little detail I want to see for myself or try to figure out.
Excellent and thorough review.
Cool video! There is also a spark gap between primary and secondary.
Great walkthrough and analysis. I appreciate your humour also
hi sir i saw your video i want to say you are perfect..you are very good teaching...thankyou for make this video
I had another PSU with very similar parts, different brand and model... and this another one is labeled 12V 3.33A. More accurate value !
I like how you perform the tutorials
wow excellent schematic explanation
The output inductor is out but the tow capasitor is in parallel so 2 output caps are in use.
You can activate the video subtitles on your channel. Thank you so much
WOW. Thanks for spending the time to reverse engineer this. I just discovered your channel. You do great work reversing engineering many other things too. I admire your dedication. I appreciate it. Viewed many old vids and subscribed. I will be watching for new vids. Happy New Year.
I like to see those reverse engineered schematics as a jpg or png link. I helps to print and improvise it later. Showing it on the video is limiting.
Just pause the video and take a screen shot.
Thanks, that was a great overview - though I did miss seeing the cat.
For the diode and MOSFET ratings they might be ok as there's a snubber to limit the reverse voltage.
Thank you sir, This explains why the power supply I bought off Amazon for my CPAP machine keeps cycling. The picture was the same as the original and the model number was the same as the original but just a piece of garbage. Now I know
Quality video, I enjoyed the layout of the schematic and how you explained each section, great way to learn.
maybe that strange voltage reference is the reason why it is not blowing up even tough it has lower rating transistor and schottky diode for 12 volt power supply
wow! your so good at this man!! keep it up :D
Thank you for this thorough review
Good explanation. More videos please. I am learning from you.thanks a lot
Your video was so very well put together,very entertaining, thank you👍
Nice post- very thorough, informative, and well presented.
you are one awesome engineer bruh..
All is very good and ultimate, but why you are not showing number of main pwm chip in all power supply.???
Your videos are best thing on the internet
Thanks for your worknand good explanations. Greentings from PL
I've seen a few of these types of power supplies from Asia. I wouldn't turn my back on them or leave them plugged in. The ones like this that are not ultrasonicly welded seem really sketchy to me. I don't have a problem with the phone chargers at 500mA-2,000mA, but that higher current stuff scares me. No parts match in the ones I've taken apart. The caps are like 5 different brands, the IC's look like bad knockoffs, like Texas Instruments with a logo that looks like the Hawaiian islands. Something just doesn't feel right about them. I've talked to several Firemen that work around here and they often say the number one cause of single home housefires around Southern California seems to be switch mode power supplies. Not exactly scientific research, but I think there might be some potential truth. Of course, around here wildfires destroy far far more structures....
I'm all for hacking and mod'ing SMPS, I might even hack one of these in a pinch, but I certainly won't leave it all alone or powered while I'm away from my bench ;)
BTW, I've seen you talk about the TL431 a bit strange a few times. I'm no expert by any stretch, but these configurations are not using the 2.5v reference as a 2.5v reference. They are using the "adjustable" configuration. The formula is quite simple:
Vout=(1+R1/R2)*Vref
I did a couple of videos on how to hack laptop/printer power supplies and a MC34063 buck circuit by swapping "R1 and R2" with a trimmer and a regular pot to change the voltage. I demonstrated the formula and how to calculate it in those videos.
Thanks for explaining the snubber circuit in this video. That was one aspect of these SMPS designs I was still clueless about ;)
-Jake
Против Глобал
I just built an iPhone power adapter for free a couple of days ago. You just need 4 bias resistors to get the data lines at 1.8 and 2.6 volts IIRC... Some of us are too cheap to pay $1
;-)
...but your 100% correct. This stuff exists because of stupid people. It always bugs me when people make prejudice statements about Asian people/countries, China specifically. People tend to forget they don't need us. Their domestic market is much larger than most people realize. If you can figure out how to navigate taobao..., we get the junk they don't want. They have a lot of nice stuff that isn't sold outside of China. We get sold cheap crap because that's all we pay money for. The roles are about to reverse. In the next decade we will be trying to sell to them and translating everything into simplified Chinese while they complain about our ignorance.
From what I have seen with equipment, all of it needs cooling. If someone takes one of these power supplies and covers it with bedding, they should not be surprised by a fire. It is not the fault of the cheap lower supply but the person that lacks respect for electricity and electronics. There is no such thing as a perfect power supply all of them dissipate heat, and if people can't understand that perhaps they should not be using electronics. The only other solution is to put thermal fuses or some other thermal shutdown to protect people from themselves. This means that the power supply will shutdown and no output, and people being like they are will say that there is something wrong with the supply even though it is operating as designed. As a result they do not put the safeties in because they do not want to have to take back on their own cost things that have nothing wrong with them. As a result we get house fires. There needs to be standards used internationally for thermal protection for idiots to protect the rest of us from them and protect the manufactures as well.
Cant wait to See you in the the next videoooo!!!
0:58 what a wire stripping freestyle
thanks so much for your videos I have gained so much
This circuit is repaired from laptop power adapter of 19.2 volt 3 amps power rating
the output caps are all 16v, it's unlikely they have changed them all.
thank you so much the
6 pins package control is (OB2263)
"ground is going nowhere" 😂
Good and helpful for my understanding on the circuit. Very much thankful. Would you give more detailed explanation on the same parallel resistance circuit for power dissipation? Just one resistance seems good for saving space and material cost plus installation work .
The Swedish Chef is also an electronics instructor.
He was more singing than talking to us over the video.... Caapaceettaaaaaarrrrrr
really interesting. Thanks for the clear walk through.
suplaaaaay from chinaaaaa
Master you are.keep going
OMG the rectifying diode of the auxiliary winding is 1N4007, 1A 1KV, which is not a fast diode, so it's going to act very bad! I would expect FR107, which has the same rating but it's a fast diode
The diode in the snubber network is RL207, 2A 1KV, and once again it's not a fast diode, which makes the snubber network useless and so the transistor is very likely to get blown up by the inductive spikes! I would expect FR207, which has the same rating but it's a fast diode!
You should try blowing up the capacitors. Hook them to the mains, in series with a kettle or something to limit maximum power. :D
Thanks for your work! I'm impressed!
I use old tech such as laptop adapters as once upon a time it used to not be manufactured in china, or at least made with quality.
I bought an aftermarket laptop power supply and I noticed it interfered with nearby radios. I guess the reason is due to the lack of ground connection and the output connected before the filter inductor.
I have the same powersupply that claims 12V 6A output, but it could sustain 12V only up to 4A load.
this looks a lot like the one I had die...with a chip inside blown apart decapped and some components (mosfets?) burned thru the board until they desoldered themselves. worked great for a couple weekends running a small electric cooler. mine was rated 10 amp though.