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This unofficial PSU exploded and took out an expensive tablet and the monitor it was connected to.
It could have been worse. The fault could have delivered a significant and sustained electric shock from any exposed metal on the tablet.
If you have an identical style of power supply, then I recommend binning it and buying the real thing. At the very least check for the same issue, although that will involve breaking it open.
This unit has the model number DHM1800 and no serial number or traceability. Other names and numbers may be used, so go by the shape and origin.
Don't use cheap power supplies with expensive equipment. At the very least it may impair it's operation.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
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#ElectronicsCreators

It is a pre-exploded device and pre-opened. It has been explored, it's very inside and here's the story so chris sent this and he said as a power supply for a microsoft surface that blew up quite spectacularly moments after being attached to the computer. It destroyed the surface. Beyond repair and the external monitor attached to it, excellent we like to do a good job here.

So let's uh get this out. What voltage is anyway? It puts out 15 volts at 2.58 amps and 5 volts at 1.5 amp. It's got the usb port for the 5 volts and it's got the cable coming out here, which will cut off, don't need that it's just going to stop it being easy to open right here. That is possible.

A lot of the current went down that cable, because that's what blew up the the tablet and the monitor. So now, let's get this out of here. It's also worth mentioning uh. It's called replace, ac adapter, not replacement.

It's all done in chinglish, um model number dhm, 1800 input 100 to 240 volts um warning. It is normal that has certain temperature increasing during use. It's all it's it's a cheap clone right. Let's get down close to this and knock one out.

What do we see? This is a been explored um. One of the problems when they blow up is because it's just a mess. You can see. Tracks have been vaporized here, but you don't know what initiated the problem, because sometimes the fault itself obliterates that problem.

One of the things that comes to mind if a fault occurred in this side, if say, for instance, it just decided to go bang as they sometimes do, there's a possibility. There was flashover from this side, and i do see at the opto isolator, where it's going from the high voltage side to the low voltage side and these pins here in that isolation, slot do suggest an opt isolator under there. That suggests that it could have actually flashed over onto those pins um. Oh sticky, shmoo.

Oh, this gets heatsink compound going on to the plastic case, um anything obvious here. The tracks around the transistor are intact. I would have expected them if that had gone. I would expect them to blow first, but this has been something significant here, but having said that, uh, when a fault occurs like this and the attract vaporizes, even if it's a small one, it creates a metal plasma, a metal loaded, conductive plasma.

That then causes basically a sort of like an arc lamp. It just initiates continuous current flow through that and it engulfs, and that's what makes it go bang with a really big flash. What other routes could have gone? It could have gone via the transformer. The transformer is a common failure mode, let's tilt this back, can i tilt it back, not really um.

There's the output diode another possibility here. Oh that's a plastic case. Diode though another possibility is that you know these metal. Heatsink fins can actually come in contact with something else.

It almost looks like there's a bit of splatter there, but i don't see any skid mark. There is a little bit of skidmark on the bottom here, but i don't think it's near any of the the low voltage components the transistor in here is also plastic. So, oh i'd, look at the way the heat sink comes down to low voltage, but is it clear? Oh look at this. Look at this: let's, let's zoom down in that, in fact i'll bring it up to here and we'll focus on it and uh.

We can actually zoom in a bit further at that. Do you see what i see here? It's actually a little skid mark right next to the inductor, but that transistor is plastic. Is there anything else connected to this um hold on i'll zoom out again and i'll? Go back down to here, which is the best place to be for working. Oh there's a little metal tab.

Just in here, can you see that the little metal tab just uh, anchoring this heatsink down? Oh and it's connected to this track, which is possibly this track that initiated this failure. What would that have been that is going over to there? That is probably class y capacitor over there? So this is probably the negative connection to the power supply. So this little inductor here, let's bend it over and see if it's actually all city, let's just get this thing out completely and see if we can actually see uh, is this going to really help things much yeah? If you look very close at that i'll bring it back up again i'll bring it up to about here, focus on it. Zoom down and you'll see the little telltale splatter of copper there, where it's rubbed through on that aluminum heatsink, and that's where the fault current is taken to the circuitry.

That's annoying what a terrible design they must have known. Something like that could happen unless it was designed for a different inductor. How many of these are out there, because that pretty much means if this was touching when the surface was plugged in or anything was plugged into this usb port? It potentially became live at mains voltage and what connection is that that is going over to the usb um and when that became live? It means voltage. Let's see, where's the tracks for this when it became live at mains voltage.

If you were holding the tablet at a time, you might have noticed a stronger tingle than normal from a charging tablet, because, technically speaking, if this was touching, the tablet would have been live. But when it was plugged into the video monitor, then that provided the path to ground and that's why it's blown up the video monitor as well, because the rectified current has flown through this metro, heatsink onto that inductor and then along. It must have found its way along the low voltage signal, the 15 volts of line to the tablet and then found that, because the tablet's not grounded if it would have just been live on its own, but because it was plugged into the monitor. The current has continued along the signal wires, which is blowing up all the circuitry in the process, and then it's gone to ground via the monitor and that's just killed the monitor as well.

How annoying what a terrible thing! One oversight, if this is because they needed a big heat, sink to try in a plastic enclosure to try and dissipate the heat from this transistor behind here. Can i get that off, i kind of want it off. I want to see a bit more. Let's see if i can unscrew that screw, i can unscrew that screw, but it's not going to help me get the oh there.

It is. Oh, it has. Oh, it's left it's taking quite a divot out of that. That would bring quite a flash, not as much of a flash has happened another bit so i'm guessing the transformer has been absolutely fine.

It's just that pure placement of the components with the low voltage side being next to the high voltage side. And again it's only that case that heatsink could not. You know it could have just been put onto an isolated pad here, but they've actually connected that heatsink onto what appears to be the ground for. What's left of that, circuitry odd, i'm just uh, i'm just pondering things here.

Here's the capacitor this capacitor yet is the negative it's the negative of that big fat capacitor there that's uh connected to that, so that is uh. What initiated the fault that bridge on the from the input side to the output side. That has then caused this to actually blow up, but also in the process. It's the past enough current to actually blow up the equipment.

It was connected to what a shame. It shows that you know sometimes you're better actually getting uh. I mean it looks a relatively good design, but they've just it's got flaws that would have been picked up in high voltage testing. Perhaps, unless it's vibration during transit, maybe they did test it and the vibration that, by rubbing against the aluminum during the transit, is basically just worn away through it.

The fix here might be if they wanted. A quick fix would be to just stick a little piece of insulating material down onto that inductor, which is a filter component to actually block it from making contact with that aluminium. That would have been the cheapest fix, or just take a section of that aluminum out. So the inductor is nowhere near it yeah just this is what happens sometimes, when you design things that you don't really consider odd things that could happen you, maybe they just were thinking in their head.

You know it's grounded, so it's absolutely fine. It's connected to the mains negative and they just didn't really consider the vicinity of those components just perhaps because they were clear on the circuit board and they didn't really think of the aluminium aspect. But that was interesting. It was well worth taking apart.

It's just one of many uh situations where a tree power supply has caused issues and blown something up, but it's also worth mentioning that some prominent high quality branded equipment has also been caught out with the same sort of things where the person designed the aluminium fins. Maybe they increased the size just because there was a issue with overheating and they just filled all the space, but they didn't think about the component that was actually going to be in the circuit board. So it happens to good companies as well as uh as cheapy companies, but there we go interesting well worth exploring.

12 thoughts on “This psu killed a microsoft surface and a monitor”
  1. Avataaar/Circle Created with python_avatars Leroy says:

    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

  2. Avataaar/Circle Created with python_avatars Benny says:

    The inductor should have had clearance to the heat sink. They saved 0.02 dollars on the extra work on the aluminium and caused $1000's of dollars to just one customer…and they are unaccountable…can you see the flaw in the system?

  3. Avataaar/Circle Created with python_avatars D Hristov says:

    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.

  4. Avataaar/Circle Created with python_avatars Clive Mattinson says:

    Hi Big Clive! …… Little Clive here! ๐Ÿ‘๐Ÿ˜‚

    I'll have to buy a "Replace AC Adapter" for my Lenovo Tablet (on which I'm writing this), and hopefully it'll blow โšก๐Ÿ’ฅ๐Ÿ”ฅ it up! ……. Never buy a Lenovo Tablet! It's the WORST Tablet I've ever used! …… Making the mistake of buying a Lenovo has been a bitter pill / Tablet to swallow! ๐Ÿ˜‚๐Ÿ˜‚๐Ÿ˜‚

  5. Avataaar/Circle Created with python_avatars Janus Kobain says:

    Aluminium, or steel, or whatever they used as a thermal interface to the box, better be father from the high-power inductor, I reckon. So cutting part of it would let this PSU serve a better job indeed.

  6. Avataaar/Circle Created with python_avatars Santa Clause says:

    A cheap chinesium replacement charger for a surface, the destruction is well deserved! you should have got an official power supply. "It is normal that has certain temperature increasing during use"……. should have been the one and only clue this person needed. no sympathy what-so-ever.

  7. Avataaar/Circle Created with python_avatars D Hristov says:

    as usual some people just want to see the world burn. Can't just make a decent psu that doesn't kill people or property, and the corporations can't stop fucking wagies with planned obsolescence and single-responsibility work models.

  8. Avataaar/Circle Created with python_avatars William Alten says:

    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.

  9. Avataaar/Circle Created with python_avatars KiloSierraAlpha says:

    Most likely scenario: owner dropped the PSU and since the inductor was heavy and was not glued, it hit the heatsink and caused the short. The bump could have occurred before or during being plugged in.

  10. Avataaar/Circle Created with python_avatars MB says:

    Surfaces need at least 3.5A rated PSUs, and more if you're powering high power USB peripherals (or running the screen at 100% brightness). You really need a powered USB hub for connecting peripherals to a surface.

  11. Avataaar/Circle Created with python_avatars David Reader says:

    It looks like the heatsink is actually marked on the top silk screen, so they did know how close it was to that inductor. I'd clocked very early on that it seemed to carry mains side across to the secondary but was distracted by the soot being in a different area. I do wonder quite what happened to do that after a short to the output.

  12. Avataaar/Circle Created with python_avatars pomonabill220 says:

    GREEEAAAT! I have a Surface with the "original" power supply, but knowing how Microsoft can cheapen things out, I just might open up my power supply and see if it suffers from the same design flaw.
    I think they put the heatsink at -HV is for shielding and HF noise suppression. There wouldn't be any other reason to have the heatsink at such a high voltage.
    Just a poor design.

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