Question Question regarding safety of USB Hubs

fseveco

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Mar 11, 2018
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Greetings!

I have a bit of a problem on my sleeve, and that is that I accidently fried (to some degree) my MOBO on my new laptop.

It happened unexpectedly, I bought USB HUB Asonic 7 Port and it worked perfectly fine, however I lost the AC (Power Adapter for the usb hub) and decided to get a custom one from my local shop (which is Adapter switch. DC 3-12 V 1A) and when I plugged that custom Adapter into my USB Hub, and then into the usb port of back on my laptop, it fried one usb port whilst one kept working normally and the third one seems to be working but on half the power for some reason (I know this since when I plug my mouse or anything that glows it only glows with 50% light capacity).

Sent it to service and they're gonna fix it for free since it has warranty (they will replace entire motherboard) but I'm a bit worried.

I bought
UH700 Usb Hub (which apparently has some form of protection if you scroll on this site) after I've sent it to service cause I don't want to use the previous USB Hub just to make sure it doesn't mess up my laptop after repair, so my question is:

Can this new USB hub (UH700) damage my laptop again after it gets back from the repair, since it has 12v power from its AC and the USB supports only 5v, or was it just me combining two items that don't belong together that actually did the trick of frying the mobo through usb?
 
Last edited:

fseveco

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Mar 11, 2018
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Sorry moderators, I posted it on the laptop forum, can anyone help me with it on this particular section? Many thanks!
 

hang-the-9

Titan
Moderator
I have never fried a motherboard with a USB hub, but have seen USB issues fry motherboards. As long as the replacement power supply matched the specs of the one that came with the hub, including polarity of the power tip, that should not have caused the issues. No real good way to know for sure though, sometimes things just fail and cause funny surges to the USB power. I've seen people being lazy and shoving a USB cable into a motherboard at an angle and frying the motherboard.
 
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fseveco

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Mar 11, 2018
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I have never fried a motherboard with a USB hub, but have seen USB issues fry motherboards. As long as the replacement power supply matched the specs of the one that came with the hub, including polarity of the power tip, that should not have caused the issues. No real good way to know for sure though, sometimes things just fail and cause funny surges to the USB power. I've seen people being lazy and shoving a USB cable into a motherboard at an angle and frying the motherboard.
Thanks for the reply!

I think the custom AC i bought after I lost the original was approximately close to the original one, the original one was 1A and I think the replacement, custom one was 1.5A if I'm not mistaken.

My main concern is now that after the laptop gets back from the repair shop and I use my new UH700 Usb Hub that everything is safe (if I'm going to use AC for UH700 usb hub, which has 12v apparently).
 

hotaru.hino

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If the hub was designed properly, it doesn't matter what its input voltage is for supplementary power as long as the AC adapter is providing the correct DC voltage as the input. The hub should be designed to make sure the voltages for where it matters are what they are.

Not sure what your old USB hub was doing, but if the output of that custom AC adapter was variable, then I ask: how does it know what correct voltage to give the USB hub? For all I know, it operated at max voltage and somehow managed to feed that directly to the PC.
 
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fseveco

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Mar 11, 2018
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If the hub was designed properly, it doesn't matter what its input voltage is for supplementary power as long as the AC adapter is providing the correct DC voltage as the input. The hub should be designed to make sure the voltages for where it matters are what they are.

Not sure what your old USB hub was doing, but if the output of that custom AC adapter was variable, then I ask: how does it know what correct voltage to give the USB hub? For all I know, it operated at max voltage and somehow managed to feed that directly to the PC.
That's a good question though, but I don't know the answer on that part :)

Thanks for the help guys, so everything should work just fine with the new hub on my new motherboard once it gets back?

Also, if it somehow gets broken again, do you guys think that I should request a new unit (laptop) since repairs take like a month or so for these type of things...
 

ultrarunner100

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Dec 24, 2011
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It's been a few weeks since the OP posted this, but I am curious to know how things worked out.
So long as the voltage from the AC to DC adapter is correct, then using with a higher current capacity will not harm the hub or the computer. The hub will draw as much as it needs at the correct voltage. Using a supply with a higher than specified voltage will damage the hub, and could conceivably damage the computer. It all depends on how well the hub is designed. If there is an internal voltage regulator between the DC input and the components, then it will regulate whatever voltage is present at the input jack to the proper voltage for the components, within reason of course.
Most of the USB hubs I have seen require 5V input, but 12V is not uncommon, as it would be regulated down to 5V inside.
What will also affect performance is AC ripple. That's the amount of AC waveform present on the DC output. If the supply you purchased is of poor quality, it may not be well filtered, and therefore produce more AC ripple than is acceptable. However, it would have to be a really BAD supply, as it doesn't take much to produce a decent SMPS (switching mode power supply) these days.

Lastly, I would always connect the DC plug from the power supply to the device (the hub) before plugging the supply into the AC mains. This can prevent spikes on the DC side.
If you have a multimeter, you should also check the output voltage and polarity before plugging it into the hub. That said, some really cheap power supplies will not perform properly without a load, so the voltage you read on the DMM may be different than what will be supplied under load. But that would be a really cheap PSU, and I would avoid such products.
 

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