Dodgy USB hub - Page 1
Forum section: electronics / beginners

author: davidbrewer
author_rank: Newbie
timestamp: February 28, 2018, 03:33:44 pm
content: So I got a couple cheap USB hubs online and when testing them I noticed only one port works at a time, and if you connect devices to two ports and plug it in none work.I decided to open up and see what was inside, and it appears to have literally no components inside, but the silkscreen and pads are there!Has anyone ever seen anything like that? Can I fix it, and is there any way to find out which kinds of components/values I need to do so? I can see what I believe is a surface mount cap, an SMD cap and an SMD resistor, I don't know what the Y would be (a crystal maybe)? Somewhat blurry photos below.

author: glarsson
author_rank: Frequent Contributor
timestamp: February 28, 2018, 03:40:47 pm
content: You can mount anything as Y1. It is not connected to anything at all and will make no difference. This is not an USB hub as is clearly shown by the tracks connecting all USB pins of all connectors in parallel. This is just something that can distribute USB power to some more devises (lamps, fans, etc) or charge mobile phones.

author: davidbrewer
author_rank: Newbie
timestamp: February 28, 2018, 03:47:52 pm
content: Quote from: glarsson on February 28, 2018, 03:40:47 pmDamn, it was definitely being sold as a USB hub, oh well.So the missing components are just to provide some protection?

author: m_t
author_rank: Contributor
timestamp: February 28, 2018, 03:51:13 pm
content: Quote from: davidbrewer on February 28, 2018, 03:47:52 pmThe lower pads of R1 and C1 don't seem to be connected to anything either...

author: ArdWar
author_rank: Frequent Contributor
timestamp: February 28, 2018, 03:51:51 pm
content: A real USB hub will have multiplexer or controller chip of some sort. This "hub" however, obviously have none, and even populating the missing components won't make it works because they basically lead to nowhere. It won't even change the circuit behaviorThe only useful thing to do with this stuff is maybe as USB power distributor. Even then, it might not work properly if the power supply or receiver implement newer USB PD protocol strictly.

author: davidbrewer
author_rank: Newbie
timestamp: February 28, 2018, 03:54:54 pm
content: Quote from: m_t on February 28, 2018, 03:51:13 pmQuote from: ArdWar on February 28, 2018, 03:51:51 pmouchNow I'm wondering what would be the point of adding that to the board then...

author: Gyro
author_rank: Super Contributor
timestamp: February 28, 2018, 03:59:01 pm
content: I think it was originally designed as a forgery. With an electrolytic cap fitted as C1 and a crystal fitted as Y1, it would look like a genuine product from above (obviously not if you removed the PCB and found no Silicon or smt on the back). [EDIT: maybe it originally even had the two smd parts and a blob of black epoxy too].They then appear to have 'cost reduced' it!

author: paulca
author_rank: Super Contributor
timestamp: February 28, 2018, 04:14:47 pm
content: Would it work as an SMD solder practice board?

author: drussell
author_rank: Super Contributor
timestamp: February 28, 2018, 05:06:09 pm
content: LOL...A USB powersplitter^H^H^H^H^H^H^H^H^HHUB!

author: paulca
author_rank: Super Contributor
timestamp: February 28, 2018, 07:06:15 pm
content: Send it to these guys:

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: February 28, 2018, 07:22:37 pm
content: That's not a "USB hub", that's only good for charging two or three phones from a single USB socket, and only marginally good at that...

author: amyk
author_rank: Super Contributor
timestamp: March 01, 2018, 01:31:47 am
content: Very unusual. It's like someone took the PCB design from an actual hub, then erased all the active circuitry and just connected all the ports in parallel... but then that crystal would be too far from the IC, and a lot of hub ICsdon't evenneed a crystal to work(those two appear to be direct clones of each other, as the DL1049's datasheet clearly has the schematic's "MW7211" text sloppily overwritten with "DL1049".)https://www.eevblog.com/forum/reviews/teardown-a-really-cheap-4-port-usb-hub/On the other hand, this one discussed here recently, looks like it was never designed with any active circuitry:https://www.eevblog.com/forum/chat/fascinating-usb-hub-teardown/