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135 Posts

01-19-2013

Austria

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Re: TPT2 has USB port power issue

2013-02-15, 9:08 AM

I think the problem lies in the fact that specs might leave room for interpretation, as I stated in post #166.

 

While manufacturers are expected to interpret them right, there is still room for misinterpretation.

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23 Posts

01-16-2013

Australia

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Re: TPT2 has USB port power issue

2013-02-15, 10:38 AM
@PaulJ333
Just because YOU haven't experienced that, does not mean your assumption is correct.

Motorised peripheral manufacturers DO make devices that exceed the power that can be EXPECTED from one port, which is why they supply a Y-cable.

The thing is that until tablets (of the non-Apple variety) came along, most laptops had more than one USB port and so it was not an issue.

And yes, my external HDDs do NOT work from one port in my 4 year old PVR, but fortunately it has two ports.

And I think it was ScruffR that found that his device failed to work a little below the 500mA mark. But then I don't know if his ammeter was fast enough to capture the attempted startup surge.
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23 Posts

01-16-2013

Australia

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Re: TPT2 has USB port power issue

2013-02-15, 10:40 AM
@moul
?I suspect that the Lenovo ODD might meet the one port spec.
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23 Posts

01-16-2013

Australia

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Re: TPT2 has USB port power issue

2013-02-15, 10:43 AM
@andyk5
They may not have tried an external HDD because they knew they all exceeded a standard port's power.

Remember that Lenovo never promised to POWER such a device from the port, but could just work with them, which assumes they must be powered from somewhere else.
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135 Posts

01-19-2013

Austria

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Re: TPT2 has USB port power issue

2013-02-15, 15:13 PM

wrote:
And I think it was ScruffR that found that his device failed to work a little below the 500mA mark. But then I don't know if his ammeter was fast enough to capture the attempted startup surge.

Yes, it was me, but I have not used an ampere meter, but - as stated in #133 - I used an oscillograph, which definetly is quick enough. And I have even by-passed the startup surge, by temporarily connecting the Y-cable to auxilary power, and then after startup remove that source, to see if the TPT2 could sustain the running HDD - but it failed.

 

And my HDD worked on ONE port despite the fact it came with a Y-cable. So the mere presence of a Y-cable is no proof, that the devices needs more than 500mA, but that there might be "underpowered" ports, allowing to borrow extra power from a "(as)sister port". If there is no "(as)sister port" the single port has to provide 500mA!

 

And on the TPT2 there would be a "sister port" if the charger would not only accept power, but also could provide current - or even a proprietory adaptor for the dock connector would be "acceptable".

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4682 Posts

12-22-2008

Canada

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Re: TPT2 has USB port power issue

2013-02-15, 15:50 PM

ScruffR wrote:

 

And on the TPT2 there would be a "sister port" if the charger would not only accept power, but also could provide current - or even a proprietory adaptor for the dock connector would be "acceptable".


The AC adapter that comes with the TPT2 can both recharge the TPT2 and power an external USB device like an HDD. (Admittedly that would increase recharge time based on the amount of 5VDC current that's diverted to the USB device.)

 

So rather than require the dock, perhaps a special cable to replace the supplied one would sufficient to do the job. This cable would have a male USB at one end that goes into the AC adapter. The other end would have two heads, (1) micro-USB to go to the TPT2 charging port, (2) female USB to supply extra 5VDC power to external devices like HDDs. A user with an external HDD would then use the Y cable that came with their device to plug into both the USB port on the TPT2 and the female USB connector on this special cable.

 

All of this assumes that it's acceptable to require that higher power USB devices can only be used with the TPT2 where auxilliary power is available. That seems reasonable to me. If you need to use your TPT2 in  a truly portable mode then you probably don't want an HDD hanging off of it in the first place so a 32GB or 64GB microSD card or USB flash drive may be a better way to get extra storage.



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Please do not send me PMs. Ask your question on this forum so that everyone can respond or learn.

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226 Posts

10-08-2011

Florida

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Re: TPT2 has USB port power issue

2013-02-15, 16:19 PM

wrote:
The AC adapter that comes with the TPT2 can both recharge the TPT2 and power an external USB device like an HDD. (Admittedly that would increase recharge time based on the amount of 5VDC current that's diverted to the USB device.)

  ...

All of this assumes that it's acceptable to require that higher power USB devices can only be used with the TPT2 where auxilliary power is available. That seems reasonable to me.


Respectfully, I think we all understand at this point that external power sources of some type (dock, wall socket, USB from another device, battery pack, etc.) are an effective work-around, so we can stop beating that horse.  The focus of this thread is on powering devices from only the TPT2's ports if possible.

 

As far as the TPT2's comparatively diminished ability to power HDDs and ODDs (considered against comparable tablets) being reasonable, that's a matter of opinion.  I think that the assumption that the TPT2's USB port supports at least some external platter-style HDDs and optical burners is "reasonable," especially in light of Lenovo's marketing materials. 

 

But, has anyone on this thread successfully used any platter style HDD or any optical burner (recall Mark_Lenovo successfully used an old CD-ROM, not a burner)?  I am not yet aware of even a single such device working. 

 

To me, that is unreasonable, since Lenovo has not offered any such disclaimers, and in both promo demonstrations and their online datasheets have actually confirmed the opposite, that these devices can work with the TPT2.  Its not a dealbreaker for me, but I think Lenovo needs to say one way or the other as to whether there is a remedy to this defect or whether this is the design that buyers get, period.

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4682 Posts

12-22-2008

Canada

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Re: TPT2 has USB port power issue

2013-02-15, 17:19 PM

wrote:
Respectfully, I think we all understand at this point that external power sources of some type (dock, wall socket, USB from another device, battery pack, etc.) are an effective work-around, so we can stop beating that horse.  The focus of this thread is on powering devices from only the TPT2's ports if possible...

I think we can agree that for most people a cable such as this would address the issue.

 

I'm not suggesting that it's ideal but rather that it's probably more expedient and cheaper than an engineering change to the TPT2 itself. It's also more effective than some sort of disclaimer since that doesn't provide a solution or even a workaround.

 

BTW...

 

1. Do the makers of external HDD/ODD drives that require a Y-cable put disclaimers in their sales literature to explain why? In my experience they just say something like "USB powered, no AC adapter required" without mentioning that you might need to use up 2 USB ports.

 

2. I'm speaking here strictly as an individual TPT2 user.

 

 



My comments are mine. I don't work for or speak for Lenovo.
Please do not send me PMs. Ask your question on this forum so that everyone can respond or learn.

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226 Posts

10-08-2011

Florida

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Re: TPT2 has USB port power issue

2013-02-15, 17:40 PM

Respectfully again, the cable will not solve anything.  Having a separate power source connected by such a cable may remedy it, but that power source is likely not portable (like a wall socket), bulkier (such as a USB port from another device), and/or less reliable (such as a battery pack).  These options will provide a good work-around in many situations, but not in all situations. 

 

I'm hoping Lenovo will clarify whether this is permanent or can be "fixed" by a driver or sofware update.  In my opinion, this would be a "fix" because I consider this a broken design by Lenovo.  The admittedly anecdotal and not scientific evidence of this thread and of several recent tech-site reviews indicate that it is not merely a few HDDs or ODD-burners affected, but the majority (?all?) of such devices, even those which work reliably from a single USB port on other PCs and other W8 Atom tablets.  If it were "hit and miss" I'd be more inclined to think its devices operating outside the USB 2.0 spec.  But so far it's only "miss and miss again" since no one has posted success stories.

 

On that note, I'll again suggest that anyone whom has successfully used a non-thumb/stick style HDD or an optical burner from their TPT2's USB port please share this, along with details of the device.  If we can collectively start to identify such devices, it might warrant a stickied-thread of HDDs/ODDs that are known to work from the TPT2 USB port.

 

JC

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1808 Posts

08-17-2011

USA

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Re: TPT2 has USB port power issue

2013-02-15, 18:47 PM
I'm with you jchammerpants. Once again, Lenovo has delivered an inferior spec, while competing with other tablets that can do what the TPT2 can't do without extra cords or a dock. Unacceptable. Again, this is not a business device when compared, and no amount of extra cabling will fix that. Lenovo has already lost business sales due to this inadequate spec. I thought or hoped they would have learned from the TPT1 fiascos.
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