USB 3.0 wiring questions - Page 1
Forum section: electronics / beginners

author: meener777
author_rank: Newbie
timestamp: June 27, 2022, 03:54:54 am
content: Hello, I am trying to relocate a USB 3.1 type B receptacle from the front of a rack mount hub to the back so I dont have to look at the uplink cable. This has gotten a little more difficult than I expected... I need some help with a few questions, I am sorry for the complex post, trying to be complete and clear.The plan was just put a port on the back and wire it up. I ended up getting the mechanical part done with a dremel and a keystone wall plate i bought on amazon which i took apart and used as a routing jig (came out perfect, kinda proud of that mod!). Then I attached one of these keystone adapters to fit inside of the unit:https://www.amazon.com/gp/product/B00BS2YFVO/The keystone wall adapter unit has USB 3.1 type B on both ends, I am assuming it is straight wired before I remove the original USB 3 receptacle from the hub's PCB I stripped a cable on the end I was going to use to solder to the board and plugged in the USB type B end to the original receptacle, then used my multimeter to check continuity on the pins on the bottom of the board to see which ones hooked up to what. I wrote this down.Now, solder this together has gotten to be pretty hard, its tiny in there, but I want to get some questions squared away before I go any further because I am confused about a few things regarding the pinout.Assumption: The type B receptacle looks just like this one from mouser and I am assuming that the 9 pin through hole configuration is the same for other receptacles? Is this a bad assumption (see question 1)?https://www.mouser.com/datasheet/2/215/950-742485.pdfAssumption: I am also using this for the pinout meanings, type B pinout and assuming USB 3.0 is the same pinout as 3.1(NOTE: the Keystone type B receptacle whose datasheet I am referring to for the PCB pinout is a _different_ part from the keystone wall adapter I used for the back port on my mod, I will try to say "keystone wall adapter" if Im referring to that object which I bought on Amazon, otherwise Im referring to the keystone PCB mounted receptacle from mouser which I am only referring to the datasheet for pinout physical layout)Q 1: When I did my continuity test the pinout I got does not match the one in the keystone pcb receptacle's pinout layout (see datasheet under "RECEPTACLE FOOTPRINT"). Pins 5 and 6 were swapped and so were pins 8 and 9. Could that be due to a difference in the way the pcb receptacle is pinned or are all these receptacles using the a standard pinout? Otherwise I am wondering if it has something to do with twisted pairs, are they swapped on the receiving end? I am pretty sure I did not measure the continuity wrong four times. Trying to avoid having to solder these tiny .7mm holes twice.Q2. When I did my continuity test, pin 7 (per the keystone receptacle datasheet physical layout) was connected to BLK, the same wire as connected to pin 4. I am not if this is right since this diagram calls the "color" of this pin "ground". Does anyone know what this diagram might mean by "ground" color? Is it safe to just hotwire it to BLK?Q3: The USB 3.1 cable I have for the inside of the unit (from rear type B keystone *wall adapter* to the PCB board where I removed the type B pcb receptable) has a lot of silver wire around the inner wire components. Usually when I see complex high throughput cables (e.g. catlike this I do nothing with this outer wire. By any chance should I do something with this part of the wire?

author: meener777
author_rank: Newbie
timestamp: July 07, 2022, 11:18:43 pm
content: Hey all, sorry my previous post I know it was very long. Just trying to be clear about what I need. Im not an EE person but I feel like I should be able to wire up this USB port. But I cant seem to get to work. Ive included a couple of photos that will hopefully show what is happening here. Fundamentally, I have rack USB 3.0 hub and I am trying to move the uplink to the back of the unit. I've installed a wall receptacle in the back of the unit which has a Type B connector on both sides (see first photo). Ive remove the PCB receptacle. Now, in theory I think that if I wire up this internal USB 3.0 type B cable to the PCB and plug it into the back of the wall plate it should work but so far, no luck. I could really use some help if someone has the time.Notes:1. On the picture of the PCB, this is the _bottom_ of the board. So you are seeing things reversed wrt left right.2. I have just tried swapping the Blue/Yellow (pins 6/7, StdA_SSTX-/StdA_SSTX+_) and Purple/Orange (pins 9/10, StdA_SSRX-, StdA_SSRX+) to see if there was an uplink reversal needed but this isnt working either.Fundamentally if anyone can explain to me where the wires need to go, from the top-side view at least (I can figure out how to reverse it) I would really, really appreciate it.Thank you in advance!

author: tooki
author_rank: Super Contributor
timestamp: July 07, 2022, 11:46:26 pm
content: USB has pretty strict wiring requirements, so even if you have correct continuity, it’s not going to work with random wires soldered all over the place. Especially USB 3: within a differential pair, you have to length-match the two conductors to within 0.13mm. There’s absolutely, categorically no way you can achieve that this way.

author: meener777
author_rank: Newbie
timestamp: July 08, 2022, 03:48:46 am
content: Oh man, that is a big bummer. Okay, so if its not salvageable okay but is there any way to salvage it?I tried to buy a vertical receptacle for to just rotate the plug, it might not fit inside the 1U rack but my only goal is not have a some ports on the front my rack and not have to have the uplink always uglying up the front of the rack. Unfortunately when the part arrived, it had a _slightly_ different hole dimension than the straight receptacle. I assume this done on purpose so folks cant use the wrong part? In any case it was a bummer too.What about building a PCB board from the straight receptacle footprint to the vertical receptacle footprint? Is this ridiculous? Am i just slicing dirt here?