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Thread: Powered USB hub 5v feedback

  1. #21
    Constant Bitrate
    Join Date
    Feb 2011
    I had a hub like that. But I noticed it too late when my USB ports werent working anymore and so I disconnected and reconnected the hub again and saw a spark flying. It was already too late, it had destroyed ALL of the USB ports on the mainboard. Even some capacitors were damaged.

  2. #22
    Maximum Bitrate
    Join Date
    May 2005
    For those of you who measured the voltage from the hub on the upstream port, was the voltage present on the 5v power line or the data line?

    Since the hub is powered, I'm wondering if simply disconnecting the 5v line between the PC and the hub would solve the problem. Of course that doesn't help if the voltage somehow leaks to the USB D+ line.

  3. #23
    FLAC Mickz's Avatar
    Join Date
    Sep 2009
    Hi, problem in my case was voltage leaking from 12v powered devices that have USB connections to the PC. This USB interface in these powered devices would Phantom power the +5v USB line to around 2.8 volts, prior to the PC starting (powered on). As the +5V/standby USB line is common to everything in the PC and every internal/external device powered from +5v, including things the SSD. That voltage is enough to part power some devices (especially devices without brownout protection) and cause them to be not ready or locked when the PC boots.

    There is also the problem of some powered Hubs leaking back to the same +5v line and causing the same problem if they are powered before the PSU +5 line is active. They need to come up at the same time as the PSU as there are timing requirements for initialisation of SOME USB devices to consider.
    Last edited by Mickz; 07-06-2012 at 08:08 PM.
    Palm sized ainol MiniPC, 8" Transreflective PRO, Win10, Reverse camera, Dual 10HZ GPS RX's for Speed Display & Sat Nav, FM-DAB & Phone Modules, iDrive interface. T-Screen HVAC control, custom microcontrollers, microcode and FE.

  4. #24
    Maximum Bitrate
    Join Date
    May 2005
    Rochester, NH
    The 5 volts was on the power line, not the data line. I tried cutting the 5 volt line and it worked but had other consequences that I cannot remember at the moment. I thought I explained them in this thread but I'm too lazy to go back and read the thread right now... Sorry.

    Definitely the easiest solution was to get a good quality hub. I purchased one from radio shack and it has been fine for the last several months.

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