Teardown -- a really cheap 4-port USB hub - Page 1
Forum section: electronics / general

author: RCMR
author_rank: Frequent Contributor
timestamp: April 05, 2013, 05:58:10 am
content: I've seen some dodgy Sino-gear in my time but this $6 USB hub takes the crown for "worst ever seen" by me.So I thought I'd share:

author: amyk
author_rank: Super Contributor
timestamp: April 05, 2013, 12:01:36 pm
content: At least they tried to make it a USB hub...http://www.flickr.com/photos/drug123/5127906425/#http://www.george-smart.co.uk/wiki/Cheap_CCY-01_USB_Hubhttp://jaanus.tech-thing.org/teardowns-and-reviews/gp3974-high-speed-usb-2-0-4-port-hub-for-laptop-480mbps-fake/

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 05, 2013, 12:56:37 pm
content: Just be glad it didn't come with a PSU... At least a shoddy hub won't kill anyone.

author: c4757p
author_rank: Super Contributor
timestamp: April 05, 2013, 01:20:31 pm
content: It really is awful that these are designed from the very beginning to be fake. I can see if they started as real hubs and then somebody in the factory decided to drop blobs of epoxy without installing the chip underneath, but with the ports paralleled on the PCB it's just too shady...The crystal footprint connected across +5 and ground

author: SeanB
author_rank: Super Contributor
timestamp: April 05, 2013, 03:27:26 pm
content: I did buy one, but i wanted it as an extender anyway, and it made it easier for me to do what I wanted to do, which was to supply an external supply to the USB device ( audio output) so that it would have a supply with lower noise.

author: ResR
author_rank: Regular Contributor
timestamp: April 05, 2013, 04:33:48 pm
content: I have one cheapy usb hub too, although for 4€ from around-the-corner shop in Märjamaa it do has a chip and a crystal and it works, for experiment I put 4 usb devices into that little hub including this cellphone Sony Ericsson Elm - where those picture came from, and they all worked. Unnamed brand, I removed the sticker when taked a look inside first time many months ago and the sticker is gone with model name. Lead-free solder looks awful though.

author: nuhamind2
author_rank: Regular Contributor
timestamp: April 05, 2013, 05:04:18 pm
content: I bought hub a few month ago for about 3$, it has crystal and qfp package chip. Out of curiosity I google it and found the datasheet and this chip has feature like " optimized instruction set for USB protocol". Do USB hub chip need that, I mean "instruction set " thing ??

author: SeanB
author_rank: Super Contributor
timestamp: April 05, 2013, 06:24:49 pm
content: I have a few that have a "feature" in that the power led flickers after it is on for a while. Poor led dies that have broken bonds and thus oscillate with thermal expansion.

author: amyk
author_rank: Super Contributor
timestamp: April 05, 2013, 07:30:11 pm
content: Another thought that occurred to me is that a USB hub is really more like a switch in the network, as you can get passive Ethernet hubs wired much like these fake "USB hubs".

author: peter.mitchell
author_rank: Super Contributor
timestamp: April 05, 2013, 07:45:32 pm
content: I have been using these for a little while, i like the small tails on them, means you don't have issues with big devices blocking other ports.A couple of decoupling caps, a couple of resistors, a crystal and a mini soicUnsure if flux residue (no corrosion yet) or that horrible yellow/clear glue you would find on older electronicsThey're pretty good.

author: paulvos
author_rank: Newbie
timestamp: April 06, 2013, 08:27:08 pm
content: WOW. Almost as bad as some of the Chinese multimillion installations I've encountered.

author: free_electron
author_rank: Super Contributor
timestamp: April 06, 2013, 08:55:01 pm
content: the manufacturers of those 'hubs' should be tracked down and nailed to the wall by their balls...

author: Monkeh
author_rank: Super Contributor
timestamp: April 06, 2013, 09:00:36 pm
content: Quote from: ResR on April 05, 2013, 04:33:48 pmPlease resize your photos. There is no point inlining images if they'restill too big to be displayed.

author: jahonen
author_rank: Super Contributor
timestamp: April 07, 2013, 07:02:34 am
content: Seeing this kind of stuff makes me wonder why on earth I worry so much about correct USB pair impedance when laying out a PCB containing USB tracesRegards,Janne

author: amyk
author_rank: Super Contributor
timestamp: April 07, 2013, 11:03:40 am
content: Quote from: jahonen on April 07, 2013, 07:02:34 amLow and full speed are not very sensitive to signaling conditions, high speed is.

author: free_electron
author_rank: Super Contributor
timestamp: April 07, 2013, 03:29:39 pm
content: Wait till you have to do a usb3 layout... That is really scary....

author: jahonen
author_rank: Super Contributor
timestamp: April 07, 2013, 06:11:54 pm
content: Quote from: free_electron on April 07, 2013, 03:29:39 pmWell, I just hope that USB3 signalling obeys Maxwell's laws of electromagnetism so I don't need to go to school again for USB3.Regards,Janne

author: tom66
author_rank: Super Contributor
timestamp: April 07, 2013, 06:46:19 pm
content: USB2 has error correction. I would not be surprised if these cheap hubs can cope with it but drop so many packets that the performance is poor... I don't see how else they can do it.

author: nukie
author_rank: Frequent Contributor
timestamp: May 10, 2013, 01:24:24 am
content: Im sure everyone can imagine who's the person making these USB hubs. They either work in an assembly line or one person completes a whole unit at a time. This example looks like the later. The person probably being paid for every unit produced and not by the hour so the number counts. It's just a job for the assembler and non of the persons business if the product fails or sells. Its probably packed by another person down the line. The price is $2, do you think we need an extra head for QC?

author: T4P
author_rank: Super Contributor
timestamp: May 10, 2013, 07:45:17 pm
content: Spend some really money, guys.http://dx.com/p/4-port-high-speed-usb-2-0-hub-black-white-60cm-cable-length-132870At least i bought 3 of them (3!) and they all worked. And they are quite solid as well

author: metalphreak
author_rank: Frequent Contributor
timestamp: May 13, 2013, 02:59:34 pm
content: I got some of the long 10port hubs off DX. They work fine and the soldering seems ok.Nobody makes a 10port USB hub chipset either... It's a 7port with a 4port connected to one of those!

author: Monkeh
author_rank: Super Contributor
timestamp: May 13, 2013, 03:06:16 pm
content: Quote from: metalphreak on May 13, 2013, 02:59:34 pmThere are no true 7 port hubs either, they're 4 port with a 4 port attached. There may well be ICs which do that internally, though.

author: T4P
author_rank: Super Contributor
timestamp: May 13, 2013, 05:20:07 pm
content: Well i'll just say it actually works with 7 devices attached

author: SeanB
author_rank: Super Contributor
timestamp: May 13, 2013, 05:36:30 pm
content: I have a lovely 7 port USB hub, works well, well made, has a provision for either bus or external 6V power, and a nice 3A regulator for the external power as well, along with proper per port power switches. Only reason I do not use it is because it is USB1.0 only.

author: amyk
author_rank: Super Contributor
timestamp: May 14, 2013, 10:42:42 am
content: Quote from: Monkeh on May 13, 2013, 03:06:16 pmPlenty of 7-port single-chip hub controllers:http://www.smsc.com/Products/USB/USB_Hubs/Standalone_USB_Hubs/USB2507http://www.ti.com/product/tusb2077ahttp://pdf.dzsc.com/GL6/GL652.pdfhttp://www.zxkdznet.com/download/FE2.1.pdfOdd that once you go past 7 there don't seem to be any...

author: Monkeh
author_rank: Super Contributor
timestamp: May 14, 2013, 10:46:29 am
content: Quote from: amyk on May 14, 2013, 10:42:42 amAnd they're all actually two four port hubs internally. That's why they have seven ports.There's a reason they're arranged that way, too, and the TI datasheet there touches on it.

author: amyk
author_rank: Super Contributor
timestamp: May 14, 2013, 09:19:00 pm
content: Quote from: Monkeh on May 14, 2013, 10:46:29 amNothing obvious stood out at me on TI's datasheet except "supports a maximum of 4 downstream ports"... I should go read the USB spec a bit more when I have the time.

author: metalphreak
author_rank: Frequent Contributor
timestamp: May 15, 2013, 04:06:55 pm
content: It enumerates as a 7port usb hub with a 4port usb hub attached. What they do inside the chip I don't know, but it appears to windows as a 7port hub. 4->4 to get 7 makes sense if there is some kind of USB spec limit, but its hidden from the host pc.

author: amyk
author_rank: Super Contributor
timestamp: May 17, 2013, 07:08:16 am
content: It does not appear to be a protocol limit; just looked through the USB spec at the hubs section and they can theoretically allow 255 ports on one hub. I guess it might have more to do with physical limits on chip layout and complexity (some of the descriptors change in length past 8 total ports upstream+downstream) --- and the fact that most people do not need that many ports.Also see here.

author: T4P
author_rank: Super Contributor
timestamp: May 17, 2013, 09:12:01 am
content: Quote from: amyk on May 17, 2013, 07:08:16 amMore is better, on a single hub. I bought a 7 because desktop rear ports are a bugger to get to (I have 8! on the back panel alone) but also i was on a laptop before that and i needed way more than 4 and 2 4 ports would be unsightly ... and most 4 ports are a heap of shit

author: Monkeh
author_rank: Super Contributor
timestamp: May 17, 2013, 03:21:54 pm
content: Quote from: amyk on May 17, 2013, 07:08:16 amYou hit it: Power.You can only have four ports on abus-powered hub.Quote from: T4P on May 17, 2013, 09:12:01 amNo, more is most definitely worse.

author: T4P
author_rank: Super Contributor
timestamp: May 18, 2013, 05:00:54 am
content: But it's powered, dude.

author: amyk
author_rank: Super Contributor
timestamp: May 18, 2013, 11:03:27 am
content: Quote from: Monkeh on May 17, 2013, 03:21:54 pmYou mean bus-powered? Self-powered hasn't that restriction.

author: Monkeh
author_rank: Super Contributor
timestamp: May 18, 2013, 11:45:37 am
content: Quote from: amyk on May 18, 2013, 11:03:27 amSorry, yes, bus powered.Must be awake when posting.Quote from: T4P on May 18, 2013, 05:00:54 amIt's not always powered, dude.

author: metalphreak
author_rank: Frequent Contributor
timestamp: May 18, 2013, 01:43:10 pm
content: Makes sense to only have four. IIRC, a USB device can pull 100mA before it has to tell the host what power it requires. 100mA for the USB hub itself, 4 ports at 100mA, and you're at the USB "standard" capacity of 500mA. This one has a DC jack for self-powering but works fine without it as long as you stay within the limits of the host port. Many new PCs these days can provide 1A or more.

author: T4P
author_rank: Super Contributor
timestamp: May 18, 2013, 01:44:25 pm
content: Quote from: Monkeh on May 18, 2013, 11:45:37 amI mean powered BY a adapter, they give you an option to use a adapter. It's there if you want it, ANYWAY pulling 1amp over 7ports is possible. Most motherboards allow you to pull 1A now only gigabyte motherboards allow you to pull 1.5A PER PORT. Not GROUP. PORT. Unless you're stuck in Y2KQuote from: metalphreak on May 18, 2013, 01:43:10 pmBS, by those standards my device won't be able to pull 1A but IT DID.

author: Monkeh
author_rank: Super Contributor
timestamp: May 18, 2013, 01:46:47 pm
content: Quote from: T4P on May 18, 2013, 01:44:25 pmAnd if you don't use it, you can only have four ports. What about this are you having trouble grasping?QuoteWhich is not part of the standard USB specification an- oh, why am I bothering?QuotePlease at least skim the USB 2.0 specifications.

author: T4P
author_rank: Super Contributor
timestamp: May 18, 2013, 02:23:11 pm
content: Quote from: Monkeh on May 18, 2013, 01:46:47 pmAnd if you don't use it, you can only have four ports. What about this are you having trouble grasping?QuoteWhich is not part of the standard USB specification an- oh, why am I bothering?Please at least skim the USB 2.0 specifications.But does any manufacturer follow the specs? None. Nada. Zilch.Which is why it's all BS about not being able to pullwithout negotiation. My 5V USB fan testing rig pulls over 600mA without hesitation

author: elgonzo
author_rank: Unknown
timestamp: May 18, 2013, 02:38:53 pm
content: Quote from: T4P on May 18, 2013, 02:23:11 pmUSB 2.0: min. 500mA withoutnegotiationUSB 3.0: min. 900mA withoutnegotiationPorts implementing Battery Charging Specification (1.2): min. 1.5A, max 5A(EDIT: of course specifications define min. current delivery requirements for ports, not max. current)Ports that only fulfill USB 2.0 spec. are only required to deliver 500mA withoutnegotiation. Who would have thought about that???So, T4P, stop using abbreviated words like BS. It just makes you look like someone who is either too stupid to use Google, or just ignorant/unwilling to read specs. Or probably both...

author: Monkeh
author_rank: Super Contributor
timestamp: May 18, 2013, 02:40:31 pm
content: Actually, max 100mA without negotation and 150mA for USB 3.0. Battery charging specification is optional and cannot be assumed on host or device, and thus is utterly irrelevant.

author: elgonzo
author_rank: Unknown
timestamp: May 18, 2013, 02:49:22 pm
content: Quote from: Monkeh on May 18, 2013, 02:40:31 pmYou are correct.

author: T4P
author_rank: Super Contributor
timestamp: May 18, 2013, 03:28:20 pm
content: Go ahead and believe your stupid beliefs. I know it's written in USB specs i know it before from all your arguments here in the past BUT NO MANUFACTURER FOLLOWS IT.Tell me if USB fans have any way of negotiating with the USB port. I draw 600mA so i don't know what you're on about

author: Monkeh
author_rank: Super Contributor
timestamp: May 18, 2013, 03:37:50 pm
content: Quote from: T4P on May 18, 2013, 03:28:20 pmYou're totally missing the point. I don't care if you can draw 600mA (you try that on actual compliant hardware, see how you go. Your 'USB' fan is, by definition, not USB), the hubs are arranged as chained 4 port hubsbecause of the USB specification. Unlike your cheap toy, they're actuallydesigned.

author: metalphreak
author_rank: Frequent Contributor
timestamp: May 19, 2013, 07:34:33 am
content: If you read the specification...Thedeviceis expected to comply with the standard. The HOST has no control over what power is drawn.Your one hung low USB powered fan is not compliant with the spec and will never get official USB certification. Does the manufacturer care? no.A large IC manufacturer of USB hub chipsets does, otherwise they can never sell their parts to customers who do want their products to be certified.Apple, Samsung, Motorola et al phones will only pull 500mA from a PC or charger UNLESS, its told it can draw more. Chargers use resistors across the data lines for this. GIGABYTE uses a similar technique to enable the 1.5A charge on their motherboards. You have to install a modified INF driver file to enable it. This is only to tell those devices that would normally follow the spec they can draw more. You can happily plug in your 1.5A USB coffee warmer if you want with no issue.

author: SeanB
author_rank: Super Contributor
timestamp: May 19, 2013, 12:45:43 pm
content: I actually bought the cup warmer, it was on sale for $1, so not a worry if it was going to not work. Just cut the wire for the 2 0.5W resistors stuck to the top with heatsink compound ( and cleaned it off as well) and it works as a regular hub, and not too bad at that either.

author: AFK
author_rank: Newbie
timestamp: January 19, 2014, 08:35:05 am
content: A couple of things to add regarding power.Quote from: metalphreak on May 19, 2013, 07:34:33 amMany USB host controllers provide over current protection and do limit what power is drawn. Theprotection circuitcan either protect each individual port or all ports combined (ganged). A four port ganged protection circuit should trip when 2+ Amps is pulled (4 x 500mA). Ganged protection is obviously cheaper and, thus, probably(?) used more often. This may help explain why T4P and others are seeing compliant devices allow more than 500mA to be drawn. I'm no USB expert, but the few cheap USB ICs that I've seen use ganged protection.I recently bought a $15 USB 2.0 hub from a reputable local computer store recently and was very disappointed that it never surpassed USB 1.x speeds (12Mbps). Long story short, the makers of the hub used a USB 2.0 IC and followed all of the sparse recommendations in the datasheet, but knewnothingabout high speed layout practices. It didn't help that the assembly was as bad as the designFull teardown:http://blog.olkie.com/2014/01/16/cheap-usb-hub-teardown/Windows USB debugging that lead to teardownhttp://blog.olkie.com/2014/01/16/link-depot-usb-hubs-suck/

author: amyk
author_rank: Super Contributor
timestamp: January 19, 2014, 11:59:42 am
content: Apparently a$1k thermal imaging cameracouldn't care less about the USB current limits either, if those measurements are to be believed...