12V 50A 600W power supply - failure analysis & transformer autopsy 

Absolutely true

I couldn't say it any better! Thumbs up for DGW!

Spot on ..........

Absolutely agree!

Absolutely 💯 right 👍. My well wishes to Gentleman 💗

No. That's just the inrush of the capacitors.

@@SAHILKHAN-lu8oq oh

maybe there is other component damage, not only the one you replace

If you connect a load does the supply stay at 7 volts or does it drop further? If it stays at 7 then I'd guess a problem with the feedback circuit. There's probably two resistors and a TL431 on the secondary driving an optocoupler.

yes

yes please

Yaaap

Yes

PLEASE

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Thank you. Would be nice to inspect the fuse and see how many amps it takes to blow it up. Its probably a fake fuse too.

I think, they used some pice of the primary winding - solid aluminium is best for 25A ! :O)

That's possible - i've encountered similar situations in high-end power supplies. These fuses are just slower than good circuit breaker.

@@michamaecki8104 The 600W power supply tripped a 25A 230V circuit breaker (5750W) and it took a few seconds. 🤔

@@Conservator. Yes, because fault initially didn't blew up transistor, that shorted mains. First transformer failed, and after 5s transistor and diode. Also, circuit breakers have solenoid that trips breaker at huge current surge much faster than ordinary fuse, so it's common to see power supplies with blown transistors and fuse intact. Also, to trip standard "B" circuit breaker in 5s, ti would need to see something around 75A.

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thats a great tip you shared there. thank you Bogdan : )

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i have being dreaming with that day since i born

Hell yeah!

He did

@@krisd1000 Yes, I watched the video moments after he released it.

😃😃and my on 18th...

Tak že, dopredu všetko najlepšie majstre. 😀

Mine in may 5 2007.

How do you know 🤔

@@Purple431 mine may 13 2005

or given it a realistic rating

Passable design probably copied from other vendor's product.

Which is the ongoing problem with Chinese products

@@jms019 I'm sure this was a 25-30A power supply they stuck a "50A" label on

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CCA wire is now so common in Chinese products that getting something without it is very rare now. They make it thinner and thinner, I suspect we will soon see all wire coming out from there in products being CCA wire soon, from power cables to the magnetics, with the only copper being PCB traces. The plugs and sockets they supply are getting thinner and thinner, with the metal content being reduced every year, and soon they will probably be going to copper or nickel plated steel for contacts in all products.

@@SeanBZA I had noticed mains power cables using coated aluminium but if the use is light at 240 volts it won't make a massive difference. It looks like we will all have to hoard real mains cables, ok i do anyway lol. I bet you have a few hanging around from previous computers and such.

@@SeanBZA Tehnics uses CCAW on speakers for at least 20yrs

I wouldn't say it would have been fine with the same diameter copper wire. The copper coating actually helps more than you may think because in a HF transformer the skin effect causes most of the current to run in the outer layer anyway, so not as much current wants to flow inside the aluminium anyway. So it depends on the thickness of the copper coating and of course the frequency how much better pure copper would be.

So this is only the seller to blame! The power supply itself is indeed totally okay, especially for the price. Good you told that.

@@robson6285 yes!

You can get one from Mean Well for about double the price. I'd prefer that.

it would be bloody expensive! From Ebay it is already about $50, which is not cheap...

@@Zebra_Paw it is simply the best to buy the cheapest while choosing the type with this valuable knowledge in mind, of course!

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interesting! maybe some capacitor or diode has been expire thats why its get hotter

Idol

@@JayPeeEV andito ka din pla hehe

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In a forward, energy goes directly from the primary side through the transformer into the secondary side. In a flyback, energy from the primary goes into the "transformer" (not really a transformer, rather a coupled inductor pair), gets stored in the air gap, and then released later into the secondary. I'm not sure on the advantages of this topology, but DGW explains the workings very well in his flyback videos, USB charger videos for example.

@@l_szabi Well I was watch in some videos about it (including diodes gone wild) so I know a bidt of theory (like flyback transformer is Inductor that stores energy) but I wonder what's difference "from transformer perspective" between taking energy by snober network and taking that energy into capacitor (especially that in some snober network there is capacitor that take that energy, just to dissipate it in resistor instead of reusing) like, from transformer point of view in both cases energy is pushed in and taken back so what's difference.

rewinding by hand is no fun and also it's not very likely to work at the same current (50A) even with copper wire. see 'skin effect'. The thing still needs proper temperature and over current protection.

I'm afraid that's too complex. You need to wind up your own transformer. (and make it safe! )

If you need to ask for a DIY version of electronics connected to mains, stay away. You can shock anyone using the thing. Buy one: it's less than 20e for a decent one.

​@@stanimir4197 Exactly.

google "aka kasyan english" channel

@@stanimir4197 I can buy but the diy version will be more precised one that's the thing

>decent power supply no thermal protection, no viable over current protection either (unknown voltage ripple - 4 caps on the secondary, tiny coil - for reference meanwell 12V/15A has 6 rubycon caps on the secondary). It's trash bin material - running even 30A w/o over temperature protection is just dumb

@@stanimir4197 I obviously would never use it unattended. I never said its good, its not good at all, but its decent for a very low price. Its usable and cheap (I hope)

@@Chuckiele My point is that likely it has horrid voltage ripple - it was a massive disservice just to use it with incandescent bulbs and heater. They run on just rectified DC (no caps) or even AC. 600W and no power factor correction is another design flaw. Whatever I might connect to 12V /many amps will cost so much more than the power supply, no point to save money on power supply. It should be the most robust part of a system - a failure could burn anything connected to.

I think that the transistors and diodes would fail again if I left it on a bit longer... The overcurrent protection has a certain delay and with a very little impedance in the primary, the current rises very steeply when the transistors turn on. And the diodes have no heatsink, so they tend to overheat before the transistors do.

@@DiodeGoneWild Typically the OCP circuit has a RC circuit on the input, to handle switching on transients that might cause premature switch off, so the current at turn on can rise fairly high, probably well past the SOA ratings of the transistors and diodes, with the shorted transformer. The overcurrent protection is there to normally handlke shorted output, where it will be transformed to a rising current in the primary, and also as cycle termination in normal operation, so it only has to be really operating near the end of the conduction cycle. Shorted primary the current rises very fast, and the turn off only occurs after the RC delay, so current is going to be limited only by ESR of the capacitors and the on state resistance of the MOSFETS, the dodgy capacitors here might ironically have enabled it to survive, as ERS would have been in the tens of ohms, limiting current pulses, though the output voltage would certainly not have been 12V at full load, dropping to whatever the capacitors allowed, with a very high mains ripple component as well. Diodes might not have failed, but the capacitors would definitely have gone boom and given a confetti shower.

The SMPS controller only need a small voltage and current and DGW suspected the primary side of the transformer to be shorted and didn't want to fry again the chopper transistor and the diode again and therefore used a current limitation bulb

@@emmanuelvallee5386 lol tu es là toi !! excellent