13" MBP - USB power

Discussion in 'MacBook Pro' started by MooneyDriver, Jun 26, 2009.

  1. MooneyDriver macrumors newbie

    Jun 12, 2009
    I have a 13" MBP connected to an HP LP2475W, and the monitor has it's own powered USB bus which I use to connect a wireless keyboard and mouse (and a USB from MBP to HP to drive it). Sometimes - not always - I get a USB device low power warning when I wake up the MBP and the mouse doesn't work. I unplug the USB from the MBP, plug it back in, and it works fine. Occasionally it takes two or three tries before it works.

    Am I missing something here? Does it take a while before the MBP USB power comes to life?
  2. Anuba macrumors 68040


    Feb 9, 2005
    USB seems weird on all Macs really. On both my iMac 24" and my MBP 17" there's a lot of weird stuff going on with USB during boot. USB power flickers on and off like mad several times.

    On my iMac I have this Korg MIDI keyboard with a bunch of backlit LCD displays. I've had it connected to my various PCs for years without glitches. But if that thing is connected when my iMac boots up, it flickers on and off a couple of times and then it goes into this eerie state where the LCD displays start pulsating like strobe lights. I have to plug it in after booting up, and if the iMac goes to sleep while the keyboard is connected, I get a low power warning when I wake the computer up.

    On my MBP I have this Kensington USB hub with various gadgets connected. When it's connected on power up, weird things occur... sometimes the MBP doesn't boot at all, it just sits there with a black screen. Once I got a kernel panic. I couldn't use my Logitech USB speakers with it (they are not USB powered, they run on their own AC, the USB is just for sound) because the display would flicker and a burst of load popping noises are emitted from the speakers for several seconds. So again, I can't plug in USB until the system is fully booted.

    Mac USB = garbage.

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