repairing an ethernet cable

The end connector came off. The telephone jack on steroids thingy. The wire is long, about a 50 foot run. Its pretty inaccessible, in the wall and floor.
We got some of the RJ45 connectors, but, how do you get the wires into it in the right order? It looks like reconnecting human nerves might be easier (But, wouldn’t really solve our problem)
Any advice, comments, cat calls, for the person who tripped over it. (yes, me. :rolleyes: )

if it’s a straight-through cable, meaning it’s used to connect a PC to a hub or switch and not a crossed one for connecting 2 computers directly to another or connecting 2 hubs or switches directly to another, you can just order the wires in the same way they are in the other end. I dunno if you can secure a RJ45 connector without the crimper tool you normally use, but possibly you could stick the wires in, then press down hard on the little plastic thingy with a screwdriver or something like it.

To pin a straight cable, you pin them the same on both ends. Straight cables connect computers to hubs (or smart hubs to smart hubs). For crossover cables, both ends are the same except you switch pins 3 and 6 on one end. Most likely, you want a straight cable, unless you know differently.

You have to know what the pin numbers are on the jack. Check with your manufacturer to be sure. You also have to know the number of the cable wires. Find out by looking at the other end… If you don’t know, you can try the AT&T standard, which is most common:

Wire PIN

White Blue 5
Blue 4
White Orange 1
Orange 2
White Green 3
Green 6
White Brown 7
Brown 8
Hope this helps.

As a “backyard mechanic” of PC’s I have found, as long as it is not being used as a crossover cable, that it really does not matter what order the wires are in. You just need to make sure that the color order is the same on both ends. If you have access to the other end of the wire, note the order of the wires and when you put the new connector on, make sure it is in the same order. Of course, this might confuse anyone else that might come along if they are not in the standard order but all these are, are just copper wires.

To do a quailty job you really need a special crimping tool for RJ45s. Here’s an example: for $20.

Any half-ass crimp job with a screwdriver, etc., will result in an unreliable and intermittant (read “slow”) connection.

As to which wire goes where, the other posterss have the key. Make the two ends match and you’re in business. Make sure you’re looking at both connectors from the same orientation, otherwise you’ll get all the wires reversed and that won’t work at all.

Thanks to all of you. We found that the RJ-45s don’t fit into our Ethernet hub :dubious:
Any ideas why not? Shouldn’t all CAT % cables have RJ-45 ends?

That would be CAT 5

previewTHEN post. preview then post

If it’s an ethernet hub that doesn’t use Fiber it should have an RJ45 connector is the connector on the hub bigger than the RJ-45 or a different dhape. If you post the model # of the hub that would help

Well, one can use cat5 for any number of applications, some of which will require different types of termination. But to my knowledge, when speaking of computer networks it’s always and only RJ45.

You’ve got to be more specific than “don’t fit.” Is there no jack? Is the jack a different shape than the plug?

Generally when tab A doesn’t fit into slot B, one of them isn’t what you thought it was. I find it hard to believe that there could be any antique DB-15 or BNC ethernet hubs out there anymore, so the hub must be RJ-45 if it really is an ethernet hub. The other possibility is that somebody put an RJ-11 or some other keyed telco plug onto the wire instead of an RJ-45.

Believe it or not the secret is to remove only a little bit of the outer jacket. When I first started making cables I stripped an inch or two of insulation off in order to have enough free length of wires to poke them into the RJ45 one at a time. It’s a mess and they don’t work very well, connection is weak, ick.

So first of all get a crimper down at Radio Shack, they are cheap, maybe $20.

Then strip about a half inch (that’s all it takes) of insulation off. Per previous posts, line up the wires in the same order as the good end of the jack. It takes a little practice but you’ll be surprised that you can get those short ends of wire in the right order after a few tries. You’ll have to sort of smash the whole set of free ends flat. Then carefully insert the bundle into the connector (pinch tight with your fingers as you snug it into the jack, to keep the wires in order), visually confirm that everything went into the right slot, and crimp.

It’ll take a few tries to get good and if you have stubby fingers like me it’s a bit frustrating at first but you’ll get the hang of it quickly.

I have to disagree with this.

Just because the wires are the same on either end does not mean that it will work. The transmit +/- and receive +/- signals need to be on their own twisted pairs to work as intended. Anything else could result in a cable with a severe length limit, poor performance, or it may not even work at all.

Pins 1&2 should be on one pair, and pins 3&6 should be on another pair. There is more at work here than just providing an unbroken electrical path from one RJ-45 to the other. Build your cables correctly the first time, and you may save yourself massive headaches down the road.

An RJ45 that isn’t crimped properly won’t fit into the hub.

Ok here is what I was talking about.

We will take use four wires for the sake of typing.
Grouped by pair:

1 +
2 -
3 +
4 -

It would not matter what color the wires are.
Let’s use red, red/white, black, and black/white.

You could have it:
1 red
2 red/white

3 black
4 black/white


1 red
2 black

3 red/white
4 black/white

As long as the colors on both ends of the cable in the connector are in the same postion, that would allow the circuit to complete.

odaranIn your second case, you would have a cable with severe bandwidth limitations. Each color/color+white pair is a twisted pair within the outer insulation. Having a signal and its return on a twisted pair is a good thing for noise reduction, bandwidth, etc. Having a signal and a different signal on one twisted pair, and their returns on a different twisted pair is not a good thing. If you’re going to install ethernet, you may as well put the extra 5 seconds of labor into doing it properly and getting the maximum possible bandwidth.

Here’s a link to a page describing the 2 accepted Cat5 ethernet wiring schemes, T568A and T568B.

This is true. I had straight through cables in excess of 25’ that wouldn’t work with fast NICs. I changed them to reflect the pairs on the correct pins and all was cool.

:smack: What I meant to say was

1 red
2 red/white

3 black
4 black/white


1 black
2 black/white

3 red
4 red/white
Ugh that is what I get for posting between calls.

I’ll second this. The goal is to cut the jacket back just far enough so that when the smaller wires are jammed all the way into the RJ45 connector, the part of the connector that gets crimped is crimped onto the jacket, not onto the individual wires. This way the jacket acts as strain relief for the connector.

I also find it handy to arrange the wires all in the right order, then, holding them all sandwiched in a pair of needlenose pliers, cut them all to the exact same length so they’ll all go the same distance into the RJ45 connector. As you slide them in, watch the end wire slide in on the side of the connector and make sure it reaches all the way in the little channel so it’s under the tiny blade that punctures it when you crimp.

I used to hate that task, but after a few hundred, I actually started to enjoy it. My incidence of making cables that don’t work is way down (seemed like it was 50% at first).

I would be damn nigh impossible to do well, IMHO. A crimper does more than just depress the plastic tab to hold the wire. It also depresses each of the 8 thin contacts into the individual wires. Not your average screwdriver patch-up…

That’s still not right, though.

Pin 1 is transmit+, pin 2 is transmit-. They should be on a twisted pair.

Pin 3 is receive+, pin 6 is receive-. They too should be on their own twisted pair.