Why Are USB-C Cables Frying Laptops?

Why Are USB-C Cables Frying Laptops?

On 2 February 2016, Google engineer Benson Leung reported having his laptop destroyed because of a USB Type-C cable. The ensuing media crisis prompted by this report has had people asking themselves whether using USB-C cables is necessarily safe on their own devices. The cable was designed to help pave the way for future devices that would require very versatile signalling and power transfers. But when such a cable is destroying laptops, perhaps it’s time to start looking at what could possibly cause this and suggest remedies at least for the time being.

Why Are People Moving Towards USB-C?

To understand the problem, we have to understand what USB-C is a solution for. The standard USB cable comes with one head that connects to the host (the fat end) and one that connects to the client. Its communication happens only in one direction, and its design specification allows it to be plugged in only in one particular way. USB-C undoes all of this by using a design specification that lets either end of it be plugged into any of the devices being connected. The “tongue” of the connector is also designed in such a way that it can be connected without hassle.

USB-C’s specification makes it capable of delivering large amounts of power and transferring a significant amount of data (10 gbits/s). This makes it versatile enough to become the only cable you need in your arsenal. Even HDMI isn’t necessary when you have the amount of bandwidth that USB-C can push (which is more than enough for 4K video).

Why Is It Frying Laptops?

usbclaptops-fried

USB-C itself isn’t causing problems with hardware. The specification allows it to be plugged into devices that don’t have USB-C ports by using an adapter. The problem comes when you attempt to use a faulty cable. Benson Leung tried to charge his laptop with a USB-C cable using a charger designed for USB Type-A cables. The charger wants to deliver two amps of current while the laptop is trying to draw three. This leads to a disparity that could end up catastrophically ruining the circuit board (and this was one of those cases). Faulty cables have been ruining our hardware since either has ever existed. This is one of those problems that happens when you try to adapt a new technology with an older one.

How to Prevent This Problem

usbclaptops-head

If you want to avoid getting a faulty cable and minimize the risk of adaptation issues, I suggest you do the following:

  • Look for USB-IF certification. This organization makes an extraordinary effort to test USB cables to ensure that they comply with their specifications fully.
  • Get a cable from a brand you trust. If you bought your equipment from Apple, get your cables from them, too! You could also get a cable from another top manufacturer such as Belkin, Mediabridge, or StarTech.

As long as you’re in the market, don’t forget to make sure that the adapter you’re using isn’t shifty, either.

Do you have any other advice? What should consumers do to ensure that they won’t end up compromising their machines with faulty USB-C cables? Tell us more in a comment!

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9 comments

  1. “The charger wants to deliver two amps of current while the laptop is trying to draw three. This leads to a disparity that could end up catastrophically ruining the circuit board …”

    You have no idea what you’re talking about, do you? How about learning the basics of electricity before you write an article about it? And it looks like it was a voltage problem combined with lack of safeguards on the laptop itself (go Google!), not an amperage issue. [Old Woman Mode] What are they teaching in schools these days? [/Old Woman Mode]

    1. I will try to make this simple:

      Voltage * Amperage = Wattage. USB standards use 5 volts of power (with the exception of USB-PD). The voltage is constant, but the amperage differs between standards. USB 2.0, for example, uses 0.5 amps of current while USB BC 1.2 uses 1.5, and USB-C uses 3. This provides various levels of wattage.

      When a laptop attempts to draw more amperage than the line is able to feed it with, it gets an underpowered signal. That shouldn’t break anything if the safeguards would protect the circuitry. The safeguard in USB-C (as noted in its standard) depends almost entirely on the cable’s own signalling. The laptop is simply the interpreter of the signal. If it receives a “go ahead” from a faulty cable, it will “take the cable’s word for it”.

      1. That still doesn’t make sence.
        If the power supply can only delive 2A*5V = 10 W how can that fry a laptop when the laptop tries to get 3*5=15 W?

        The other way around where the power supply can deliver more then the laptop needs and nothing is resticted you can blow out anything of the laptop.
        The laptop you display has obviuosly been overheated an not just a bit. must have been a hell of a power supply

        Next to this I don’t understand that someone wants to try to CHARGE the laptop with USB wher you have a matching power supply with correct input and connector acompanying the laptop.

        Like trying to hammer in a nail in a wall with a bisquit

  2. KS Augustin’s comment is right on the money…I could hardly believe my eyes when I read that sentence in the article. But it’s hardly the *only* problem with the article.

    – The article states “The standard USB cable comes with one head that connects to the host (the fat end) and one that connects to the client”. Incorrect. The fat end of the cable connects to the device (the “client”) that is being connected to a computer (the “host”); the thin end connects to the computer.

    – Also in describing a standard USB cable, the article states “Its communication happens only in one direction …”. Again, incorrect. USB cables are bi-directional. If they weren’t, external USB drives would be pretty much useless, since you’d only be able to copy data *to* them…you wouldn’t be able to retrieve data *from* them. As well, USB printers wouldn’t be able to send info about ink/toner levels or error conditions back to the computer they’re connected to.

    – The article states “The charger wants to deliver two amps of current while the laptop is trying to draw three”. This would not destroy the laptop. Worst, and most likely, scenario is that the laptop would simply refuse to charge, since it wouldn’t be getting the current it needed. Best scenario is that it *would* charge, but take longer than usual to get to a full charge. But no way would it fry the laptop.

    – The articles states “USB-C’s specification makes it capable of … transferring a significant amount of data (10 gbits/s)”. Firstly, the industry standard nomenclature is “10 gbps”. Secondly, that value isn’t an indication of the *amount* of data that USB-C can transfer, but the *speed* at which it can transfer it. Non-USB-C cables are just as capable of transferring significant amounts of data as USB-C cables are…they just do it slower.

    MTE articles are usually pretty good, but this one misses the mark pretty good. At least it got one thing right…it implies that a faulty cable can cause a world of misery, and that’s undoubtedly the case with this guy’s laptop.

  3. Ooops. Well, just to prove that everyone can make mistakes, I made one. In the last point of my previous comment, I said the industry standard nomenclature is “10 gbps”. That’s wrong…it should have been, of course, “10 Gbps”. As with punctuation, capitalization is everything :-)

  4. “The problem comes when you attempt to use a faulty cable. ”
    Could you please clarify what exactly do you mean by “faulty cable”?
    Do you mean “defective” cable? Or do you mean “improperly used” cable, as in using a cable rated at a lower amperage instead of one rated at a higher amperage? In common usage “faulty” means “defective.” However, in the article you seem to mean “improperly used.”

    1. No, by faulty I meant defective.

      1. Clarify “Defective”

        What’s acutlay wrong with the cable.
        If one wire has gone broken it will just not work.

  5. I just read an article by Bob Rankin, on Feb. 9th, about this USB-C cable issue. I have “copied” what his research has found. Bob was warning his readers, to be very cautious when purchasing a USB-C cable. You need to buy one that is Certified, brands like Belkin or Mediabridge or StarTech.

    This is what I have copied from Bob Rankin’s – Ask Bob Rankin© and it might answer some of the comments.

    “But transition comes with a lot of chaos, as cable makers scramble to grab USB-C market share and buyers are still uncertain what a “good” USB-C cable looks like. Some cable makers have flooded the market with cheap USB-C cables that cut corners dangerously, resulting in instant death for the laptops and other devices into which they are plugged.
    USB-C Cable: ZAP!

    It happened to Google engineer Benson Leung while he was testing USB-C cables. He plugged a cheap cable into his Chromebook Pixel and ZAP! The USB test equipment and the ports on Leung’s Chromebook were instantly and permanently destroyed by a power overload.
    The same thing happened to Dieter Bohn’s Macbook Air. The reviewer for The Verge bought a few inexpensive USB-C cables on Amazon and used one to charge his Nexus 6 phone using the Macbook Air’s power; the cable drew too much power from the laptop. Apple’s excellent surge protection shut down the Macbook Air’s USB ports instantly, but even after rebooting Bohn says the ports now work only “intermittently.”

    Leung reports in his Amazon review of the cable, “it appears that they (Surjtech) 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. “This is a total recipe for disaster and I have 3 pieces of electronics dead to show for it, my Pixel 2015, and two USB PD analyzers.” Bob Rankin © Ask Bob Rankin

    Now, that last paragraph made complete sense to me – It is a major wiring issue that is being done wrong. :)

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