Quoting Bj�rn Stenberg <[EMAIL PROTECTED]>: > Dmitri wrote: > > > I would *very much* doubt that the HDD can be fed with USB power. Most > > HDDs are really power-hungry, and they want dual (+5V, +12V) power > > supplies. > > Actually 2.5" harddisks don't use +12V, only +5V. It seems most drives > need more than the maximum 2.5W when spinning up but less when in use. So, > theoretically, you could solve the power-up surge with a really big > capacitor or something, but you'd still be pushing the limit.
Indeed I remember playing with 2.5" HDD couple of years ago, it had a small adapter and just IDE connector on the other side... but the FAQ from the Chinese site mentioned +12V, and I focused on that. Maybe it is not relevant to the drive being used. > Since disk power loss is a rather unpleasant experience, I personally > would not trust a unit that tries to live off the USB power. This gives me the idea why the older laptop CRASHED upon plugging the device in. I think, it overloaded the bus, and the root hub generated the appropriate event (overload). But it is a rare event, and probably was not debugged well in earlier revisions of the OS. That's why it could crash. Even worse, if that older laptop wasn't equipped with the required USB power switch (something like Micrel MIC2025) then the power on the whole section of the motherboard could be compromised, which could *easily* halt the CPU. The newer driver / new laptop didn't crash, but since the overload on port is pretty much hopeless anyway, that could explain why no device connect was produced - because there was no power! This can be tested with just a voltmeter. Another reason to suspect bad power is that some [small] notebooks have root hub ports that are only capable of 100 mA, not 500 mA as they should be. If so, the solution is simple - use the self-powered hub, or just cut the +5V line and connect it (drive side, of course!) to the external, good +5V power supply. Thanks, Dmitri -- Codito, ergo sum - "I code, therefore I am"
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