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So I bought an Amazon Basics powered usb hub in order to power 2 webcams and 2 mics. I don't have the mics connected, only 2 webcams.

So I plugged in the powered hub to my wall, and then the two webcams to my hub. Only one of them works, unless I lower my resolution to a whopping 144p.

I decided to unplug the hub from the wall socket, and the hub works in the same way. This leads me to believe that the wall power isn't even going through the hub.

Any ideas? Is there any specific product that you know works with multiple webcams?

Ignacio Cabero
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  • Did you plug the hub into the computer? Non An USB expert but USB only provides 100mA or 150mA (first for USB 1 & USB2, the 150 for USB3). Unless negotiated that it might draw more. Not sure if a hub can negotiate of just passes that info on to the computer. – Hennes May 09 '19 at 19:05
  • @Hennes yes it is plugged into the computer. Is there anyway to increase the amount of power outputted? The hub claims to provide 5V/4A of power. Would a 12V/3A one work better? – Ignacio Cabero May 09 '19 at 19:13
  • It should work precisly the same. USB was desgined to privide minimal power (100mAmp at 5v) for to power mimimal electronics. E.g. an pendrive, or the controller in a keyboard. If a device needs more power it should only draw 100MAmp (aka 1 bin) and then ask the computers if it pretty please may have more. Assuming the computer had spare power left it would might than grant that, or reply denying it. In an unpowered USB (fed from one USB cable) that would easily mean running out of power. In a powered USB hub that should not happen, – Hennes May 09 '19 at 19:26
  • But....that assumes everything follows standards (everything, not just the hub). The last is often hit and miss on USB. – Hennes May 09 '19 at 19:26
  • @Hennes So are you saying its possible that one of my devices (webcams, hubs, or PC itself) might not be working as intended? I think its weird that a hub that has 7 ports can only supply to one at a time... – Ignacio Cabero May 09 '19 at 19:30
  • It could have a defective wall wart or the hub could be defective. Try switching which port each web cam is plugged into, and try one web cam at a time. Verify that both web cams are working. Try plugging the web cams directly into the computer. Is the hub USB 2.0 or USB 3.0? To clarify Hennes' point, every device is initially allocated 1 unit load (100mA for USB 2.0, 150 mA for USB 3.0). If the device is not a low-power device, it negotiates for more current, up to the port limit. (cont'd) – fixer1234 May 09 '19 at 19:35
  • The hub negotiates directly with the device, it doesn't go through the computer. A self-powered hub (with wall wart), can supply each port with the full power defined by the USB spec. A hub powered only by the PC connection has to divide one computer port worth of power for itself and every device, so less than the one port maximum is available for sharing among all attached devices. – fixer1234 May 09 '19 at 19:35
  • Can you link to the product you actually purchased? Amazon product descriptions are not always accurate. – Ramhound May 09 '19 at 19:46
  • @fixer1234 I tried all of that and sadly nothing works. I've tried with 3 wall sockets, Ive moved the usb ports around. I even tried using a completely different powered USB hub and nothing seems to fix it. Is it possible its something wrong with my PC? Or one of the webcams? https://www.amazon.com/AmazonBasics-Port-USB-Power-Adapter/dp/B00DQFGJR4/ref=asc_df_B00DQFGJR4/?tag=hyprod-20&linkCode=df0&hvadid=167140037427&hvpos=1o4&hvnetw=g&hvrand=563353688258197611&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9023209&hvtargid=pla-283951041815&psc=1 – Ignacio Cabero May 09 '19 at 19:55
  • The purpose of moving things around and testing things individually is to rule out potential causes. For example, if you plug a web cam directly into the PC and it works, you know at least that the web cam is good, so the problem must be something else. With the wall sockets, if you plug a lamp into the socket and it works. Then you plug the wall wart into the socket and there is no power going to the hub, you know the wall wart is bad. (cont'd) – fixer1234 May 09 '19 at 20:03
  • The idea is to identify things you know work and then use those to test the next link in the chain. So moving a bunch of stuff around and "nothing works" doesn't really tell us much. It needs to be done in an organized, purposeful way that allows you to play detective. – fixer1234 May 09 '19 at 20:03
  • @fixer1234 Yes they both work when they are plugged into two usb ports on the computer. The problem comes when they are connected to the hub together. I moved them around trying every combination I could so it was pretty organized. When disconnected from the wall socket the behavior is the same so im led to believe that maybe power just isnt running through the hub. Its weird though because on my other usb hub it acts the same way – Ignacio Cabero May 09 '19 at 20:06
  • If you have a multimeter, you could check the voltage output on the wall wart. However, if it shows as working, it could also just be not as-rated and unable to support the load it's labelled for (you could check that with a resistor across the output terminals that is equivalent to the load it is supposed to support). It could also be a defective hub (they are notorious for being crap and have high failure rates). Check the hub to see if it has a switch that lets you select whether it is self-powered. It's possible that it has one and that switch is off, so the hub isn't accepting power. – fixer1234 May 09 '19 at 20:16
  • @fixer1234 Hub is probably just bad. Which is weird because I bought another amazon hub before which works great with usb devices but also doesnt work with the cameras – Ignacio Cabero May 09 '19 at 20:30
  • Are the cameras USB 2.0 or 3.0, and is the hub USB 2.0 or 3.0? – fixer1234 May 09 '19 at 20:32
  • BTW, check out this post on the off-chance it might help: [Using multiple USB webcams in Linux](https://superuser.com/q/431759/364367) – fixer1234 May 09 '19 at 20:39

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