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Old Dec 7, 2012, 03:56 AM   #1
digitalfailure
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Power via USB

Hi guys

I've ordered a Samsung bluray drive to partner with the 27", just been reading the online specs for the drive as it hasn't arrived yet and the cable is one that uses 2 USB ports to supply enough power to the drive.

My question is, would it still be necessary to use both on the newer iMac with its USB 3 ?
As I understand it, USB 2 supplied 500mA but USB can supply 900mA

Can anyone with the Samsung 506 bluray drive comment?
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Old Dec 7, 2012, 04:25 AM   #2
kaelell
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I was wondering the exact same thing.
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Old Dec 7, 2012, 04:33 AM   #3
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Quote:
Originally Posted by digitalfailure View Post
Hi guys

I've ordered a Samsung bluray drive to partner with the 27", just been reading the online specs for the drive as it hasn't arrived yet and the cable is one that uses 2 USB ports to supply enough power to the drive.

My question is, would it still be necessary to use both on the newer iMac with its USB 3 ?
As I understand it, USB 2 supplied 500mA but USB can supply 900mA

Can anyone with the Samsung 506 bluray drive comment?
I don't have the drive but I have something similar.

I have a USB 2.5" Toshiba with a Y cable so it needs two USB slots, won't mount if on 1 port and even if I plug it into a 2 Amp USB hub it won't mount.

Hope yours does though.
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Old Dec 7, 2012, 04:44 AM   #4
digitalfailure
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I hope so to

My iMac isn't due to arrive until 1st week of January, so there's a while before I'll find out.
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Old Dec 7, 2012, 05:01 AM   #5
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Quote:
Originally Posted by digitalfailure View Post
Hi guys

I've ordered a Samsung bluray drive to partner with the 27", just been reading the online specs for the drive as it hasn't arrived yet and the cable is one that uses 2 USB ports to supply enough power to the drive.

My question is, would it still be necessary to use both on the newer iMac with its USB 3 ?
As I understand it, USB 2 supplied 500mA but USB can supply 900mA

Can anyone with the Samsung 506 bluray drive comment?
Hi,

Macs tend to be on the generous side when it comes to USB power. For a long time, iPods, iPhones and iPads have needed more than the usual amount of USB power to charge whilst being usable. My MacBook Pro has no trouble charging our iPad 2 which I believe draws 1000mA when charging and my MBP's a 2010-vintage.

I've used many 2.5" USB-powered external hard drives without needing USB splitters or external AC adapters. I think I've used one of those Dell DVD drives with a mini-USB connector without any problem.
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Old Dec 7, 2012, 05:07 AM   #6
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I have a hard and fast rule when it comes to drawing power directly from my Macs. I don't. I have a powered hub that I use for the handful of devices that are not self powered...Despite what manuals etc. tell you, taking power from the USB port on any computer places an unnecessary strain on the machines PSU.

I always purchase devices that have their own dedicated PSU, or that can be used via the powered hub. Just my 10c worth.
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Old Dec 7, 2012, 05:19 AM   #7
digitalfailure
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Well the drive has just been delivered days ahead of the estimated date. and the specs indicate a current draw of 1.4A so it's going to need the 2 connect plugs.

I might invest in a powered USB hub at some point and have that in a discrete location away from the mac to cut clutter.

What sort of current output does your hub have available at each port, would it run a cf card reader and charge an iPad 3 at the same time?
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Old Dec 7, 2012, 05:23 AM   #8
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True, you don't want to be pulling more current than the port's rated for - I've seen work PCs' USB ports fail for that very reason. But there's no harm as long as you stay within the rated maximum.

Plus, you're at the mercy of how good the computer manufacturer's DC design is. Our el-cheapo Dells at work seem more than happy to allow you to nuke their USB circuitry. I've seen my Mac cut power to the ports if too much load is connected - I had a badly behaved optical drive cause that.

Edit: yeah, 1.4A will need multiple connectors - but that's explicitly supported by Apple - see this tech note http://support.apple.com/kb/HT4049
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Old Dec 7, 2012, 05:28 AM   #9
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Originally Posted by digitalfailure View Post
Well the drive has just been delivered days ahead of the estimated date. and the specs indicate a current draw of 1.4A so it's going to need the 2 connect plugs.

I might invest in a powered USB hub at some point and have that in a discrete location away from the mac to cut clutter.

What sort of current output does your hub have available at each port, would it run a cf card reader and charge an iPad 3 at the same time?
Powered USB with high Amp output are expensive, *you could also buy a cheap *5 Volt power brick, less expensive.

* If your external has an extra power in plug and if it is 5 Volts, could be different.
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Old Dec 7, 2012, 07:07 AM   #10
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Edit: yeah, 1.4A will need multiple connectors - but that's explicitly supported by Apple - see this tech note http://support.apple.com/kb/HT4049

Very interesting, but knowing apple they probably only enable additional power for their apple devices :P
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Old Dec 7, 2012, 11:00 AM   #11
digitalfailure
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An interesting article for sure, I'm guessing this drive will be ok as it caries the MAC logo on the packaging. Can't see a manufacturer like Samsung adding random logos and claims unless tested and authorised.
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Old Dec 7, 2012, 03:32 PM   #12
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I'm not entirely sure of what your question is, but this is the Blu-ray drive I'm eyeing - http://www.lacie.com/uk/products/product.htm?id=10602

It's USB 3.0, bus powered, and while it doesn't say on that page, it should be compatible with a Mac but may have limited capabilities.

Haven't bought it yet though.

Quote:
Originally Posted by digitalfailure View Post
I might invest in a powered USB hub at some point and have that in a discrete location away from the mac to cut clutter.
Also, I really recommend this for a discrete USB hub - http://www.belkin.com/IWCatProductPa...duct_Id=428714

Not USB 3.0, quite expensive, but damn it's pretty neat.
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