10 Replies Latest reply: Feb 7, 2010 3:06 AM by hype1
ZuMash Level 1 Level 1 (0 points)
when i hook my iphone up to my computer, it starts to charge, then it stops charging, then charges again, then stops charging. basically the thing is vibrating every 5 seconds. and if itunes is open, the phone keeps going from connected to not connected. my iphone has the latest update and im connecting it to windows 7 x86 if that helps
  • ChrisSMcC Level 1 Level 1 (0 points)
    I have the same problem with my phone! I think it maybe my computer because when I connect to my friend's computer it is fine. My computer is a Compaq laptop so I'm wondering if the USB ports aren't performing properly but I checked it in the system and it says its fine. they are USB 2.0 as far as i can tell. Maybe you having the same probablem. are you connecting to a desktop?
  • ChrisSMcC Level 1 Level 1 (0 points)
    I have the same problem with my phone! The problem only showed up just (relatively)recently for me. My computer excepted the i-phone just fine until about a year after I first connected it. I think it maybe my computer because when I connect to my friend's computer it is fine. My computer is a Compaq laptop so I'm wondering if the USB ports aren't performing properly but I checked it in the system and it says its fine. they are USB 2.0 as far as i can tell.

    Maybe you having the same probablem. are you connecting to a desktop?
  • TeXeL Level 1 Level 1 (0 points)
    Take a read at this thread...
    http://discussions.apple.com/thread.jspa?threadID=1799781

    Basically if you disable "USB 2.0 Enhanced Host Controller" in the device manager (if you do not see "USB 2.0" just disable the first "Enhanced Host Controller" in the list) it will not disconnect/reconnect every few seconds anymore. This has worked for me on two computers, however it drastically reduces the transfer rate since we are running at USB 1.1 now.

    Don't forget to turn it back on when you are done so other devices can run at USB 2.0 speeds.

    I have been trying to figure out a way around this but, I'm not getting anywhere. I've updated the USB 2.0 drivers on both machines (Windows XP SP3 and Windows 7) but still no luck.
  • Lawrence Finch Level 7 Level 7 (32,735 points)
    It sounds like a USB problem on your computer. You should only connect the iPhone to a USB port directly on the computer, and not to a hub. Also, if you have ports on the front and back only use the back ports. On most computers ports on the front are an internal hub.

    The reason you need a direct port is the phone needs a minimum of 1/2 amp at 5 volts. If you use a hub the 1/2 amp supplied by the computer feeds all of the ports, so each one may get only 1/8 amp.
  • TeXeL Level 1 Level 1 (0 points)
    Lawrence Finch wrote:
    It sounds like a USB problem on your computer. You should only connect the iPhone to a USB port directly on the computer, and not to a hub. Also, if you have ports on the front and back only use the back ports. On most computers ports on the front are an internal hub.

    The reason you need a direct port is the phone needs a minimum of 1/2 amp at 5 volts. If you use a hub the 1/2 amp supplied by the computer feeds all of the ports, so each one may get only 1/8 amp.


    It's definitely not a USB problem. I have an iPod Touch, Patriot Xporter 16GB USB Stick, and Nikon Camera. All work perfectly via USB 2.0 ports on the back. The iPod will not work on the front ports (for the exact reasons in your second paragraph) however the other two do work on the front ports only at USB 1.1 speed.

    The only issue is the iPhone 3G, it doesn't work with USB 2.0 enabled on two computers. I find it strange that the iPod Touch has no problem. (confused yet? I am lol)
  • Lawrence Finch Level 7 Level 7 (32,735 points)
    TeXeL wrote:
    It's definitely not a USB problem. I have an iPod Touch, Patriot Xporter 16GB USB Stick, and Nikon Camera. All work perfectly via USB 2.0 ports on the back. The iPod will not work on the front ports (for the exact reasons in your second paragraph) however the other two do work on the front ports only at USB 1.1 speed.

    Those aren't all the same thing. The USB stick and the Nikon do not require power from the port; the iPhone does. But, as you point out, the Touch does also. So it may be a problem with your phone. Does it charge using the wall charger? If it does it is most likely a computer problem; if not it is a phone problem.

    There's still a difference between the Touch and the iPhone: The iPhone when plugged in requires more power than the Touch, because it has a cellular subsystem that uses external power when plugged in. The Touch only requires power to charge the battery. So a Touch can work with lower current than the iPhone can.
  • TeXeL Level 1 Level 1 (0 points)
    iPhone charges fine using wall charger and via USB 1.1 on my two PCs. Charges fine at work via USB 2.0.

    Where I'm lost is the fact that its clearly not an iPhone issue because it works on some other PCs and MACs just fine via USB 2.0. With that said it leans toward an issue with the USB on these two PCs I have, yet all other powered USB 2.0 devices including an iPod Touch works fine.

    I've googled this issue and found many other PC users having the exact same problem. Results show USB 2.0 being disabled is the only current work around.
  • Lawrence Finch Level 7 Level 7 (32,735 points)
    Have you tried having the iPhone as the only power-using USB device connected? Also, make sure your USB drivers are the latest version on those 2 computers.
  • TeXeL Level 1 Level 1 (0 points)
    Lawrence Finch wrote:
    Have you tried having the iPhone as the only power-using USB device connected? Also, make sure your USB drivers are the latest version on those 2 computers.


    Yes to both - removed all USB devices, even went to the extent of connecting an old PS2 keyboard and mouse.

    The only thing I haven't tried is another iPhone connected to the same PC, but I don't have access to this option.

    Thanks for the suggestions by the way. I really appreciate it.
  • hype1 Level 1 Level 1 (0 points)
    I am experiencing the same problem. I am working on a MacBook Pro with the latest MACOSX 10.6.2 (Snow Leopard). It doesn't happen to me all the time and it started only lately. I have tried to connect only the iPhone (3GS) to my MacBook to no avail. After I restarted my iPhone it woukdn't keep disconnecting any more. So maybe it is a problem in the iPhone? Try restart your iPhone once in a while.