On Thu, 5 Jul 2007, Karl Kiniger wrote: > I will be away for about two weeks (fortunately holidays :-) but > will have to continue on that problem when I am back.. I appreciate > your response and I am sure it is a hardware problem. > > There are several hundreds of these machines out in the field and > only a few are showing these kinds of problem - some do it once > per week and others do it several times per day. > > Not all machines hat a total USB breakdown like this one though. > A likely candidate is the USB<>IDE DVD drive, another is > the Sony printer at root hub port 7 - and of course the > whole user interface behind the 4 port hub. > > We already replaced the main board. > > Yesterday evening it happened while I was sitting close to the > machine - unfortunately w/o PS2 keyboard. So I removed first the > user interface and plugged in a Cherry USB kbd which is known to > work - errors -71 and did not work. > > Then user interface plug into another machine - worked fine. > > Unplugged USB<>IDE - still no luck with the external USB kbd. > > When I powered off the Sony Printer at port 7 suddenly the external USB kbd > worked. Powered Sony printer on again - all still worked. > Replugged everything to the original root hub ports - all worked fine. > > When doing the unplugging game two days ago it was the empty > 7 port hub on root hub port 2 which brought life back into the USB. > > Since then the test is running for more than 24 hours w/o any unusual > log display. > > I would really want to know how to design a bad USB device which is > capable to bring the whole USB down - I tried already with > overcurrent etc but this all affected only the one port I played with. > > Additional ideas are highly appreciated.
About the only clue I can give you is this: Somebody once wrote in, saying that attaching an empty cable (i.e., with no device at the far end) to a USB port was enough to cause errors on other ports of the same controller. Probably he was getting reflections off the end of the cable. Someone else wrote recently (within the last month) that he was able to fix the -71 errors by adding extra capacitance between the two USB data lines; the controller's value was not within spec. Good luck, Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Linux-usb-users@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
