ajws7036
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Is this a good usb hub?

Mon Jun 03, 2013 1:34 pm

Hello, I just recently bought a 7-port powered usb hub, model HUB-036-2SV-p found here: http://amzn.com/B002FFZGCU, is this a good usb hub? i couldn't find any info on it because there's technically no manufacturer other than "OEM"... The reason i chose it was because i saw it as a reccommended hub in a linuxuser magazine with a Pi tutorial. I've got a Pi 512mb rev.2 with the Samsung PoP RAM chip, and mine has the mounting holes.

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Re: Is this a good usb hub?

Mon Jun 03, 2013 1:36 pm

YMMV
it will backpower the RPi
there are a few different versions in the same case
basically it works fine as long as you have a decent power supply
{I take mine to pieces and mount them in other boxes to power the RPi and provide extra usb]
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ajws7036
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Re: Is this a good usb hub?

Mon Jun 03, 2013 1:52 pm

So would it be a good idea to use it to power the pi via micro usb? and would I have to wait until I get it to see what version I have?

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Re: Is this a good usb hub?

Mon Jun 03, 2013 6:21 pm

FWIW, this variant (http://www.cpmspectrepi.webspace.virgin ... rtHub.html - bought via Amazon UK) had poor internal decoupling and a poor quality PSU (measured loading behaviour here: http://www.cpmspectrepi.webspace.virgin ... BHubs.html). Similar comments have been made in the wiki (http://elinux.org/RPi_VerifiedPeriphera ... m_USB_Hubs).
Trev.
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Re: Is this a good usb hub?

Tue Jun 04, 2013 4:29 am

I bought a similar one and the power supply that it came with was rubbish. Couldn't even power the Pi.
Used a Linksys SPA3102 power supply instead (5v 4A) and it runs fine.
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Re: Is this a good usb hub?

Tue Jun 04, 2013 8:00 pm

Those no-name hubs, once you get your hands on one, you may be able to see what chip they have from the Manufacturere and Product ID obtained from lsusb. And lsusb -v will give you much more information.

Sellers often do not know the chips, not for these off brands.

Yes, you can power the Pi by plugging a cable in taking power from the hub to the microSD power port. But it may not be able to deliver the 700mA the Pi needs.

I am very happy with a cellphone charger from Motorola, which was very cheap on Amazon and on the Verified Peripherals page.
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ajws7036
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Re: Is this a good usb hub?

Tue Jun 04, 2013 9:24 pm

Thanks! can't wait for it to come!

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Re: Is this a good usb hub?

Sat Jun 15, 2013 5:02 pm

So my usb hub came today, and it's been shippe with a 5v 1000mA power adaapter.. is that good? or do I need a better supply? I have access to a 7v 2a powersupply... but will that overpower the usb hub?

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Re: Is this a good usb hub?

Sun Jun 16, 2013 5:03 am

Whether 1000mA is enough depends on what you want to do with the hub. It should be enough to power the Pi, but very little else. Pi uses 700mA, that leaves you with 200-300mA left for the other ports. Might be okay to add some very low power usage devices, but not very many of them.

I have a hub with a 1000mA power supply and it can power one power hungry device but not two, and definitely not the Pi when my hungry devices (speakers or modem) are plugged in.

Check the power requirements of the devices you want to plug into the hub, that will tell you if it is enough... but...only if the hub delivers as much power as it says it delivers, and most deliver less. How much less is hard to say.

How much power do your devices need? Plug them into the hub (one at a time to keep from crashing the Pi by plugging more things in than the hub can power) and do lsusb -v to see how much power they say they need.

If you are not worried about cords and the number of peripherals, for about $3-$4 max you can get an excellent cellphone charger from Motorola from Amazon no shipping fee, and not have to worry about so many things needing to be powered by the hub. I do not know if the other adapter you have will hurt the hub, will be interested in seeing an authoritative answer to that question you have.
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ajws7036
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Re: Is this a good usb hub?

Sun Jun 16, 2013 7:57 am

Well powering the pi isnt such a big deal, i usually use my iHome. What i'm wondering is..
A. Will my 7.5v power adapter be able to power a wifi dongle (tl-wn725n),a bluetooth dongle (seemed to draw the most juice from the original adapter), a sata to usb adapter attached to either an 80gb hdd or a cdrom (that has its own supply),a sound card (c-media electronics,inc. ),and a logitech unifying dongle?

B. Will my 7.5v 2a power adapter be fit?

C. Can i power the pi alone from the backpower the hub sends to the usb ports?(if i have anough juice)

I apologize for my annoyance, i'm sixteen and new to the pi. Anything i've used before was a desktop or a laptop.

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Posted from a nook 1e, please excuse typos.

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Re: Is this a good usb hub?

Sun Jun 16, 2013 8:16 am

ajws7036 wrote:A. Will my 7.5v power adapter be able to power a wifi dongle (tl-wn725n),a bluetooth dongle (seemed to draw the most juice from the original adapter), a sata to usb adapter attached to either an 80gb hdd or a cdrom (that has its own supply),a sound card (c-media electronics,inc. ),and a logitech unifying dongle?
No You don't want 7.5V anywhere near 5V equipment. Only use it for things that are labelled as needing 7.5V.
B. Will my 7.5v 2a power adapter be fit?
No. You need a regulated 5V power adapter. Ideally with a minimum of 1A (1000mA). More Amps will not hurt anything as the equipment will only draw what it needs. More Volts will overload things.
C. Can i power the pi alone from the backpower the hub sends to the usb ports?(if i have anough juice)
Yes. As long as it isn't one of the first type of Rev1 boards that have 140mA fuses fitted as F1 and F2. Be aware that you will be bypassing the fuse F3 by doing this and it won't be able to protect the Pi if there is a problem with the power supply (or protect the power supply from a problem with the Pi).

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Re: Is this a good usb hub?

Sun Jun 16, 2013 8:26 am

Okay because when i did try to backpower the pi it keptgoing and out, and the pi alone seems not to be able to be powered from the hub backpowered or via microUSB. So should i get a better power supply? More amps, but stick with 5v. Correct? Any reccomendations for a better power supply?

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Re: Is this a good usb hub?

Sun Jun 16, 2013 10:04 am

About a better power supply, I said before, seeing that you live in Ohio, that you can get an excellent power supply for the microUSB port for the Pi by getting a Motorola cellphone charger from Amazon with free shipping and no minimum, the last I checked. There is just one listed on the Verified Peripherals page, and that is the one I got and I am quite happy with it.

http://elinux.org/RPi_VerifiedPeripherals

Deciding on a super good hub that is not expensive is not easy, I am struggling with the same question. A lot of people give rave reviews for the Plugable 7 Port hub that has a 2.5-3 amp supply, that would probably meet all your needs. I do not know about buying better AC adapter for your hub, and the Plugable is not cheap, about $20, but you can be sure that it will perform well.

I mentioned running the "lsusb -v" command. Do you know how to get to the terminal on your Pi to run commands? If you can do that and type those words without the quotes, the output will tell you more than you can begin to want to know about all the USB devices plugged in to your pi at that time.

To get just one screen at a time of the output, because the lsusb -v output is longer than one screen, you would type the following instead, the "less" command waits for you to hit a space before it gives you the next screen:

lsusb -v | less

And then you look at the names of the devices and then for lines saying MaxPwr to see the power the manufacturer says they might need.

EDIT: I see you do not need to power the pi, just peripherals. Was just looking at AC/DC adapters at Amazon for hub and the cheap ones look pretty iffy. Going to call my local electronics store to see if they have something more reliable that does not cost as much as a model A Pi.
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Re: Is this a good usb hub?

Tue Jun 18, 2013 1:27 am

the USB 2.0 specification clearly states (7.2.1 on page 171):
"No device shall supply (source) current on VBUS at its upstream facing port at any time."

so any one that has a hub that is feeding current back to the Pi should download the USB 2.0 specification (http://www.usb.org/developers/docs/), print out that page and take the hub back to the store and demand money back and suggest that the store recalls the hub and no longer sells it. and if the seller don't listen, tell them that you will contact the better business bureau or whatever authority that handles this type of issues where you live.

if enough customers will return the USB hubs that they bought in good faith that they actually were USB compatible hubs, perhaps the stores and distributors finally will get the message that it is no longer OK to sell USB hubs that do not meet the requirements.
perhaps one day we can instead of buying cheap products with bad quality, be able to buy low cost products with perfect quality. the cheaters are pushing good companies out of business by selling their crap at bottom prices while not even bothering to read the official USB specs or trying to design their products correctly.

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Re: Is this a good usb hub?

Thu Jun 20, 2013 8:06 am

For what it's worth, I have one of these 7 port hubs.

Have - I should say 'had': it's now in the bin. After less than a month three of the ports failed. Took it apart to see if it was fixable and was absolutely horrified at the shoddy workmanship that lay within. Cold solder joints everywhere, NO power decoupling at all, and will definitely supply more than 2.5A should the PSU have a bad day. It's at this point I also noticed they used a cheap trick to get the 7 ports: it's two four port hub ICs laid back to back. Cheap nasty ones at that.

So I decided to try and salvage what I could: added some polyester .22uf decoupling caps, cut a trace and added a diode to stop it backfeeding (would rather the polyfuse in the way than nothing at all). Reworked *every single last* solder joint on the board so they looked like shiny chocolate chips as opposed to grey rabbit droppings.

All went well until a week later when we had a power surge: the thing let out its magic smoke and that was that. Had I not added the diode the Pi would have done so too.

It's now humming along happily on a USB hub I made myself a while back, which does have decoupling, polyfuses, the works. Cost a pretty penny to make but at least I know what will happen if the worst should occur.

The moral of this story: if it doesn't have a brand on it (and sometimes even if it does) steer well clear of it...
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Re: Is this a good usb hub?

Fri Jun 21, 2013 9:19 am

ajws7036: If you take a good look at the reviews at the bottom of the page you linked to for this hub, you will see that most people reviewing it said that it is a very poorly made, unreliable hub. A basic rule when evaluating a purchase decision is to read customer reviews, no matter who you are buying from. I would guess you did not read further down the page, or you would have concluded that it would not be a wise purchase, without even having to ask here if it was any good.

I am not criticizing you, I just want to make sure that you learn this is one of the important things we have to do when we are shopping for computer accessories like hubs. Sometimes the place you want to buy from does not have reviews, so then the thing to do is to type the word "reviews" and the brand and model number of the item you are interested in, into google or another search engine's search box, and see what you can learn that way.

Our verified peripherals page needs more thorough coverage, so any folks with experience with hubs not on that page, please do add your experience to the wiki so that others not adept with searching the forum can find the information when making purchase decisions.
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ajws7036
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Re: Is this a good usb hub?

Sun Jun 23, 2013 8:42 pm

I ended up overpowering the hub, and so now it's toast anyways. I am however, now using a 7-port USB hub here:http://amzn.com/B007S642BW. It did not come with a power adapter, but I had a spare +5v 3a adapter from an unsupported belkin 7-port mobile hub. The New hub works great, it has switches for everything, and it backpowers the Pi well. Plus, it does not cause my pi to reboot when I turn on the wireless adapter switch. I also am able to run a Logitech unifying adapter, a CD drive connected via an IDE to usb adapter (powered externally with a 12v adapter, although it says it gets 5v from the hub), my tp-link wn725n wifi adapter, my c-media electronics inc sound card (used for a microphone, works great!) and an SD card reader all at once, and yet it still amazes me that it still backpowers the pi. Is there any caution I should take when backpowering? I understand that it doesn't pass the fuse F3, so should I stick to using a microUSB power source? And as for of purchasing a new power adapter for my pi, I continue to use my iHome. It supplies enough power to the pi, as well as serves as a fantastic speaker. So, In conclusion, I have a few questions.
  • Should I let the backpowering power the pi alone?
  • Is my 7-port hub alright?

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Re: Is this a good usb hub?

Wed Jun 26, 2013 11:25 am

Hey all,
Does anyone have experience with this one?
Person in the comments says it worked for him, but had backfeed.
Could I connect it just to the data pins and ground, and avoid the backfeed?

Guy

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Re: Is this a good usb hub?

Wed Jun 26, 2013 3:30 pm

That's a very generic 'China' hub. As others will point out it doesn't actually meet the USB spec because it shouldn't back feed. That may or not bother you depending on whether you want to use the back feed or deal with it by removing the +5 connection on the upstream cable. If you don't want to back feed there are hubs that do meet the spec in this regard. See the RPi verified periperals list for recommendations.

There are lots of suppliers of this 'China' hub which are all pretty much the same, but they do vary quite a bit in the power adapter bundled with it and that's what I'd worry more about here. This supplier says 0.5A which is basically worse than useless, although some of the comments seem to suggest they got 1.0A delivered. I'd choose a supplier who specified a decent supply with 2.0A capability or get that separately and throw the one that comes with the hub away. This type of hub will almost certainly have a 2.1mm barrel power input.

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