Junk I Bought: My PSU Just Won’t Do

I have an Acer monitor that I’ve owned for around 15 years, and thanks to my having paid extra at the time for the model sporting a DVI socket for HDMI compatibility it still finds a place as one of my desktop monitors. It has a power brick that supplies it with 1 2V at 4.5 A, and over the years this has developed an annoying whine. Something’s loose in the magnetics, and I really should replace it. So off to AliExpress I went, and dropped in an order for a 12 V, 5 A power brick.

It’s No Heavyweight

A PSU brick, marked as 12V 5A
So far so good…

These units are pretty standard, a box about 130 mm by 60 mm with an IEC socket at one end and a trailing cable at the other for the low voltage. I’ve had enough of them pass through my hands over the years to know what to expect, so I was dismayed to find when I received my PSU that it was suspiciously light. 86 g compared to the around 250 g I’d expect, so I began to smell a rat. Time for a teardown, and a descent into the world of small switch-mode mains power supplies.

Normally it should be easier to break into Fort Knox than to crack open a mains power supply, because for safety they are ultrasonic welded together. The few times I’ve done it have required some Dremel time and a bit of swearing, so when this case turned out to open fairly easily by levering with a screwdriver it was evident this wasn’t a high-quality item. Sure enough my suspicions were confirmed, for there inside was a much smaller board. It’s clear this isn’t a 5 A power supply, so just what have I received?

For A Fake, It Could Be Worse

A small PCB in a large enclosure
… but not so good inside.

On the board were the components I’d expect for a small switch-mode mains PSU. Rectifier, electrolytic capacitor, control chip, opto-isolator, ferrite transformer. It’s a through-hole board, and unlike with some plug-top chargers the designer has given them plenty of space. Flipping it over and there’s a reasonably healthy 6.25 mm of physical isolation between the two sides, with an additional milled slot beneath the opto-isolator. I can’t comment on the quality of the transformer without prising it apart, but maybe it could be a little more chunky.

The board itself could even be reasonable, even if it’s in a flimsy box wired with dubious hair-thin conductors and secured only by a sticky tab. Zooming in on the chip I found a CSC7224, a little 18 W 8-pin DIP. It’s a generic chip that’s available from more than one Chinese manufacturer, and it implements a pretty straightforward switch-mode PSU. It seems to follow the circuit in the data sheet pretty closely except for the mains filter, meaning that it’s probably a working and not scarily unsafe 12 V supply module. If I needed one good for 1.5 A I’d be happy.

So I’ve been taken for a ride by a supplier on the other side of the world, and for your entertainment and edification I’ve turned it into a Hackaday article. Props to AliExpress for this, when I raised a dispute with photo and description of the hardware they did a no-questions refund. What can I take away from this, other than a warning not to play random PSU roulette again? The first thing is that, from the point of view of the manufacturer, it’s too cheap even to be a successful fake product. If I can tell by its weight that it’s fake the minute I pick it up then they’ve failed, so I’m curious as to why they didn’t make it a bit more convincing by putting a bit more weight in it. At least the chip has overcurrent protection built in, so it will simply refuse to serve 5 A rather than burst into flames.

Thus I’ve opened myself up for ridicule in the comments, and evidently I should have shelled out a little bit more. Have any of you ever been ambushed by a fake PSU?

98 thoughts on “Junk I Bought: My PSU Just Won’t Do

          1. Yeah this. So many great, useable items like PSUs get tossed. And our city drop-off centers have gone to great lengths to stop people from taking stuff. Not that that’s completely deterred me. AC cables, USB leads, small PSUs…

    1. I’ve taken to buying 10-packs of popular barrel plugs to rehome power supplies. I have done Asus to Lenovo, Sony to Lenovo, Apple to wrt54g, and Nintendo Wii to Comcast cable router. Dell to HP, Dell to monitor.

      Toshiba 15v to ruggedized laptop. Etc etc.

      I’ve even got a 24v 5A brick I use with my balance charger.

      Get an Xbox 12v 10A-15A power brick, they will easily run a monitor, or any small 12v computer really with the addition of a PicoPSU or similar. I even use them as a EGPU/GPU power supply.

      1. Power supplies for the white Xbox 360 are great for 3D printers, especially the earlier ones that are higher amps. Cut the plug off and there’s 4 wires. Two are for the 12V, the other two the console shorts together when turned on to activate the 12V output. I designed this 3D printable switch box to go onto the 360 power supply cord. https://www.thingiverse.com/thing:1713061

  1. the sad thing about our time is that random PSU roulette might still be the only choice. it’s hard to find a vendor so reputable that you don’t expect a detectable rate of duds and frauds. most of the online vendors (newegg, amazon, walmart) are working hard to put disreputable suppliers in front of the end user, and i can’t imagine best buy et al are immune to it

    1. I get them from digikey / mouser / etc electronics suppliers, yes they cost more, but I don’t have to waste time and worry about the 1.99$ 12 volt 10 amp power adapter that weighs less than the box it came in

    2. My 2007 laptop used to give me a tingle sensation when touching exposed USB ports. In 2011 a fake $15 power brick died so I replaced it with MeanWell GSM series power supply bought at TME. It was more expensive but no more 50 Hz tingle and it just keeps working, even right now.

      1. Meanwell is in my opinion a chinese brand that you can trust. At least if it’s a genuine that is made by “Mean Well Enterprises Co Ltd”. They are also copied :)

    3. RS, Farnell, Mouser, Digi-Key, etc. etc. – aside from rare cases of supply-chain pollution these guys will only ever be selling stuff that is genuine and does what it says.

      For Amazon, only buy stuff that’s actually supplied by Amazon, not some shady 3rd party seller. Amazon are big enough and smart enough not to be purchasing fake or dangerous goods and selling them directly to consumers as that puts them on hook with safety regulators. Same deal with SD cards and USB sticks, if you want a really genuine SanDisk card, buy it from Amazon @ Amazon.

      1. Unfortunately that doesn’t always work as Amazon co-mingles their goods. In other words, amazon dumps all their widgets into one bin and if a 3rd party seller sends in widgets to be stored by amazon, they take the sellers word on whether it’s a genuine widget or not and dumps it into the same bin as their own sourced widgets.

    4. “the sad thing about our time is that random PSU roulette might still be the only choice”

      There’s another choice we have. Learn about how things work and have a look at their internals. Either you (we) find a defect or you (we) don’t. In worst case, you (we) didn’t see a defect or dedign error. But at least you (we) tried finding it, you (we) performed a check – even if was just visually. That way, you (we) can live a life without regrets, at least. We tried our best.

  2. I was just tasked with scrapping a bunch of machines at work and they all have high quality external 12v 5.5a supplies. Pay for shipping and you’re more than welcome to one.

    1. At my previous workplace there were bins of IT rejects, including a well-populated PSU bin (yes please I’ll take a free 10A 20V PSU for a CNC project). One of the many things I miss about working there.

  3. the only time I have received a cheap power supply is when it came with something (like for instance my little CNC3018), first thing I do is cut the cable(s) off it and chuck it in the bin

    1. I would suspect the cables too — even the IEC one, as having not enough copper in them. It would seem that either Chinese manufacturers are “bad at math” (euphemism for stupid), or they don’t (morally) care since there is no serious consequence when “caught”. I had a 2.5A 12V supply die in a few months on a 0.8A max LED load. There must have been too much ripple as the HV filter cap dried out then blew an diode open (no fuse). The USA went through a period like that back in the early 20th century, and there are still some that try to get away with it. Many early Japanese products were lousy. Once there are consequences, they will “straighten up” and do better.

      I bought a 2TB flash drive on Amazon, knowing that it had to be fake at its $15 price. I got it then spent about 4 hours searching the web for an analysis tool (way harder than it should be!), then spent nearly two days on testing (but no standing over it, just in elapsed test time). As best as I can tell, it was really a 250GB drive. Of course, Amazon refunded me, but it was still for sale 3 weeks later. Now, it’s listed as “unavailable” — no warning or “get your refund” notice: https://smile.amazon.com/gp/product/B09KNJCC33

      It’s no different than most of our politics right now — just do or say anything and you will likely get away with it because there is no law that “ACURATELY DESCRIBES THAT SPECIFIC CRIME” on the books. Clearly, morals don’t matter.

      1. I just saw a “2TB” micro SD card on Aliexpress this morning for $4.99. Obviously it’s fake, but it’s got a bunch of glowing “wow this is great” reviews.

        Above, someone commented that the people doing this might be stupid. No, it’s too widespread; they’re trying to rip people off and probably hoping the amounts are too small per person to be worth chargebacks.

        1. One thing I never buy from Aliexpress is SD cards or Flash Drives. Are they telling the truth? Probably not. It’s just not worth the wait. Microcenter sells them a very good price.

          1. I once bought a 32GB Sandisk µSD at Aliexpress for 5$ to 7$. I did some testing (capacity and speed) and could not find a flaw. Obviously I was lucky. :-) But of course nobody can gurantee

          2. Actually if you want some free SD cards or USB drives, buy exactly that, the silly low money item that purports to be 2TB, and then test it, and get your money back. When you determine how much it can actually hold, repartition it for that space,

          3. good one Abjq! ;-)

            I needed some 16 GB SD micro cards for an audio recorder, and the Aliexpress offering for 16 GB was as advertised, after I verified it. Not the fastest cards on the planet, but so far, fast enough for my recorder.

          4. I don’t buy anything from Ali Express. Then I don’t have to waste time testing it and requesting a refund.

            I never toss a PS. I have drawer full and can usually find something that I can make work.

      2. “or they don’t (morally) care since there is no serious consequence when ‘caught’”

        That. Only if their thievery makes national or international news will they be punished. For example, the guy who produced and sold fake baby formula there was executed. Not so for the guy who makes electronic hardware with fake standards approval markings and false specs that burns down your home.

      3. What I want is a software tool that un-does whatever is done to the cards and thumb drives to fake their capacity. Reset them to their correct size and they could be useful. a “2TB” that’s really 250GB? That’s some decent storage, though likely to be slow writing.

  4. You are not being exposed, everybody has bought the wrong part at least once. This was just a reminder / lesson that some things are not to be bought at some places if you expect a determined level of quality.

  5. It made for an interesting writeup with no real surprises. For that sort of thing, I ask nicely at the recycler where I am currently hauling my excess to, and they will almost always let me select one or two out of a box of 50 or so. I tend to select units marked with Dell or some known major brand, and almost always have great luck.

    1. That’s easy. Get a module from Mouser or DigiKey that is small enough to fit and delivers the name plate wattage. Slap in the emptied box and seal it back up.

      1. Sure, but with that attitude you (we) won’t learn anything about electricity, we develop no skills. And a fuse doesn’t install itself magically, either.
        We’ll be mentally inferior to an 8 year old from the 1950s who built his own radio with his/her construction set. Is that really what we wanna become? A customer, a module pusher? Jesus. 🙄

    2. Honestly, with something like that you’re likely going to wind up doing so many modifications that you might as well just build the new supply from scratch. For a 200W-plus off-line adapter your best bet would be an LT8312-based PFC boost ( https://www.analog.com/media/en/technical-documentation/data-sheets/8312fa.pdf ) feeding an LTC3722-based phase-shifted full bridge ( https://www.analog.com/media/en/technical-documentation/data-sheets/LTC3722-1-3722-2.pdf )to provide a 12V power rail you can do all sorts of fun things with.

  6. I just paid Amazon $26 for what they claim is a genuine Dell supply for my laptop. Seems a fair price if true. Should it turn out otherwise, I can always send it back and try again :-)

    1. I hope you got the 230w power supply, that’s about what I pay for the 170w and up ones. Even the 330w I feel bad paying more than 40 for. I sometimes have to search a bit, but there are deals. (FB, Ebay et al. Knowing compatible supplies: Lenovo Legion supplies will run a P50,P70,71 etc mobile workstation for example)

      1. Sure, but with that attitude you won’t learn anything about electricity.
        You’ll be mentally inferior to an 8 year old from the 1950s who built his own radio with his/her construction set. Is that really what you wanna become? A customer, a module pusher? Jeez. 🙄

    1. I buy all kinds of things on AliExpress, and almost always am extremely pleased. Every ESP8266 board I have ever used has come from them, usb to serial adapters, and so forth. Probably a good guideline is that if you are buying circuit boards and stuff intended for the “hacker” market, you will be OK. Things that target the everyday consumer (like the power supply now being discussed), all bets are off. All of the ARM boards I play with (Orange Pi and such) have come from AliExpress and are top quality. The only downside is the 2 to 3 week wait, but generally the savings makes that worth it. Plan ahead and stock up! Buy STM32 boards 10 at a time, etc.

      1. Mechanical components tend to cost about 10x what they’re worth if you don’t have a business relationship with a vendor here in the states. I typically go to aliexpress for nuts, bolts, rod, bearings, linear rail, acme screw, etc. As long as one isn’t expecting to put the same loads through it as a THK or NGK item, they’re generally pretty good, and have yet to disappoint me.

      2. I have used AliExpress for a few years now, and have found that the best way to determine the quality of the product is to check what other products the vendor is offering. Specialized product vendors are usually reliable, in terms of shipping time, and quality of the product, while the vendors that offer anything from power supplies to nail varnish, batteries to “diet” pills, are the ones that will ship to you junk, or the parcel will get “lost” in transit.
        I have bought quite a few OrangePi boards, but all of them from their official Aliexpress store.

      3. I have an Orange Pi Plus 2E. It has an Allwinner H3. The newest Android I can get that’s been built specifically for it is 4.4 – despite there being other SBCs from Orange Pi with the H3 chip, and some TV Boxes, with Android 7 available. I’d be happy with Android 5 so I could use it as an internet TV box for YouTube.

        Since YouTube and some others have altered their stuff specifically to un-support Android older than 5, a lot of older yet still decent hardwear has become much less useful.

    2. For stuff like this, you can generally get it from Amazon and get your money back if it’s not as described (hint: read the most recent reviews). Otherwise, if you use Paypal, you can sometimes buy cheaper from Ebay and you can also get a refund if it’s not as described.

      I’ve also bought from Aliexpress for longer than I can remember, hundreds of transactions, and can count on one hand the times I’ve been disappointed. In most cases, a dispute will get you a refund there as well.

    3. Ditto the aliexpress expriences. I buy connectors, magjacks and small modules. Where possible search for actual part numbers. The aliexpress vendors worry about bad reviews. The one time I had a problem, I threatened a bad review and it was straightened out inside of 24hrs after a week of screwing around.

    4. I save a lot there. Good 100x microscope lens for my camera in a C mount. 17 usd

      De pinning tool for my modular cable making, six to 8 bucks.

      You can’t find these things on Amazin or Eh bay, and if you do it’s usually shipping from the same place for 50%

    5. My last $400 order from US was never delivered (cd’s from dr dobs magazine) and no way to get a refund. Aliexpress always come true on resonable arguments for a refund. SO I guess I’ll keep shopping at Ali.

  7. I Google the specs and try my hardest to find a name brand supply, say dell, and or modify it if I have to, I’ve seen to many power supplies go melty or smokey or straight up damage whatever they are powering to ever risk it these days. My favourite was one my mum bought off Amazon for a monitor, would wipe out her WiFi when powered, the emissions must have been horrific. It also smelled melty.

  8. “”Thus I’ve opened myself up for ridicule in the comments,””

    Yah, what were you thinking, buying an Acer????

    Just kidding, they’ve been pretty solid post about 2005… they had a rough patch before that. If I threw a rock from my seat here, it would have a high chance of hitting something from them.

  9. I go to Goodwill, monitors, power supplies, keyboards….
    I like the split keybaoards, so i have a couple of spares.
    Is it new? No. Does it work? Yes. Keeps it out of the landfill.
    Did it need a cleanup? Yes. Now it looks new, is already breoken
    in without the stiffness of a new keyboard.
    If you have a Goodwill or other secondhand store near you, it’s worth a look.

  10. I have 2 of these. One is a 5A and the other is an 8A. I have not tried to tear them apart, but so far they seem to support their stated rating. I did buy one, different vendor, that was meant to power an HDD. That failed, and the 2nd one doesn’t seem to want to drive my SATA HDD. But mostly I have been satisfied with my Ali purchases. Since most things on AMZ and Ebay are made in China but at 3x the cost, it makes sense to plan purchases from Ali ahead because of shipping time. Though many of ebay and AMZ items are shipped direct from China anyway.

  11. I buy 12V 1A adapters on aliexpress. 50 at a time.

    I put these through their steps recently. They continue to work up to about 1.7A but get too hot and stop while they cool off.

    Then I needed 2A, so I bought a few 2A adapters. Those turned out to be 0.5A and at 0.55A they would start to drop in voltage, about 1V at 1A and “hickup” mode at 1.2A.

    Aliexpress refused to refund. :-( I had to send the devices back, which would cost more than “taking my loss”.

    So I tried a different supplier. This time the dropoff would start around 1.8A, so from then on I tested them around 1.7A. I didn’t record it for the first one, but the second one measured 327mAh. I did get my money back on those. But I still don’t have a working adapter. :-(

    1. Weird. I always get refunds when something is blatantly not as advertised. I ordered some 12v 3a adapters and they gave about .85a. I sent a picture of a multimeter showing the current and was immediately refunded without having to ship them back. I think it all comes down to having a couple pictures showing the exact issue and short text saying what the advertised spec vs actual specs were.

      1. yes. They respect pictures and video. The few times I’ve had problems, some well-chosen photos (confirming a wrong size, or a malfunction) included with the complaint, gave me a refund.

        Jenny, did you actually try the questionable PSU on your monitor?

  12. If you’re thrifting for 12V power supplies in the random PSU bins, here’s a hint: pick up Nintendo Wii AC adapters. 12V at 3.7A works in a lot of situations, and those bricks are un-kaput-able. You need to supply your own plug though.

  13. Since the article did not, it’s worth noting that insurers will deny claims if they catch whiff of using non-rated power supplies (generally UL-Listed or ETL).

    If it’s “new” and sells for less than used power bricks, then well, you probably also buy “16TB SD cards” that ebay and Amazon sell for $9. Buyer beware.

    As someone else said, purchase “real” used power bricks instead.

  14. Guys, girls.. Please don’t buy cheap PSUs! They’re your front line between you and deadly AC!

    Too many teens died in the bathtub because their phone chargers carried a hot pin on the 5v/9v DC side!
    With a proper charger/PSU, they could still be alive!

    Please, please use your brains! Don’t think about cost efficiency when lifes are at stage! Buy/use a quality product.

    Also keep in mind that switching-psus are generally made as cheap as possible, they even have questionable circuits often (which is borderline). If you can, use lab PSUs for certain applications. They have safety mechanisms. Heck, even using old ATX PSUs might be safer than those China bricks. Always show respect to power supplies and AC power.

    1. Or just avoid using ANYTHING plugged into the mains while in the bathtub!!

      Do people still use bathtubs? I thought the whole world had gone to showers these days. All this makes me think of my favorite scene in “ground hog days”.

    2. …really? This happens?

      Our local electrical code dictates that you can’t have an AC outlet or switch within human reach of a tub or shower. And so either the bathroom violates code, or someone has gone to great lengths to be able to use a device connected to a charger, in the tub.

      Just, wow. Tubs are for relaxing and pondering, then jumping out nekkid and running down the street shouting “Eureka!!”.

  15. I highly recommend MegaWatt power supplies. Nice switch-mode units, very clean (clean enough to power my Icom IC-R8600 SDR receiver). One 33 amp MegaWatt is enough to power 2 monitors plus a bunch of other 12vdc computer peripherals.

  16. > for safety they are ultrasonic welded together. The few times I’ve done it have required some Dremel time and a bit of swearing,

    chisel+hammer should help you a lot with ultrasonic welds, and you can easily superglue the case back together!

    1. I have been an amateur radio operator for 22 years. Gone through many a battery in that time. A great trick for breaking open battery packs or anything else ultrasonic welded is to put them in the freezer overnight then whack around the edges with a hammer while still cold. Works like a champ!

  17. I’ve been ambushed by genuine PSU. One little 12V 2A or so Asus EEE power brick, that i measuret to shutdown at 2.5A or something like that. So i used it at 2A to power a grill motor and after an hour of grilling, it disintegrated explosively. I guess these are not rated for continuous duty.

  18. China is the leading importer of Russian Oil. The Chinese and United States have been extremely quiet about this fact. If we buy goods from China, and China buys Russian Oil to make and ship products to the United States, then are we not supporting Putin’s War in Ukraine?

    Its almost impossible to do what we do without buying a Chinese part. But for now I’m trying to hold off on purchasing components from China for any projects. If our trading partners do not have our values then they really make poor partners.

    Imagine if China sent Putin the message that what he is doing was unacceptable. And then stopped paying for Russian Oil. The war would be over much quicker.

    But for the United States to put pressure on China, or for US Consumers to stop buying Chinese Goods, would require sacrifices that we apparently do not even want to talk about.

  19. Nice, thanks for this article. Came here via a Google search as I ordered the exact same style supply from eBay, only it’s a 12v 10a supply. Sure enough I was immediately suspicious by the lack of weight. Inspired by what you’ve done I took it apart – which again was quite easy, only had some stuff retention clips – and immediately I noticed written on the PCB “12V6A”. Not the same board as in your one, but the PCB layout matches all the sizes in the stencil exactly, so I wager that the 6A/8A/10A variants are all identical.

    I think I might keep it as a spare for, maybe, 3A max loads. I wouldn’t trust it with any more! Can be sure I’ll give the eBay seller negative feedback for this one lol.

  20. I actually just bought two of those exact PSUs. I immediately ripped one apart with a butter knife when I felt how light it was, I’ve had packs of gum harder to get into than these mains connected PSUs.

    Overall, the separation of high and low is better than I expected but it’s definitely not going to give 5 amps and it poses exposure to high-voltage if the case cracks open.

    Anyone got a recommendation for a good 12v 5amp supply?

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