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I'm planning to create a media center with Raspberry Pi. For that I would like to attach a 500 GB USB hard disk drive that I already own.

Right now, I'm trying XBian, but I already tried Raspbmc and the same thing happened. I'm using an 8 GB SD card for the OS, a 1.0 A cellphone charger to power the Raspberry Pi, Samsung LCD TV for display (HDMI).

From what I read I need a powered USB hub in order to power the USB hard disk drive, so I bought one. I bought a Soyntec powered hub with seven USB ports (Model Nexoos 395, just for the record).

If I connect the keyboard into one of the Raspberry Pi's USB ports and the hub on the other (without anything plugged into the hub and without powering the hub), everything works well. If I add a 16 GB pendrive in the hub (wihtout powering the hub), the Raspberry Pi recognizes the pendrive and works fine. If I unplug the pendrive from the hub, and I plug the hub's power cord in order to get it powered (without plugging any usb device, just the hub to the Raspberry Pi), everything works well.

The problem comes when I try to plug anything into the hub after is powered. If I plug either the pendrive (which worked in the hub before powering the hub) or the USB hard disk drive, the screen starts to "flicker" (black screen, back to normal for a second, black screen, and so on).

So the problem seems to be if I plug something into the hub when the hub is powered.... because if the hub is not powered, it seems to work. But if I don't power the hub I won't be able to use my hard disk drive which is my objective.

All the uses that I thought for my Raspberry Pi rely on the USB hard disk drive (media player, torrent seedbox, and NAS).

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migrated from stackoverflow.com Oct 21 '12 at 23:14

This question came from our site for professional and enthusiast programmers.

    
Have you checked this elinux.org/Rpi_USB_check-list? Have you tried everything plugged into the USB hub (keyboard included)? I have never heard of this brand of hub, you may want to try one of the verified working hubs from this list elinux.org/RPi_VerifiedPeripherals. –  Steve Robillard Oct 21 '12 at 23:25
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Strange, seems like the USB hub is drawing power from the Pi, despite being self powered. –  Jivings Oct 21 '12 at 23:40

1 Answer 1

It's possible that the USB hub you have is trying to power the Pi through the USB cable feeding into the Pi. This is a common problem with USB hubs and may cause strange problems like you are experiencing. Sounds to me like it only does this when you plug something into the hub.

If you take a look here: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=28&t=8926 you'll see the procedure for fixing a different USB hub. It's called the "cut the red wire" solution and many RPi owners have had to resort to it. It's a simple procedure. Even I managed to not mess it up (and I'm still using the hub 3 months on).

Essentially, some USB hubs don't obey the rules and send power up the USB cable as well as the signal that you want it to send from the peripheral.

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