Google engineer finds USB Type-C cable that’s so bad it fried his Chromebook
arstechnica.co.ukPrevious discussion: https://news.ycombinator.com/item?id=11021665
I'm not an electrical engineer, but wiring something other than ground to the ground pin is...well, I suspect it's straight-up malicious, although why you'd want to do something like this, I don't know.
> I suspect it's straight-up malicious
Hanlon's razor: "never assume malice when stupidity will suffice."
It doesn't even make rational sense for a business creating cables to intentionally damage equipment. They'd just get sued, tons of bad PR/reviews, and gain nothing obvious.
More likely they just had production line issues, lack of QA, and poor training for staff. Resulted in malfunctioning equipment being sold. Most people that build cables don't understand how the cable works, they just follow instructions they're given (e.g. "red cable into position #1, white/black cable into #2, yellow into #3," etc).
Ultimately this might just be one incorrectly assembled cable; but the issue here is that they don't QA cables before they leave the shop. Electrical testing on most cables is quick, inexpensive, and automatable. They likely saved a few cent per cable by skipping it, but in the cable industry that might be significant savings.
My money is on incompetence too, but it certainly could be malicious. For example, imagine a small company run by two frat brother entrepreneur guys. They bribe some factory supervisor in Taiwan for the designs to a product. They cant understand anything about it but they decide to tweak it to make it cheaper. Their greatly underpaid sole engineer discovers his girlfriend is cheating with the main entrepreneur guy. This is pretty disgusting because engineer man is a good guy and main guy has an underage girlfriend living in a plywood loft built inside a storage unit. One day engineer man says "fuck this I'm going to be a fucking farmer now". He modifies the designs to suck before grabbing a check from the middle of the stack in the printer and heads out the door. Six months later the factory in Taiwan wants the designs for the new product. Main guy digs around on the file system and finds the modified stuff. His new engineer just started and isnt really an engineer but rather an engineering student- he says he will "do the needful". Instead of looking over the designs new engineer plays rocket league and smokes weed. Another six months later engineer guy is growing organic carrots and heritage lambs with his new gf who has kind of fucked up feet and not great teeth but she's nice to him and is good at farm chores. At night he goes to read /r/girlsgoodatfarmchores and at some point sees a link to a video of a cable frying the shit out of the thing its plugged into. "Huh, I really ought to clean this shit out from under my fingernails" he thinks.
>This is pretty disgusting because engineer man is a good guy and main guy has an underage girlfriend living in a plywood loft built inside a storage unit. One day engineer man says "fuck this I'm going to be a fucking farmer now".
If engineer man does that, then he is not a good guy.
If engineer man does that, then he is a scummy asshole.
You've mis-parsed the parent. His ...story contains an 'engineering man' and a 'main man.'
Ah, yes, I see that now. Thanks for pointing that out.
Can you make this into a movie script? :)
Given all the other problems with this cable, it seems to be yet another case of an "entrepreneur" trying to make a quick buck, except this one happened to (probably accidentally) add destruction to fraud.
I still wonder, what's in the minds of people who sell this kind of crap, and where did their conscience go? I wish we'd have a reliable way of getting rid of such vendors.
My point is that it may be more complicated to assume stupidity, because the process of getting someone that incredibly dumb into a position where he's dictating the wiring pattern of the cable, with nobody telling him he's an idiot in the process, is far more complex than most forms of stupidity. Hanlon and Occam may be at odds here.
So, there's a couple of interesting bits of context. Firstly, the way these dodgy cables try and suck more juice out of sockets is by putting passives between the data lines to trick the phone into a genuine OEM charger from the same manufacturer, so it ignores the USB power specs.
Secondly, the way USB declares that something is a host is by tying ground to the sheath.
So, there's precedent for tying things together (through a passive), and tying things to ground (but only things that are floating). MY guess is that they bought some connectors designed for USB host that had the sheath tied to ground and in their attempts to tie D+ and D- together shorted to ground. Only a guess though, you really don't want to do this.
Does anyone else find it concerning that our new and best technology is so fragile that even the slightest fezz-up in what should be a passive signal-cable can cause our otherwise state of the art equipment to fry itself?
Is reliability, durability and robustness nowhere to be found in any single spec for our new standards?
It was not a slight fezz-up. It was miswiring in a power cable. It's like electrician wiring the live pin into ground pin and then wondering why one gets electrocuted by so many devices.
No specification can defend against a hostile, or sufficiently incompetent, implementer.
It's what fuses and diodes are used for. You know how when you write a program you never trust user-input? This should be the same thing, but physically. A well-designed USB port wouldn't fry the computer like it did.
There is a limit on how much user malice should be tolerated vs the cost (additional components used, larger devices etc etc) to implement all of that. Especially as someone can always just rip the device open and circumvent all that causing breakage. How many stops there should be versus malicious usage?
USB devices can handle things like the ground and voltage being shorted, as that can happen in normal use through wear and tear. However the flip of ground and voltage lines can only happen if it is done intentionally. As an example either by malicious user or by a factory just randomly mashing wires together and then lying to the customers that they're selling an USB cable.
Or an untrained or too-tired worker puts the assembly in the jig upside-down and pushes the button. ker-chunk. Then the worker throws the cable in the good bin because he gets paid by the kg of cables produced, and fired if the bad bin fills up.
It's 5A, they could install a polyfuse, or they could monitor the current and turn it off with a transistor.
As I already explained in the previous thread about this cable, current limiting is implemented in USB hosts and chargers and it doesn't help in this case. If the powered device sinks more than 5A of reverse current, it already is dead.
For protection from reverse voltage, the powered device needs a circuit which detects negative voltage and disconnects power (which would easily consume few cm² of PCB area) or a very beefy clamping diode to shunt the negative current into ground before it reaches other circuits and pray that charger's current limiter trips before the diode overheats and vaporizes.
And even if you do that, some idiot can still make a cable which applies -5V to some data line instead of the power line, so that your whole unobtanium Intel southbridge chip goes poof. Are you going to multiply the protection circuit by the number of wires in USB3 cable and at the same time make it pass insanely fast signals without distortion?
At some point you have to give up and simply assume that cable vendors are at least minimally competent.
Is that really true? (I have no idea just asking). Is there nothing you could put in the device to prevent bad inputs from damaging the internals? (for some definition of bad)
Is it a question of impossibility? Or cost? Or bulk? or something else?
I thttp://www.fiftythree.org/etherkiller/ttp://www.fiftythree.o... it's a matter of foreseeing the potential failure modes and correctly deciding which ones are so remote as to be not worth the cost and complexity to protect against. For instance, I don't think there's a consumer device out there that wouldn't fry if connected directly to mains AC through any peripheral port at all. But that doesn't stop someone from making a cable that connects AC to USB and saying it's a fast charge cable on Amazon. That's a more extreme case than this, but only because it's more obvious what the flaw in the cable is.
A cable with a mains plug at one end and USB on the other is obviously wrong, though.
Mains power is legitimately difficult to deal with. Power that's five volts out of spec is not.
A cable that puts 5 volts into random pin is also obviously wrong.
It's a balancing act between the probable failure modes and the cost of replacing the broken devices. Hostile manufacturers is not common enough of a failure mode (vs just Amazon sending a replacement device) to accept the additional cost for every single unit made. It makes no sense to spend 1 dollar more per device if it saves 1 cents per device on average for replacement costs.
If this kind of issue becomes more common then it might make sense. But for now it doesn't seem likely.
>A cable that puts 5 volts into random pin is also obviously wrong.
I mean that the physical object is obviously wrong. Such a cable looks like any other cable.
Just as a side note, some of the cheapest USB chargers have 1mm or so of clearance between high voltage and low voltage circuits, which places them one small accident away from the "mains to USB adapter cable" territory.
I know, but that's not a cable. You need more diligence when buying transformers, but a wire with a plug shouldn't be able to do unexpected damage.
Sorry about the weird url problem. I typed this on my phone in the HN app and had tried pasting in a URL at the end of my text. After being seemingly unable to get the URL to show up after two tries I gave up and cut down my post to not talk about the URL. I seem to have somehow inadvertently double pasted said URL to the beginning of my post in the process of all that.
I have actually seen a wall plug with V- and GND mixed up. Luckily nobody was injured and nothing was set on fire, but we did wonder why touching the dishwasher gave us a noticeable shock until we figured out what was wrong.
Assuming you mean neutral and ground, at least those are nominally the same voltage. If you mean something else then I'm going to need more explanation of what wires are in that plug, and I'm slightly terrified that it still ran.
From the review:
> I directly analyzed the Surjtech cable using a Type-C breakout board and a multimeter, and it appears that they completely miswired the cable. The GND pin on the Type-A plug is tied to the Vbus pins on the Type-C plug. The Vbus pin on the Type-A plug is tied to GND on the Type-C plug.
Although I haven't read the spec, following the spec is a key part making use of a standard.
I would say that the Chromebook's USB ports are probably to blame as well. Shorting the +Vpp pin to GND should only result in sinking the maximum current but not in the port being damaged. Likewise, I'd expect the signal port to be protected against shorting it to GND or connecting it to a (moderately) high input voltage. The USB standard does probably not require these kind of protections, but they are nevertheless good, defensive design for any port that gets connected to a large number of unknown and potentially dangerous / badly designed devices.
Btw I already destroyed some parallel, serial and USB ports when connecting them to devices I built that malfunctioned or were ill designed (during prototyping), so as a measure of safety I now often use optocouplers to galvanically isolate my circuit from the port, which can help to prevent most kinds of damage.
This was not shorting +Vpp to GND; this was putting -Vpp in the +Vpp pin. All pins are referenced to GND, which is 0V by definition, so if you put +5V in it, it's the same as subtracting 5V from the voltage in all the other pins. And since they put the 0V in +Vpp, it became -5V. Most devices aren't prepared for negative voltages.
Point taken, but I still think that the device should be protected against supplying it with a "malicious" input voltage, as there are cheap and robust components to do this. The NCP373 for example (http://www.onsemi.com/pub_link/Collateral/NCP373-D.PDF) protects against voltages between -30 to 30 V and is designed exactly with the "faulty USB cable" use case in mind, and the low-volume cost is just 50 cents (large-volume cost is probably much lower). So I think there really is no excuse for letting a faulty 5 $ USB cable destroy your 1000 - 2000 $ device, even if it supplies an input voltage of the wrong polarity.
This isn't the first time stuff like this has happened. I had a Sansa Fuze MP3 player (from SanDisk) a while back. It used the exact same connector as the iPod. The only difference is two of the wires were swapped. One of them being PWR, so if you used an Apple cord, you would fry your player.
I agree that these ports should be robust against abuse, but reversing polarity on a DC power cable is far from a "slight" screwup.
Its not a slight fezz-up really though. They reversed positive and negative on the power connections. That is a very basic mistake and one that often at least blows a fuse, if not worse.
USB C is not a passive signal cable.
Tomay-to/tomay-to.
Yes, USB C can also be used to provide power (which is also a form of signal), but again my point is that a cable like this is largely expected to be a passive component.
That a crap charger can do bad things would probably surprise no one, but hooking a good charger up to a good unit shouldn't be able to fry anything, ever.
Wasn't USB C supposed to make our lives easier? If we need to ensure all our USB C gadgets, cables and chargers are all not-exploding certified, in parts and in combination, I may just go back to plain old regular USB.
Hooking up a good charger up to a good unit with the ground and voltage wires reversed can fry things.
You can try it with your laptop. Cut the cable after the transformer, flip the ground and live wires and start it. It will get fried. Is this the fault of the specification or the person who intentionally flipped the wires?
The manufacturer was the person flipping the wires in this case.
In this case, it's DC over the USB-C cable. Reverse polarity protection is 1) easy and 2) cheap. That's the most striking part to me, and I almost thought the original post was a joke... because it seems insane there wouldn't be reverse polarity detection built-in to the laptop.
According to the engineer who tested the cable:
"Most devices with a well-specified connector will not have any reverse bias protection in them because both it shouldn't be needed and for the technical reasons of power loss and space used.
Reverse protection is usually done with diodes, the canonical "one-way valve" of electronics. Diodes have a voltage drop across them, usually 0.6V for standard and 0.4V for Schottky types. Using one of these to protect one rail means you'll have about 1W lost to heat when charging at 3A. They are also not small for the currents involved with high-speed charging, being about 7x6x2.5mm for the smallest ones I can find that can handle 3A.
Devices don't usually have too much in the lines of over current protection outside of something like a polyfuse because the device will dictate the current used; if everything is okay in the device it'll set the charging rate and it only needs the most basic of protections in the case that something goes grossly wrong with the device. Sources are what really need overcurrent protection as they don't "have a say" in how much current is drawn."
I mean, yeah, it makes sense. You can reasonably expect chargers/cables not to be quite this jacked up, and in turn, you save space in a space-constrained device. It's just a hard pill to swallow thinking that a stray cable could ruin my device like that.
(Power dissipation aside, I did manage to find some smaller Schottky power diodes that could easily handle the current. There's also the possibility of using a MOSFET, which would turn into Rds(on) * Iavg, so something like 0.15W for Rds(on)=50mOhm, which is much more manageable. I'm just a shade tree electronics guy, so I realize there was probably enough data to make a decision to forego said protection.)
A power cable would be a passive component.
I've had several of Apple's little power charging blocks melt and burn on me.
I had a CRT monitor explode when I was a kid.
Just because stuff is getting smaller doesn't mean it's any more or less liable to break. You use electronics, you're taking a risk, and if you use off-brand, non-official components with other brands, well, hell, even if you're using the official brand apparently, you're playing with, well, not fire, but electricity, which is almost a cousin of fire? Heh.
Pretty sure you could make a "plain old regular" usb cable that would do similar. Maybe you should go back to RS-232? You should also beware of just about any usb device you see, as it could be a http://kukuruku.co/hub/diy/usb-killer in disguise
Unfortunately for you, the exact same problem can happen with plain old regular USB; in fact, this cable had only the wires from plain old regular USB. Reversing the wires on a USB 2.0 cable would have the same effect.
Completely, no, but you can certainly safeguard. The One Laptop Per Child machines could take a reverse of positive and negative leads directly from a car battery and still be okay. The idea being that some poor kid somewhere was going to mess that up one day while trying to give it power. (Or rather I should say an EE prof told me this. I have personally not tried to electrocute any poor OLPCs)
The issue isn't the standard, but that compliance is not regulated by the retailer, the wholesaler, the standards body or the government, which is why consumers are trying to effectively regulate it themselves.
https://usbccompliant.com/ is one output of the engineer's work, for anyone curious
I find my micro USB type-B connectors all eventually fail, and I've been combing through Amazon to find a reliable cable manufacturer, any suggestions?
This is actually by design, kind of. Mini USB didn't have this problem with cable connectors because the complexity was in the jack. Unfortunately that meant that when a failure did occur it was on the divide and couldn't easily be fixed. Micro USB improved on that by shifting the complexity to the plug side. So the cable failing eventually is down to a lesser of two evils engineering tradeoff.
Huh. I know it was the rationale behind micro USB that the jacks would be more reliable than before. But I've actually had multiple micro USB sockets fail, while I've never had a problem with a micro USB plug, or old mini USB plugs or sockets.
In particular, my Nexus 7 needed two replacement jacks. I gave up after the second replacement broke. Phone jacks also get a bit loose after a year or two.
Since micro USB (sockets) are supposed to be more stable, I'm wondering if I'm doing something wrong?
Also the stupid things collect lint in my pocket. I almost threw away a phone that couldn't be charged anymore, only to find I can revive it with a toothpick.
Look for cables made by Volutz. I had never heard of the company before I tried them, but their cables are incredibly durable. They're also 24/20 AWG and I've never seen USB cables that thick sold by anyone else.
Anker.
Yup, I've never had a problem with any of my Anker gear. Cables aren't as flimsy as most of the cheaper ones - they seem pretty sturdy - and their other stuff (I have a 5-port wall charger and a power bank) is top notch as well. I usually don't like advertising a brand like that, but they seem to be doing everything right so far and I'd buy it all again.
I like their charging products, but the cables have been failing at the connector...
Which kind of cable? If it's micro USB, they're designed to fail under low amounts of stress (thus sparing the much more difficult to replace port).
Unless handled with kid gloves, Micro USB cables from all manufacturer break easily.
I'm trying to find info about SurjTech with no luck. Does this company even exist?
I've noticed that a lot of "brands" on Amazon, especially for cheap electronics, seem to only exist on Amazon. I assume people are buying things in bulk from Alibaba or similar and sticking their label on it.
Not necessarily. Here’s a fascinating story about one Amazon retailer: http://www.fastcompany.com/3021229/chaim-pikarski-the-amazon...
This is kinda cool. At first I thought 'ugh, bottom feeder, must be cheap knockoff crap', but the more I read about the business the more respect I got for how he runs it. The fast feedback loop, the quick product iteration...he's going to eat more than one big name's margins. Thanks for sharing.
I wonder if he will be able to recover any of his losses from this company? I know he is reviewing these cables, so hes taking a certain amount of risk, but imagine if someone bought this cable for their new device. I would be pretty pissed if I bought a new device and a new USB cord to charge it and poof out goes the magical smoke and my USB didn't work anymore.
He might have a case. It was sold as an USB cable but clearly it is not actually an USB cable. False advertisement if not anything else.
Establishing liability seems easy. Winning a judgment in small claims court ought to be straightforward. Actually collecting on that judgment could be a challenge depending on where the company is located and how they do business.
I agree. That is really what I was wondering. Will he be able to see any money from this.
The company has "surj" in the name, maybe it's truth in advertising after all :)
He may even have a case against Amazon directly, depending on the circumstances of listing.
Honestly, I don't think he'd need a case against Amazon for this. If the original company refuses to pony up and Amazon was made aware, I feel like they'd just do it since it would be good PR to help make it right since what he's doing is a huge service for Amazon's customers.
I think this is a little far to go to try to get a new laptop outside of whatever Google's laptop upgrade/refresh policy is.
I wonder how many of the other products using the exact same marketing copy[1] are the same part.
[1]https://www.google.com/search?q=%22The+combination+of+sturdy...
Surjtech. Aka surge-tech.
It sounds like they were trying to be honest at least.
I thought type-c was supposed to be the end-all compatibility design. You buy any type-c and it works to spec.
What gives?
What gives is that this was not actually a type C cable, but an evil, broken cable mislabeled as a USB-C cable.
Right... but two questions stick their head up and want answers:
First, USB outlets are supposed to have a bit of a fuse. Why was this upfuckage so spectacular?
Second, why do USB type C ports/cables have 24 pins if there are only 4 wires? I can understand having a couple of extra ones for type/orientation detection and a doubling to support reversion, but 24 is a lot.
> Why was this upfuckage so spectacular?
Because it had power wired to ground. This would be incredibly absurd in ANY variety of powered cable.
This is not merely "noncompliant with spec", it's "actively dangerous because it could start a fire and kill somebody".
I see. Of course it would be very difficult to defend against that. Thanks.
I don't know exactly why these ports aren't protected, but as for your second question, why assume there are only four wires, given there are a lot more pins? Wikipedia has a full pinout and wiring list and you can see there's a lot more going on than that:
https://en.wikipedia.org/wiki/USB_Type-C#Connector_pinouts_a...
USB-C is not merely a new connector for the old USB 2.0, but includes a lot more. It is backwards compatible, but goes well beyond that.
Why assume that, indeed. The salesman who sold me my lovely new macbook told me (when I said something skeptical about quick charging via a thin cable).
Feel free to vote me down for believing something a salesman said.
That'll learn ya.
(For the record, I didn't downvote.)
well, usb type C is supposed to have at least 9 wires, if I recall correctly. This is not a valid type C cable, but it was being sold as one, which is part of the outrage. (aside from the "killing devices" bit)
A "USB Type-C to USB 2.0 Type-A cable" has 4 wires (same as any USB 2.0 cable, really; only the plug in one end is different).
The problem is that this was being sold as a "USB Type-C to USB 3.1 Type-A cable", which is supposed to have 10 wires.
(A full USB Type-C cable has some 18 wires, since it wires both sides separately so the alternate modes which use both sides separately can work.)
I'm not sure any spec for a power cable protects against switching V+ with ground.
The issue here is that some of the type-c cables Amazon is selling are not to spec, they are miswired. The warning here it to stick to reputable type-c manufacturers because miswired cables can damage devices.
The spec is fine but they mis-wired the cable in the factory, badly.
Sounds strange. AFAIK USB shouldn't get fried without external power source. So the Chromebook was bad, not the cable? Down votes? Did I misunderstand something? Just comment with reference that I'm wrong and I'm very happy. Why bother building 'USB Killer' if simple paper clip would fry the motherboard?
More details here:
https://www.amazon.com/review/R2XDBFUD9CTN2R/ref=cm_cr_rdp_p...
The source was a "1st party Apple 12W iPad charger"
The external power source was presumably a wall outlet, since he was testing its ability to charge.
Well that is an entirely different story. I thought that the cable was plugged into a phone and his chromebook (Just like parent).
I was concerned that this might be a flaw in the chrome book, not the cable. The USB bus should be fine to use such a cable, charging is another thing.
When you add the external power source, that completely changes the game.
Best i understand, the guy involved works for Google on USB support in their software and hardware.
What got fried was a Chromebook Pixel. A Chromebook designed and sold by Google directly.
He has been using it and various test instruments to check up on A-to-C adapter cables, as they need to have a specific resistor in them to indicate their nature.
He tried to charge a Chromebook Pixel with the cable. At least that is how I read the article...