Ac powered usb hub connection?

vbimport

#1

I’ve got an old laptop with usb 1.1 capability.
I added a 2-port usb 2.0 pcmcia card,
which works fine for flash drives and my
mp3 player, but now i need to add
an AC powered hub to run a dvd burner
(asus sdrw-08d1s-u). xp recognizes it
sometimes, usually w/o a disc inserted.
i figure the old laptop just can’t power it.

does it matter if i connect the hub to one of the 2.0
ports on the pcmcia card or to one of the
1.1 ports on the laptop? would their be
a speed or reliability difference?

thanks.


#2

Your just going to have to try them both out and settle with whichever works best. If you purchased a DVD burner with a power brick it would have eliminated the problem, but drawing power from the USB line is going to limit you.

If they sold a power supply that could be plugged into the USB line to help supply power that would work, but it would be risky if it wasn’t a quality unit. It wouldn’t be hard to put something together but I’m not going to risk sending you down that path. If disks don’t burn well at 8x then just try 4x. Check the quality of the disk with an error scanning tool like, Nero CD DVD speed (free if you search for it).


#3

Hi,[QUOTE=ellentk;2525714]I’ve got an old laptop with usb 1.1 capability.
I added a 2-port usb 2.0 pcmcia card,
which works fine for flash drives and my
mp3 player, but now i need to add
an AC powered hub to run a dvd burner
(asus sdrw-08d1s-u). xp recognizes it
sometimes, usually w/o a disc inserted.
i figure the old laptop just can’t power it.[/quote]I guess, this drive did not come with a power supply. Correct me, if I am wrong.
Bus powered optical drives do not comply with USB specifications.
By specification, an USB port provides 500mA @5V on device request.
Slim DVD writers have a power rating of 1500mA @5V. Connecting such a thing to an USB port causes heavy overload which in a worst case scenario can damage the USB port irreversibly.

Edit:
This Asus drive is even more evil. I found a photo of this unit. The sticker on the back mentions a rating of 2000mA @5V :eek:

With Cardbus USB adapters, there is an additional difficulty:
These often are not able to supply the 500mA without additional power feed. That’s why these cards normally have a power terminal, that can be fed either via a PS2 port, an USB port or an external power supply.
But still then, the adapter must not necessarily be able to handle a 200% overload.

does it matter if i connect the hub to one of the 2.0
ports on the pcmcia card or to one of the
1.1 ports on the laptop? would their be
a speed or reliability difference?

An USB hub can be some kind of workaround, but still, nobody can tell you if it can deal with non-compliant devices. If you want to try that, connect it to your USB 2.0 adapter. USB 1.1 is not fast enough to feed a DVD writer properly.

The best option is to return the external slim drive and get one that comes with a sufficient power supply.
External DVD writers without power supply are designed to be sold, and not designed to work.

Michael


#4

Hi Eric and Michael,

Thank you both for your replies. I hadn’t realized the asus drew so much power. Kind of amazing my ancient laptop recognized it even intermittently w/o ac power.

I’ve had the burner for about a year, so I can’t return it. I figured I’d try an AC powered hub, which I can return. I got a Macally mHub (4-port usb 2.0), plugged the hub into one of the the pcmcia 2.0 usb ports and plugged the asus’s two connectors into the hub. Windows recognized the hub and the burner and the burner worked perfectly. I burned 7 discs with no coasters.

Thank you again for all the information.

Ellen


#5

To add stability make sure all power savings on all usb internal hubs are off. You can do this via the hardware properties of your operating system.