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Google Engineer Warns Against Perils of Buying Cheap, Third-Party USB-C Cables (hothardware.com)

Posted by timothy on from the cables-for-nerds dept.

MojoKid writes: A USB-C cable is just a cable. Or is it? Google engineer Benson Leung noted today that it's definitely not the case. Leung and his teammates at Google work inside of the Chromebook ecosystem, and as such, they've had lots of hands-on experience with USB-C cables. The Chromebook Pixel remains one of the very few notebooks on the market that directly supports USB-C. Nonetheless, in his experience, not all cables are built alike, and in some cases, cheap out-of-spec cables could potentially cause damage to your device. It's such a big problem, in fact, that Leung began buying cables off of Amazon and leaving his feedback on each one. Ultimately, what the problem boils down to is that some of the specifications in a cable may be not well controlled. He notes that in some bad cables, resistor values are incorrect, throwing off power specs wildly — 3A vs 2A in one example.

14 of 206 comments (clear)

  1. Just like HDMI cables by known_coward_69 · · Score: 5, Funny

    which is why i only buy Gold plated, oxygen free, twisted pair, sheathed Monster cables for $99.99 each. I can see the difference

    1. Re:Just like HDMI cables by Anonymous Coward · · Score: 4, Funny

      There is too much Ether in the cheap cables.

    2. Re:Just like HDMI cables by avandesande · · Score: 4, Interesting

      Having a cable format dependent on a resistor in the cable sounds like a poor design to me.
      ++ since it could damage hardware.

      --
      love is just extroverted narcissism
    3. Re:Just like HDMI cables by Aaden42 · · Score: 4, Informative

      Using sense resistors in cables or charger plugs is pretty much universal and works very well. That's how phones tell the difference with between a "standard" 500mA USB port and a 2A high power charger. If the phone tried to draw 2A off a 500mA supply, odds are all the magic blue smoke would get out... (See http://blog.curioussystem.com/...)

      There's nothing wrong with sense resistors when the cables are manufactured properly. The problem is if the manufacturer puts the wrong resistors in because they don't know any better or because they're cheap and they're trying to cheat with cheaper components. In the case of USB 2 stuff, pulling 2A from a 500mA brick probably wouldn't end too well. For USB-C, if you try to pull 3A+ over a wire that's only rated for 500mAh... Well... Most likely what you've got there is a 3 meter long fuse... If you're lucky, the power supply will fail safely before the heat from the additional current ignites anything.

      Or more realistically, you may find the laptop gets flaky when it adjusts its power management to assume it can draw a particular amount of power from the cord only to fall short when power demands reach peak levels.

    4. Re:Just like HDMI cables by kaiser423 · · Score: 5, Informative

      USB type A to type C cables require a different pull-up resistor than the Type C to type C cables. Lots of vendors didn't do their due diligence and just put the USB-C spec'd pull up resistors in their A to C cables. As a result, devices try to draw too much power.

      I bought one of the bad cables, and was wondering why my wall charger was flaking out. Went online, and saw the issue -- my phone was trying to pull too much juice, overloading the charger and putting it into brownout mode. Now, this is a 4-port wall charger, so my other 3 connected devices were sitting there going charging/not charging/not charging at sub 1 second intervals for the ten minutes that it took me to figure it out. After that, my charger was acting really finicky, and I didn't trust it anymore after that current overload so I junked it. So, yea. Not overblown. Actual problem.

    5. Re: Just like HDMI cables by Trongy · · Score: 4, Insightful

      How do you handle backwards compatibility with devices or chargers that can't follow the new communications protocol?

      Perhaps you think you are smarter than the engineers that designed USB-C and USB 3.1, but I do not.

  2. Watch out for Bad Connectors Too by bill_mcgonigle · · Score: 4, Informative

    I bought a few packs of USB-C male and female connectors from China (to use for a non-USB application) and they were really junk. Looked like USB-C but the tolerances were terrible. Too soon for competitive quality forces to have kicked in, I suppose, but they didn't just make these bad connectors to annoy me - they must be out there in the wild too.

    --
    My God, it's Full of Source!
    OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
  3. Re:The legendary Chinese contempt for tolerances by gnupun · · Score: 4, Interesting

    Like health inspectors checking restaurants for bad food or procedures, isn't there an independent company that can randomly test and certify USB cables?

  4. Re:Have to agree, same as HDMI1/2/3 by Anonymous Coward · · Score: 5, Insightful

    The problem is that the average Joe has no way to judge true quality at the time of purchase. It seems the best he can do is perhaps not buy the absolute cheapest. But what about one step up in price from that? Is that "good enough", or still junk? This is a basic flaw in capitalism: for it to work "best", the consumer must know what he is buying. In a world with unknowable and constantly changing suppliers for components, what was a "good" quality product one year could easily become "junk" next year.

    Known "quality" brands that cost more would seem to be the answer to this problem, but they face pressure to lower costs in order to increase profits, so this doesn't seem to be a permanent answer either...

    In the face of this, people just buy cheap, since they can't judge quality, hope it doesn't break, and when it does, just buy another cheap one. Explained in this link: https://en.wikipedia.org/wiki/The_Market_for_Lemons

  5. Benson is a pretty fantastic engineer by tlambert · · Score: 4, Informative

    Benson is a pretty fantastic engineer. He dots the i's and crosses the t's, which is somewhat rare these days.

    I hope Puneet (if Puneet is still his manager, as he was Benson's and mine, when I worked with Benson) is having Google pay for the cables he's buying, instead of Benson paying for them out of pocket.

    In any case, definitely take his Amazon reviews to heart: he knows what the hell he is doing, and he knows which end is the probe and which end goes in the meter. If he says a cable sucks, it sucks, and if he says it's good, it's good.

  6. usb 3 similar problems by divenpuke · · Score: 5, Interesting

    I worked on the first usb 3.0's for Apple. Same problem. We ended up buying nearly every different cable we could find and doing a tolerance study. Things varied so widely that the mouse i was using on my workstation was out of spec! The standards are CRAP. INTENTIONALLY. The mechanical tolerance standards read: for example the height of the internal spring contacts like 3mm max. no...minimum? pretty sure this thing ain't gonna work if the contacts don't...you know...touch anything. I had an internew w/ some asshat at Tyco - (they also make connectors) When i mentioned that the USB standards are crap, he said "oh yeah. we do that too. intentionally. We spend a lot of time developing the connectors to work properly and then because we HAVE to open source the standard, we'll obfuscate things such that we can gain a competitive advantage. Our cables and connectors work out of the box, or other companies are going to have to spend a couple months figuring things out w/ reliability testing before they can release a quality package. I about walked out of the interview at that point. Who signs their name to something that is intentionally a POS?? Speaking w/ the EE's at Apple, the signal integrity was written just as bad as the mechanical. Components of the signal integrity that would be controlled separately by the receptacle were lumped in with the cable. Just all junk. According to one guy Intel outsourced the design of the standard to india/china and just accepted the crap they gave them (because intel doesn't have like ... any mechanical engineers working there) J

  7. Re:Why are resistors needed in a cable? by JediJorgie · · Score: 4, Informative

    yea, the problem is that they are not just cables, they are adapters. They adapt from USB-A to USB-C. As an adapter, they need the proper resister to tell the USB-C connected device how much power they can draw.

  8. Re:Resistors in a cable? by flink · · Score: 4, Insightful

    Gods no. The important thing is that the cable be capable of carrying the current the device requests. If the resistors were just in the device, then it would have no idea if the cable you've used to connect it to the hub is thick enough to carry the current it is about to draw.

  9. Here's his list by godel_56 · · Score: 5, Informative

    Here's the list of cables that he tested, from the TFA. There are ten of them

    http://amzn.to/1MlG3g3