RJ45?? Drivine me Insane - Page 1
Forum section: electronics / beginners

author: Domagoj T
author_rank: Frequent Contributor
timestamp: May 14, 2020, 10:17:04 am
content: So I have this device with what I presume is an 8 pin RJ45 connector, however, the pinout is all mixed up. What I would expect is the leftmost pin in the socket to connect to the leftmost pin on the solder side, second to second, and so on. On this connector, this is the pinout:The number 1 is the leftmost pin in the socket (note the latch is on top). I'm trying to find more of these, but either RJ45 is not the correct name for them or I'm just losing my mind. This thing is driving me insane. I went through basically the entire catalog of TME and didn't find this thing. As far as I can determine, it doesn't have isolation transformer (dead short on all socket pins and corresponding PCB pins).Please help, what am I looking at?

author: SL4P
author_rank: Super Contributor
timestamp: May 16, 2020, 04:48:26 am
content: Only you can tell if it’s an RJ45 compatible connector.Put a real CAT5 lead with a known RJ in, wiggle it around, then look at the continuity.The pin numbers you quote are arbitrary, it’s what you connect them to that makes it work.That staggered pin out is common, so you’ll find something within the first two searches.Where did your existing socket come from, is it an RJ45 8p8c - there must be a reference, or if you just need certified connectors, just buy and install.The hardest thing to match is the mechanical support pins.

author: AndyC_772
author_rank: Super Contributor
timestamp: May 16, 2020, 07:54:59 am
content: I'm going to make a guess here... tell me if I'm wrong.I think you've checked the pinout by plugging in an Ethernet network cable, and measuring from the PCB pins to the pins on the *other* end of the cable.Ethernet cables have four twisted pairs: 1-2, 3-6, 4-5 and 7-8. Within each pair it's permitted to swap the wires over.Your pinout would make perfect logical sense if pairs 1-2, 4-5 and 7-8 were swapped in the cable. The socket you have is, I'd be willing to bet, perfectly standard, with pins 1-8 in order.

author: Domagoj T
author_rank: Frequent Contributor
timestamp: May 16, 2020, 01:40:38 pm
content: Quote from: SL4P on May 16, 2020, 04:48:26 amIt is RJ45 compatible in mechanical sense. There are 8 pins in the socket, 8 pins on the PCB side, Ethernet connectors fit properly and make electrical connection. The fact that pins are staggered doesn't bother me. It's the fact that they are not in order.Unfortunately there are no markings on the socket. It was bought several years ago from a local brick and mortar store.Quote from: AndyC_772 on May 16, 2020, 07:54:59 amI checked the pinout without a cable (multimeter continuity between socket side and PCB side).While the cable used is Ethernet, the protocol for the device in question is S88https://dccwiki.com/S88so swaping pins around is not an option.Anyway, I decided to bin the existing boards I have and respin them around a standard socket. It's just a simple level shifter. These connectors were a pain in the butt years ago when we first came across them and I just decided that the continued suffering was not worth the few hours needed to fix them permanently.Thank you guys anyway.

author: tooki
author_rank: Super Contributor
timestamp: May 16, 2020, 08:49:25 pm
content: Quote from: AndyC_772 on May 16, 2020, 07:54:59 amWithout working it all out, perhaps it's a socket designed for the uplink port in a hub, i.e. a socket that performs the crossover function?

author: AndyC_772
author_rank: Super Contributor
timestamp: May 16, 2020, 09:38:02 pm
content: That would mean swapping 1-2 with 3-6, and I just can't see how it would ever make more sense to do that by changing the mechanical construction of the connector rather than just routing it differently on the PCB.I've certainly never come across an RJ45 with an 'odd' pinout like this, and I've spent way more time than I care to admit designing networking and other wired communications kit. The only type of connector I've come across where every one seems to be different is those that have integrated magnetics - but then there's no continuity between the socket pins and the PCB pins at all.Time to mill the top off the old one to see how it's put together?

author: Domagoj T
author_rank: Frequent Contributor
timestamp: May 17, 2020, 11:08:09 am
content: Quote from: AndyC_772 on May 16, 2020, 09:38:02 pmAsk and you shall receive.

author: AndyC_772
author_rank: Super Contributor
timestamp: May 17, 2020, 04:01:13 pm
content: Wow... evey day is a school day!That is indeed a very unusual connector, not something I've ever come across. Or maybe I have, but I've completely missed the pin swaps and ended up with a product that works anyway.Sorry I can't help identify what it is or where you might buy another one like it, though.

author: Domagoj T
author_rank: Frequent Contributor
timestamp: May 17, 2020, 04:07:42 pm
content: Thank you anyway.Like I said, I gave up on them and redesigned the PCB to accept regular stuff.I'm not a network guy but if you say that 1-2, 3-6, 4-5 and 7-8 pairs are swappable, than this looks to be it (except the 3-6 pair).

author: Raj
author_rank: Frequent Contributor
timestamp: May 23, 2020, 07:10:01 am
content: Quote from: Domagoj T on May 17, 2020, 11:08:09 amHmm...Big Clive's xray machineQuote from: Domagoj T on May 17, 2020, 04:07:42 pmQuote from: Domagoj T on May 14, 2020, 10:17:04 amIf you're using Ethernet plug for it's intended purpose, do know that only 4 out of the 8 wires are actually doing the work... The rest of em are intended for carrying future upgrades without rewiring... Like power over Ethernet, phone signal over Ethernet,2 Ethernet connection using single cable.It's the orange and green wires that actually carry signal.Ofc, not all Ethernet jack looking ports look the same... My gaming hotas uses all of the Ethernet wires to carry digial signal and power... Connect a normal net equipment to it, and I'll blow up

author: AndyC_772
author_rank: Super Contributor
timestamp: May 23, 2020, 07:15:36 am
content: 10/100 ethernet uses only 2 pairs, Gbit ethernet uses all four. If you're using power-over-ethernet, that can either use the data pairs OR the two spare pairs, depending on whether the power is supplied by the switch or by a mid span power injection device.What is "gaming hotas"?

author: Raj
author_rank: Frequent Contributor
timestamp: May 23, 2020, 07:37:46 am
content: Quote from: AndyC_772 on May 23, 2020, 07:15:36 amThanks for the added info...As opposed to simulation gear, it's a pair toy joystick and throttle made to resemble the real thing

author: mikerj
author_rank: Super Contributor
timestamp: May 23, 2020, 10:52:41 am
content: Quote from: AndyC_772 on May 23, 2020, 07:15:36 amHOTAS = "Hands On Throttle And Stick" which in aircraft terms just means that many controls are integrated into the throttle lever and and flight stick, as per any modern fighter etc. In gaming terms it means a joystick and throttle assembly with about a zillion buttons scattered around

author: tooki
author_rank: Super Contributor
timestamp: May 23, 2020, 11:14:46 am
content: Quote from: Raj on May 23, 2020, 07:10:01 amIn addition to what AndyC_772 already said, also know that some varieties of 100Mbps Ethernet that never caught on also used all 4 pairs.

author: Raj
author_rank: Frequent Contributor
timestamp: May 23, 2020, 11:18:05 am
content: Quote from: tooki on May 23, 2020, 11:14:46 amGood they didn't :pI would have had to rewire many things otherwise

author: MarkF
author_rank: Super Contributor
timestamp: May 23, 2020, 11:19:09 am
content: Quote from: mikerj on May 23, 2020, 10:52:41 amThese are USB though.

author: Raj
author_rank: Frequent Contributor
timestamp: May 23, 2020, 02:45:18 pm
content: Quote from: MarkF on May 23, 2020, 11:19:09 amOh..I mean the connection between the throttle and joystick being over enternet like socket....

author: MarkF
author_rank: Super Contributor
timestamp: May 23, 2020, 05:05:48 pm
content: Quote from: Raj on May 23, 2020, 02:45:18 pmNo ethernet.The throttle plugs directly into the stick.It's like a DB9 or DB25 connector. Can't remember any more.Then, the stick has USB connection to the computer.The pots inside are crap. We bought five units and three of the throttles didn't work.$300 USD several years ago. Don't buy!

author: Raj
author_rank: Frequent Contributor
timestamp: May 24, 2020, 04:34:19 am
content: Quote from: MarkF on May 23, 2020, 05:05:48 pmOh...I mean, my chinese hotas uses ethernet type plug....and yeah, everyone and their moms is complaining about potentiometer wear. There are literally hundreds of threads over onhttps://forums.eagle.ru/about how to replace them with hall effect sensor.