This PSU killed a Microsoft Surface and a monitor 

It tried to warn him, the instructions on the back were clear. "replace ac adaptor"

"Temperature increase during use". Well, they weren't lying.

I was immediately bothered with seeing something conductive right across the isolation… seems like an accident just begging to happen. The labeling on the outside is a definite red flag. Rather scary device.

Poor design. They took the trouble isolating the high & low sides of the PS on the PCB (including notching under the optoisolator), but then bridged the isolation gap with the heat sink.

My “cheap replacement power supply” story: I was working with an audio testing company and we spent hours trying to figure out where a certain noise spike was coming from in our device. A lot of audio and cellular test equipment was in use, and all of it was controlled by a laptop computer. Out of frustration, I unplugged the laptop power supply and when we reran the test the noise spike was gone. The power supply turned out to be a cheap aftermarket one. We tossed it in the trash and got a genuine one from another computer and had no more troubles.

That heatsink plate totally compromises the separation. What on earth were they thinking?

As a designer involved in designing equipment to meet the requirements of the International Standards marked on the case, it is totally obvious that even if the power supply met those requirements when it was submitted for testing, it certainly doesn't in its current form. Whether or not that is the case, and I doubt that it was ever submitted for testing, it means that ALL the Approval Markings are either invalid or fake or both. The issue of rampant deception, safety issues and poor quality control is not just overly common in Chinese Products, it's typical. Just less so in products supplied with "Branded Products". CAVEAT EMPTOR!

This is exactly why I don't recommend or use cheap chargers for electronics. I'm shocked they didn't use a ton of adhesive or hot glue inside of it like a lot of cheap products I have seen.

As a "retired" EE, I am reminded of the trinity of production. Cheap, fast, good... pick two. This device was obviously had a rushed design to sell at a low price. Like most cheap Chinese crap.

Can we all take the time to appreciate the work this man is doing to educate and entertain us. Man thank you.

Yet another hard learned lesson on not to use cheap clone power supplies with expensive equipment. There is a reason why the genuine replacement power supply costs more.

1:00 No you read that wrong. It's not CALLED "Replace AC adaptor", it's TELLING you to replace the AC adaptor instead of using it! :-D

They did a good job isolating low voltage from mains, then completely violated it with the heat sink/shield. Just simply dropping the PSU might have made the inductor touch heatsink.

"Vibration during transit" is also my guess. That toroid was not secured. I've repaired many Anton Bauer chargers for pro camcorders which had an identical choke. Luckily, when it broke off it didn't short anything- it just stopped working. A little solder and a lot of hot melt glue fixed them.

Pro tip: The Surface Pros work with USB PD supplies of sufficient wattage, and you can buy Type-C to Surface cables off Amazon. I unfortunately bought a couple of these junk Chinesium dealies before I discovered this fact. Both were prone to sparking on the DC side when you plugged them in. Due to poor grounding, they also cause issues where the Type Cover track pad works intermittently. One had really bad coil whine, the other got quite warm even though it was the correct wattage. Unfortunately, the charge ends always go on all Surface supplies due to the design completely lacking any strain relief. The cable is permanently attached to the brick, and Microsoft wants a fortune (seriously, more than even Apple charges) for an official replacement. With the USB route, you just grab a good quality GaN supply (I got an 65w Anker one) and replace the cables as they wear out. Don't bother with any other third party Surface chargers. I'm pretty sure every one on Amazon is garbage, and a ticking time bomb.

Would be great to see the inside of a genuine adapter and a comparison with this one.

We had the exact same problem (with much less injurious outcome as we had e fuses) at my former workplace. The "fix", which was more of a workaround was to put heatshrink around the whole inductor, which worked of course. A virgin board was fine, but stick it in a container and ship it half way around the earth, yeah, that inductor moved. Bit crap really.

unit: _overheats and blows up_ manufacturer: *that's normal*

When I was looking for a new PSU for my Mac laptop the choices were £40 for a third party part or £85 for a genuine apple part. Perusing the reviews of the third party supply, at least three on the first page basically said "Smoked my laptop". The additional £50-ish seemed like a saving against >£1000 for a new laptop. Lower cost isn't always cheaper.

Had a similar one, though this was caused by the genuine power supply capacitors going bad. 12V supply went out of regulation, all the way to 50V, and killed the equipment it was connected to instead. Fixed the PSU temporarily and yes, other side deader than a doornail. Kind of expensive for the hotel though, it was the master unit for their door cards, and a pretty penny to replace, all because they cheaped out on both power supply, and a transient suppressor diode on the input to the machine as well.

Grounding that heatsink was the BIG design fault. Also another thing I notice is there is no MOV or spark gaps in there to deal with any sort of mains spikes. It could be that the unit experienced a spike, and that was enough to punch through the very thin enamelled wire insulation of the choke.

Usually when I take apart power bricks like that from laptops etc. those large metal heatsinks are well wrapped with a couple of layers of that yellow transformer tape to prevent stuff rubbing and shorting on them.

I pat test thousands items a year. It never ceases to amaze me when people have a £1000 phone, yet buy the cheapest nastiest power adaptor, often from amazon.

I'd love to see a look inside said surface and monitor too, see what died and if it's repairable

That needs to be reported to trading standards. It is potentially lethal.

Am I the only one that's disappointed when electronics don't fail fantastically? Exploding faults are ever so much easier to locate. Plus, you get a show for the cost of the damage, which is better than nothing at all. Thanks for the analysis of this POSU! As a side note, I once worked for a small manufacturer who had entered negotiations with a Chinese manufacturer for pre-made power supplies, when he gave the list of required certifications, he was assured that they could print "any sticker you want". Insistence that the power supplies actually had to meet the certifications got nowhere, a different supplier was found.

I have opened up some dodgy power supplies like this. In my case it was just a generic 24V supply, but it had that same design issue of heatsinks which run between primary and secondary, and I had wondered if that was an issue at the time. Turns out yes, yes very much so. One bone-headed design choice defeats all the separation instantly.

Another reason to be skeptical of cheapie power supplies. I've learned a lot from these post-mortem teardowns.

It might have helped if it had has a protective earth - notice it's a two pin connector. Love the diagnosis Clive, not an easy one to work out.

I look after alot of desktop IT, and some of that is Surface Pros. We have had people loose PSU's so we got a load of "Replacement Surface Chargers" from a very well known IT reseller in the UK that sells to the trade. In no time at all staff were complaining they were feeling a buzzing when touching their MS Surface's. I tested one with my Fluke and sure enough i was seeing about 80v AC on the outer case !. So we issued an email to all staff to throw these chargers in the bin. Thus we got some genuine Microsoft ones.

Like others have mentioned: that's a replacement AC adapter... very possibly a very cheap one at that... I did have some Surface devices die on me (or rather my customers) but usually it's the device or battery in it. Not the peripherals. Tablet go BOOM!

That is 'shocking' Why have any separation/isolation on the board when you are going to put two big strips of metal one end to the other?

Mr. Chin Magoo oversaw the final approval and totally missed this flaw. Good detective work by our Clive, whom has been at the top of his game, providing us with his electronic prowess and even managed to include "knock one out" "schmoo" and "bang" all in one episode. Well done!

I love the heat sink paste on the plastic case. Really useful! Dominic Littlewood did a TV article about a young boy found dead in his bedroom after being electrocuted with a cheap power supply. Still eBay continue to sell this shit.

Some power supplies have the inductors sheathed in thick walled heatshrink tubing, although I think it is more to reduce vibrations than to increase electrical insulation it will do both functions and also increase the protection against rubbing.

I do remember laptop transformers 10-15 years back seemed to get very hot and never seemed to last more than a few years, though they all failed safe for me without damaging equipment. There were cheap replacements from ebay around, but they failed too after a bit. They are far better now, so I guess manufacturers have improved things over the years. One thing I also noticed then was that simple electrical supply fittings of laptops seemed quite poorly made in the early days too, power lead plugs, wire connectors and sockets for example.

The thermal paste coupling the heatsink to the plastic shell is odd, I wonder if they were desperate to fix an overheating issue?

I agree with things just getting by, you cant think of everything every time. But, I don't think it takes a electrical engineer to know that when you intentionally isolate one side of the board from the other, you probably shouldn't go laying a big piece of metal over said isolation.

I've had multiple Surface tablets with batteries doing balloon impressions with OEM chargers. Maybe not the most well designed devices.

There's some "good" aspects on it (like the isolation notch under the opto-isolator) which makes me wonder if they might have copied something else and then down-costed all the components to produce a cheap clone. And perhaps one of the replacements was to switch from an expensive and smaller surface mounted coil (not going to touch the heat sink) with a big and cheap wire-wound one. Or dropped the isolation that the original might have had. I'm wondering if they also replaced a (better) metal-case transistor with a plastic case one, *if* the metal case transistor had negative main voltage on the case that might explain why the shield was connected to that, why not just anchor it in a nearby track that has the same potential. Just speculation and without examining the PCB in detail it's impossible to know if that is the case, even with the PCB it may not be possible to be sure if that's how they go there.

Cheapest possible devise to use with your expensive stuff. Coolest thing was a laptop customer brought in that was struck by lightning it was plugged into the dsl modem with a lan cable

Gotta love the thermal coupling to the plastic case with heatsink compound. "Look, we tried!"

I had a customer hand me a dell laptop to fix once, which clearly had a fakey power adapter, they had copied the dell adapter casing almost to a tea but the fakey adapter weighed a fair bit less than a genuine one. Also the fakey would not charge the battery as the genuine Dell adapter had a 3rd wire in the middle pin, presumably for serial comms, so that the laptop knew the size of the adapter connected.

I’ve seen an unusually high number of aftermarket Surface power supplies fail catastrophically; not just one particular design or manufacturer. We ultimately had to send out an advisory to our users banning these supplies. Often in such cases the Surface is irreparably damaged. I’ve examined a few seemingly from different manufacturers and implementations. In most cases tracking and/or arc-over is apparent, but the exact cause has varied. Signs that the heat sinking material itself provided a path thru isolation has been noted but not in all cases. The only common factor I’ve noted is all such failures have been 3rd party reproductions that attempt to mimic the small compact form factor of the OEM power supply. None of the failures have been aftermarket Surface power supplies with a more typical brick implementation. Regardless of how nice the case finish might be (some have been almost indistinguishable from the OEM model down to the texturized surface finish, regardless) the internals have been sloppily assembled. The OEM form factors is rather compact for a given wattage and I suspect many 3rd party manufactures are unable, unaware or uninterested in ensuing the required implementation and tolerances required of the form factor. Given how difficult this design is to open and inspect I just say stay away from them.

There doesn't appear to be much clearance between the top of the output caps and the underside of the heatsink.

Thank you, I've used this video as a reminder to my team as to why we spend the extra to only buy genuine power supplies and batteries.

I’ve heard of big name power adapters being recalled for similar faults. I seem to remember having to swap adapters about 15 years ago.

The fake looking UL stamp and splattering of other marks to try to assert it's safety kind of tells the whole story even without opening it

I felt like I was watching a good detective movie! I've been doing failure analysis on electronics and mechanical systems for a good while, but that one would have had me stumped beyond seeing the arc-strike between the inductor and the heatsink. I probably would have just figured the power transistor had a meltdown and caused the burnt area due to direct short between the mains in. 😳

They should have covered the tops of the output capacitors as well - they're very close to the un-insulated heat-sink too!

I think the chininglish is a good clue to the dangers inside.

"What a terrible design", you have the most entertaining way of putting things.

I have one of these that just died! It didn't fry my Surface Pro 3, but it just stopped charging the thing. Damn. That could have been expensive.

This is why I don't trust cheap/generic power supplies. You need to use the original PSU for ANYTHING, not just what's expensive.

I like these forensic investigations. I refer to these entertaining videos as "Why things went bang" video series. They're like horror movies, because it's so real that some innocent, cheaply manufactured item might hurt, kill or burn your house down. And we just keep blindly accepting them as "normal" without doing anything as consumers to save ourselves.

I've seen this kind of failure result from very close lighting strikes which were strong enough to kill USB contollers in unconnected tablets.

An interesting trail of evidence. Shame it took out the equipment it was connected to.

That was a fascinating tear down. Thanks for the video Clive. =]

You should be thanked more often. So thank you!!

can you open an old 90s laptop power supply? I remember they used to be the size and weight of a literal brick in the early 90s and steadily got smaller and lighter over the years, but particularly in the last 10 years to now where they're maybe only a fifth the size and less than a tenth of the weight.

I don't know if it's practical after all the damage, but it might be an interesting video to reverse engineer that power supply and then show on the schematic what shorted to the inductor and why that made it go bang.

This is why I always go with an oem psu as it’s far less likely to be this way or at least take a cheap one apart to inspect it first if it is my only option.

This is why I never buy aftermarket power supplies, much prefer a used OEM one to one of these aftermarket units for exactly this reason. Of course there's no guaranty this wont happen, but seems much less likely something like that would be missed.

I have a few of these power supplies, all of a smaller power capacity. I have taken some of them apart, and even when they look a little different on the outside, the components are the same layout as in this one. None of mine have ever burned, and the difference is in the smaller one that I have, the heat sink, and the inductor, are both small enough, that they can't touch each other. One thing I do notice is that on mine, there is a glob of that white "shmoo" on the inductor. I don't know if they were trying to keep it insulated from the heat sink, or if it was to keep it from vibrating. Either way, I am glad to know about this fault. I will keep an eye open for this in the future.

I plugged in the extension brick which acts as the psu and adds more ports to my work laptop. It gave my monitor a warning of over voltage. Brand new from microsofts bussiness store.

"That's annoying! That's a terrible design!", said so beautifully!

I really don't understand why these Chinese clone makes go through all of the effort of designing these things and then just get sloppy randomly with the actual manufacturing. I see this all the time with your teardowns. They're so close to making something perfectly serviceable and they just get so sloppy with the components. Before I watched your channel I enjoyed taking things apart just to look at them. Now that I've been subscribed to your channel for a few years I take things apart just to see if I can make tiny modifications to make these devices much more secure without much effort. Thank you, as always.

On older Surface tablets, you can't get replacement OEM power supply anymore and are forced to roll the dice on these knock-offs (which last maybe a year if you're lucky)

Hopefully it took the stupid horrid tablet with it! (Enterprise IT guy who has to manage a fleet of these overpriced things here, if you can’t guess 😂😂)

It was turned into a mini plasma cutter that cut a notch in the aluminum. Besides, it even tells you will need to "Replace AC adapter" right on it. Who knew it would be immediately? 🤷‍♂️

i find that even OEM chargers give zaps and blow up. Samsung, Apple, they all make this trash too. It's just people have a weird bias that the more expensive something is, the more of a HERO they are. What a clowny world.

In my industry we carry out physical qualification tests which includes vibration, specifically for issues like this. As the PSU was apparently CE marked, they should have done the same (but presumably that was fake). My suspicion is that whoever made the heatsink made it slightly oversize or the hole for fixing it to the FET was drilled in slightly the wrong place. For insulation (between the fouling part and the heatsink) they would have to use something like AshLam (essentially a thin, flexible piece of GRP similar to PCB material) as Kapton would eventually wear or creep through.

Killed a Microsoft product? I'm already feeling better because of that!

often *WHY* inductors are usually heatshrinked in these types of switching power supplies.... and I don't think I've seen any conductive reaching across the isolation gap between the high and low power sides like that.

Good PSU! Die micro$oft, die.

Thanx for showing. I also recognize a general design flaw in this unit. They made the gaps in the PCB and seperation of the low and high voltage side useless by putting the heatsinks over the entire length.

component placement is one of the key design technique.

The amount of times I’ve seen heatsinks bridge gaps of circuitboards is terrifying. Specifically name-brand-giant companies. It especially concerns me when the heatsinks on certain devices are naturally live and/or short by design.

Thank you for the up. A relative too kept the cheap psu in a prebuilt medion pc, and fried his new at the time 1050 ti. being on tight budget, it was a deep burn. a expensive surface with a cheap psu is the cakes cherry. getting a good maybe gold psu will actually save you some quid in the long run considering those have better efficiency.

Nightmare scenario! It blew-out all their expensive equipment. The engineer probably never saw the physical product assembled after designing it on the computer, otherwise they would have been concerned with the proximity of that flimsy coil to that heatsink. When you're just looking at it on the computer all you see is "there is room between", and the sense of scale is different.

If I hadn't recently gone through and purged my stock of dead stuff, I could have sent you a dead "official" surface charger. They're poorly designed so the bespoke computer connector end is easily damaged through bending and they fail. The problem is official ones are ~£70 whereas 3rd party ones are more like £25. At least some of the newer devices are moving to USB-C where it's easier to replace the cable.

Hi Clive, the Heat-sink is connected to Bridge Negative to reduce the EMI produced by the Switching Mosfet capacitively coupled to the Heatsink(Ccase,Cinsulation) and preventing the Heatsink to act as an Antenna for that Switching Noise, It's common Practice to reduce EMI. But Clearly the Component Placing is bad.

Good video. One can get tunnel-vision when trying to manage creepage, focusing just on the board, so air-clearance is neglected.

This is a very nice example on why you are better off paying the money and buying genuine power supplies.

Another example of why you never trust anything you care about to one of these no-name PSUs

I'll admit I still use "questionable" supplies from time to time. Supplies that look good, but you still have that nagging doubt. As a workaround, I usually earth the low voltage negative. Treat it as a Class 1 appliance on both sides of the transformer.

I just watched this video with an identical supply powering a Surface pro 4. Its the third supply I'm using, both an original microsoft one and another knockoff one have blown up with a loud smelly pop in the last 12 months (which I've put down to excess heat as these computers draw quite a lot of power). My better half also complained of constant electric shocks using this current one, though it didn't seem to put out more than a mA or two when measured against mains earth. I'll tear mine apart now - if the inductor and heatsink are too close I'll modify mine and report back on here as another bad one. Big thanks again, another awesome video Clive :-)

I love how it literally says "Replace AC adaptor" right on the casing, as if you shouldn't use it anyways

Thank you, that was a great diagnosis. I love it when you do this. We had a similar experience with pinched wires, passed all tests, then after a while, the insulation gives way and creates a ground path. In our case, it just tripped circuit breakers.

I had a similar (cheap replacement) power-adapter for a MacBook once on my bench. They used a shielded cable for the low voltage side. After some use the cable shielding could sneak back into the casing due to bad stress relief of the cable and eventually made contact to the (live) heatsink. The owner of the MacBook got quite an electric shock from the (then live) metal casing of the MacBook. Luckily the owner and the MacBook survived that incidence.

If there's one thing I've learned in life, it's that you can cheap out on many things, but power supplies should never be one of them.

Hi Big Clive, You are a very talented forensic electrical engineer! Here in the United States I'm sure you would have been hired to determine the reason for an electrical fault or fire by our court system. Or maybe you already do forensic electrical work for Great Britain? Your testimony could determine the outcome of a trial! Great videos! Thank you for all you do!

What a terrible design fault. I was once asked to investigate what was causing a particular model of Dell power supply to fail. Several PSUs died within a few weeks time, so it looked like they had some kind of inherent design flaw, and perhaps I could uncover what it was before it took out the ones still standing. The post-mortem showed a blown main MOSFET and surrounding circuitry. The culprit turned out to be an underrated ceramic snubber cap across the MOSFET: it was only good for 1kV whereas at least 2 or 3 kV would be needed. It would eventually short, causing an avalanche of bad things to happen. So if you happen to have a Dell H240AS-00, you may want to upgrade that cap ASAP.

Why have all that isolation on the board and have a piece of metal connected and going straight to the low voltage side. Major design flaw. This is why you spend the money on a genuine supply. On another note a friend of mine bought a 12v 6 amp PSU online for a flat screen TV that the original PSU had failed. The new PSU could not provide the required current to run the TV. He ended up just letting me have the TV and I took the DC power cord from the original supply and wired it to the 12 volt rail of a PSU from an old computer and added a switch to turn on the supply and changed the fan. I have a nice old school flat screen from the 2000s. I use it on my playstation 2 for games and watching movies. Works great.

To answer your question @6:08 of "How many of these are out there...", A LOT. I work in IT, and Surface Pros account for about half the staffs mobile computers. Against our advice, some teams buy these cheap replacements when needed to try and save some money. In the end, they end up having to replace the whole device. Spend the ~$90 on the charger to save ~$1000 on a new device, don't try to save $70 on the charger.

The first thing I thought was like KiloSierraAlpha, that the inductor originally had adequate clearance from the heat sink but got dropped. Dropping it may have pushed the component into the heatsink and from there on it rubbed against the metal until it wore through the coating on the wire. There are multiple millions of economy products out there that perform satisfactorily every day. It's not because the item was a lot cheaper that it was cheap junk. If this company can build a power supply and sell it cheaply imagine how little it costs Microsoft to build theirs. Gouging is a huge problem with big companies. Thank God for the little guys who help keep prices reasonable.

The person who laid out the board put in good clearance between primary and secondary. The person who drew out the metalwork didn't know about all that stuff. Should have had better design review.

I get the impression that the inductor forms part of a buck regulator for the USB socket. It never ceases to amaze me that people will spend hundreds of pounds on a phone or tablet, then buy a cheap and nasty power supply for it. As you've demonstrated many times, Clive, these supplies can destroy your equipment or even kill you. Please keep making these videos, Clive, people need to wake up to these death traps.

I purchased a power supply (built in 3 pin) from ebay for my mum's CCTV , I saw it had the CE mark on it, but my mum said after a week of using it, the unit went bang and the mains tripped, she said the lid had also come off. When I got to see it, the LIVE wire had come loose from the PCB and could touch any part of the circuit board 😞

Nice to see a faulty cheap device being diagnosed, as apposed to cheap electronics being reviewd.