Hi, [CCing Greg and linux-usb since people might be interested in this, too] since I was having a VERY AWFUL experience with my external USB burner (whenever I wanted to use it I had tons of problems getting it detected properly, for several years! And no, it wasn't a simple missing USB unusual_devs software issue...), I'd like to get the following entry added to http://www.linux-usb.org/FAQ.html since this is the most central place (isn't it?) where people might search for help: Q: Why is detection of my USB device (e.g. with lsusb) very spotty / unreliable? A: This could be due to electrical grounding issues. If you observe tiny flashes at the connector when plugging the USB connector into your PC case, then you know you've got a winner... Several external USB storage cases (for burners, HDDs) are pretty much isolated from earth and their USB port's ground connection (or entire metal case) develops a potential difference versus your PC's metal case (which usually is properly grounded). If you then plug in the USB cable, there's a sudden discharge of this potential difference (voltage) which may go as far as incapacitating your USB storage device's USB controller, requiring a cold restart of the entire storage device to _try_ to get it detected successfully again (if you're unlucky, then this problem might EVEN KILL your USB device or PC). A countermeasure which helped in my case may be to physically connect the metal case of your USB storage device with the metal case of your PC to avoid the buildup of voltage differences. Alternatively try reversing your PC's power plug in order to reverse live/neutral pins and change their influence on the PC's outer case. ** DISCLAIMER **: Whatever you do, please be aware that you're dealing with potentially very harmful live electricity here and consult an electrical engineer whenever you have any questions! And especially if you suspect that those of your devices which happen to need grounding (e.g. those with a metal housing) have a faulty ground connection (*VERY DANGEROUS*), which might be the very reason for this USB detection failure! [entry submitted by Andreas Mohr] Not sure whether this should better be listed under "Trouble Shooting" or "Specific Hardware Problems", just decide for yourself. Many thanks for providing this vital Linux infrastructure service! Andreas Mohr -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
