Identifying safe/unsafe USB hubs? (Flash drive fried in hub.) - Page 1
Forum section: electronics / general

author: lpc32
author_rank: Frequent Contributor
timestamp: March 21, 2014, 07:22:07 am
content: How would one identify a USB hub as safe/good vs. potentially dangerous?I just got this cheap 7 port USB hub. I started by checking the ports with a USB flash drive (edit: while being just bus powered). The first port was okay, the second had Windows complain about an unknown device. Further checks revealed the USB drive is no longer recognized (but its insertion is identified), also without the hub, or on another computer.It's a flash drive I've been using occasionally for several years without an issue, so I think the hub is to blame. I didn't test the hub further lest it fry something else.Do you see anything obvious in the PCB that might fry connected devices? (Various things look fishy, but anything to lead to killed devices?)Can anyone recommend a decently laid out, cheap, powered, 7-port hub off eBay or a China/Hong Kong online store?The board is in a shiny/reflective plastic case (didn't get it from this store):

author: SL4P
author_rank: Super Contributor
timestamp: March 21, 2014, 07:25:32 am
content: Unfortunately you had to open it to see the pretty awful soldering...I have a neat Belkin desktop USB2 hub that has been plugging along for several years now.

author: PeterG
author_rank: Frequent Contributor
timestamp: March 21, 2014, 07:33:36 am
content: I remember reading about someone who used the wrong plugpack to power one of these. Turns out, windows did not complain but there was 12v on the power rails for the out going usb ports. He destroyed several usb drives before discovering this.I would check the voltage of the supplied plugpack.Regards

author: lpc32
author_rank: Frequent Contributor
timestamp: March 21, 2014, 07:37:23 am
content: It was just bus powered (edited the original post to mention that).SL4P: How does it look inside?

author: SL4P
author_rank: Super Contributor
timestamp: March 21, 2014, 10:55:55 am
content: lpc32:re: Belkin hubSorry - it's all back together...It's a powered hub, with 5 ports on the back, and 2 on the top for memory sticks etc. Internally a single PCB with 7 activity LEDs across the front, and a green power LED. About 5" wide, 3"deep, and 3/4-inch high.

author: SeanB
author_rank: Super Contributor
timestamp: March 21, 2014, 11:21:56 am
content: I have some similar Belkin hubs, but my ones are older 4 port ones similar in shape to a hockey puck. Only issue was the original USB cable was a right angled one that was front facing on installation ( why? Better to go the other way so you do not have a cable loop to the front) and a finish that is that soft feel plastic that turns to goo with time. other than that a good hub with a decent power supply. Was about $40 when I bought them.I have a lovely USB1.0 7 port hub as well, which works perfectly, but is not usable as it is still USB1.0 so data transfers take hours to days.

author: amyk
author_rank: Super Contributor
timestamp: March 21, 2014, 12:16:23 pm
content: Check the VBus coming out of the PC, sometimes they can go slightly high (nearly 6V) due to the PSU in the PC, and killing a flash drive just because of the hub could be a coincidence.A Vbus to DM/DP short (due to debris in the connector, etc.) mightbe a possible cause, but more robust USB devices should survive that.

author: lpc32
author_rank: Frequent Contributor
timestamp: March 21, 2014, 03:13:23 pm
content: I'm wondering what makes a good hub PCB layout. I just don't know what circuit elements to look for.SL4P,Sean, those Belkins, do you judge them based on the actual circuit or just the fact that they seem to work?I don't think you'd usually run into problems even with "unsafe" hubs. For example, I have the below 4 port hub. No problem so far (though, I've mostly used it with self-powered devices, which I assume are beefier and more likely to have protection). The layout of this hub doesn't look too inspiring either, but then again, what do I know.$40 for a hub is far too much. The hub in the first post could probably be made safe with an extra $1 worth of components. I was also looking specifically for a small PCB, 4-5 horizontal ports next to each other, the rest from another side. Besides the frying, another negative with the fishy hub is that it uses two 4-port hub chips instead of a single 7-port one.amyk: I never had problems with devices connected directly to the computer I tested the hub on. Vbus on the hub powered from the computer is 5.1V. The port I used to connect the hub is off a PCI card, BTW. Can you think of failure reasons other than overvoltage? I guess coincidence is possible but I've never had a USB device die, and this one did just when I was testing the new hub.

author: SeanB
author_rank: Super Contributor
timestamp: March 21, 2014, 03:29:20 pm
content: I pulled it apart, and it uses decent capacitors ( replaced some this year just because it was apart and I had some spare caps that would fit, and the hub is getting old so would be due for a recap at some time) and proper protection on the ports, though only 2 PTC fuses - 2 ports per fuse, along with decent soldering. Power supply is decent as well, has been on permanently now for about 4 years.It is powered from the filtered side of the mains though, not direct to the raw side but after a filter, so that may have helped.

author: SL4P
author_rank: Super Contributor
timestamp: March 22, 2014, 02:55:17 am
content: I bought my BELKIN 7-port hub based on the brand (usually reliable), and the USB2 (fast at the time) with easy to access top connectors for casual plug-in devices.It's been reliable and effective - it must be around 6-7 years old now - and going strong.

author: xtv
author_rank: Contributor
timestamp: March 22, 2014, 03:12:49 am
content: It doesn't look to have an ~5v regulation circuit onboard for powering the usb ports..You're probably relying on the external power supply. Have you checked it's voltage / vdrop?Maybe a DIY transformer power adapter with a LM317 (or even a couple of LM7805 ) and good caps would be far more stable than cheap chinese switching psus..

author: lpc32
author_rank: Frequent Contributor
timestamp: March 22, 2014, 11:52:28 am
content: xtv, it was just bus-powered.I think decent hubs might have something like an overvoltage protection chip, maybe overcurrent, and some diodes for ESD protection.Too bad product specs on eBay don't include schematics.

author: amyk
author_rank: Super Contributor
timestamp: March 22, 2014, 01:19:55 pm
content: ESD is another possible cause, as you mentioned "shiny plastic".

author: lpc32
author_rank: Frequent Contributor
timestamp: March 23, 2014, 02:23:09 pm
content: Quote from: amyk on March 22, 2014, 01:19:55 pmYeah, perhaps. But still something the hub's expected to handle.I tested another sacrificial USB flash drive. It worked fine on all 7 ports. Doesn't say much, though. It was also a rather bulky and old USB 1.0 device, so perhaps with better protection, inherent or by design, than the smaller USB 2.0 device I tested the hub with initially.BTW, interestingly, this USB2517 eval board has the all data lines connect directly to the controller chip:

author: SArepairman
author_rank: Frequent Contributor
timestamp: March 26, 2014, 08:19:26 pm
content: could you guys recommend a nice hub ?I am looking to buy something...

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 26, 2014, 11:36:44 pm
content: I have an IOGear wired/wireless hub that's very good quality, but I don't think they're available anymore. I also had great luck with Startech USB3 hubs, but I don't actually have one to tear down (the ones I used were in a work environment), so I can't comment on build quality.

author: lpc32
author_rank: Frequent Contributor
timestamp: March 27, 2014, 12:49:51 pm
content: My impression is that common options that may be okay are Belkin and D-Link, but I can't attest to that firsthand. Maybe someone can post internal shots of hubs from these companies?

author: Jarrod Roberson
author_rank: Regular Contributor
timestamp: March 27, 2014, 01:05:05 pm
content: You didn't mention the price of the hub or the drive that burned upThat said, I see a false economy in using a cheap no name chinese USB hub with $40US+ USB drive.And cheap non name USB drives are no better, I got a few for free in the past and everyone one of them burned up and stopped being recognized at exactly the worst time possible. And I don't use cheap USB hubs or cables. You definitely get what you pay for with stuff like this.

author: lpc32
author_rank: Frequent Contributor
timestamp: March 27, 2014, 04:00:10 pm
content: Both cheap. But the UFD was just fine for years, so I don't think it's the one to blame.In this specific case one goal with the hub was having a certain layout and size, so there are less options. But even so, the next step up (what's readily available locally and that I *think* might be better) is $35, which is way overpriced. But anyway wrong layout.