Re: [Thinkpad] Questions re: external HD enclosures (USB)

A recently purchased 7K60 external USB drive only starts with both
PCMCIA USB ports AND the PS/2 power plugged.

Once it spins, however, it's quite impressive.

- RWM

Cottrell, Eric wrote:

>Hello,
>
>PCMCIA can not supply the amount of power called for in the Firewire Spec.
>Some Firewire and USB Cardbus Cards have a coaxial power jack so an external
>power source can be used. Again usually a cable to the PS/2 port.
>
>Also a 4-pin Firewire connector does not have power pins.
>
>So we discovered another reason to have a PS/2 port on a laptop.
>
>73 Eric
>
>-----Original Message-----
>From: thinkpad-bounces@stderr.org [mailto:thinkpad-bounces@stderr.org]On
>Behalf Of Andrew Webber
>Sent: Tuesday, December 21, 2004 10:48 PM
>To: thinkpad@stderr.org
>Subject: RE: [Thinkpad] Questions re: external HD enclosures (USB)
>
>
>On Tue, 21 Dec 2004 12:32:53 -0500, Paul A. Pennington wrote:
>
>
>
>>Spend a few bucks more and get a drive with a wall-wart power
>>supply. Hard disks draw too much current to draw it from a
>>notebook computer. Check on CyberGuys:
>>
>> www.cyberguys.com
>>
>>
>
>On Tue, 21 Dec 2004 14:45:19 -0500, Cottrell, Eric wrote:
>
>
>
>>I agree. The USB info I have seen indicates a 500mA power limit
>>through the bus. Anything over that must be self-powered.
>>2.5 Drive specs say around 520mA average(!) when operating and
>>800mA to 1100mA maximum during startup.
>>
>>I suspect some drive enclosure makers get away with bus powered
>>because some USB ports can provide more than 500mA of current.
>>
>>
>
>Okay, thanks to you both. But I do see a lot of enclosures that
>_aren't_ powered. I guess they're just taking a chance. Though
>some do specify the PS2 for power, and some have a USB cable that
>takes up two connections at the PC end (I guess that gives them
>1000mA?).
>
>It's too bad because I like the idea of not hauling around another
>wall-wart that probably weighs more than the drive and almost as
>much as my notebook!
>
>
>
>
>>I have a nice combo USB 2.0/Firewire enclosure. It is only
>>bus-powered on the Firewire side because Firewire is spec'd
>>to provide 60 watts of power. There is a coaxial power jack
>>and a power cable to a PS/2 pass-thru connector is included.
>>If I did not have a PS/2 jack on the computer I would need a
>>5 Volt regulated wall wart to plug into the coaxial power
>>jack when using USB 2.0
>>
>>
>
>This reminds me of my external DVD-RW, it requires power when
>connected by USB and not when connected by Firewire. But I ran
>into a problem with that which I never chased down.
>
>I bought a PCMCIA Firewire card, of course it isn't thick enough
>for a Firewire connector but rather than a dongle it has a Firewire
>cable. The DVD burner doesn't power up when it's connected to
>that. Is it possible the PCMCIA card doesn't provide the requisite
>power? I don't have it handy (put it into a machine with only USB
>1.1) but I do remember card's cable being less thick than the one
>that came with the drive.
>
>If it has to provide power to conform to the Firewire spec, I might
>get it back and see if a (more expensive) Firewire HD enclosure
>would do the trick for me.
>
>Thanks!
>

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Received on Wed Dec 22 10:39:17 2004