How to wire a network cable crystal connector? The T568B cable is enough; I scrapped six to understand the difference between four and eight cores

we moved last year, the internet cable left by the landlord was forcibly pulled by a previous tenant, and the crystal connector snapped, sometimes connecting. I thought I'd just buy a finished thread myself, but the hole for going through the wall was too small to pull out, so I had to cut off the old end and press it in again. With just this one end, I had to scrap six to sort it out—not because it was difficult, but because no one told me which type of wiring to carry or what the difference between four and eight cores was. This article covers tools, thread sequences, techniques, and troubleshooting all in one place. After reading, you're most likely to master it in one go.

prepare all the tools first: three items for fifty yuan

need three things for self-crimping: crimp pliers, crystal heads, and wire gauge. For crimping pliers, just buy the 25-yuan type with free shipping. It can cut and strip threads, has a crimping groove, and will never break for home use. Crystal heads sold individually, 0.3 yuan each, just buy a hundred packs directly, since they'll be scrapped anyway. The line tester costs fifteen yuan, two boxes and one wire. Plug it in, and the lights turn on one by one—it's connected. Don't skimp on this money—without it, you'll just have to guess after you get the cut.

there's a pitfall when buying a connector: cable connector is RJ45, with eight cables and eight slots; The telephone line is RJ11, with only six slots, which is a bit narrower than RJ45 and . When searching, make sure to check carefully and don't buy a phone headstock. The RJ45 crystal connector contacts are gold-plated; there are cheaper versions, but the feel isn't much different. The real difference is in the pressing—better presses are thicker, and when pressed, the thread is firmly gripped. That's the difference between industrial gear costing two or three yuan and those at 30 yuan. For home use, 300 yuan is enough.

line testers have not only 1 to 8 digital lights, but some also have a GND light, which indicates the shielding layer. Only shielded crystal heads with shielded wires will light up. For household non-shielded wires, it's normal for them not to light up—don't think the machine is broken.

only carry the T568B for the cable sequence, don't be greedy

research, you'll see two types of wire sequences: T568A and T568B. The online comparison tables are neatly listed, which is quite overwhelming to look at. My advice: only carry the T568B for home use, and always use it only for .

T568B order: metal contacts facing up, crystal head clips facing down, counting from left to right. The eight wires are: orange-white, orange, green-white, blue, blue-white, green, brown-white, brown-white. No need to memorize the formula; press it three times and your hand will have muscle memory. My own way of noting it is to think of two pairs of colors at both ends: the Orange family and their family line up for the first two, the Green family for third and sixth, the Lan family for the middle five, and the Brown family to finish the last—the two members of the Green family are separated by the Lan family, which is the easiest place for 568B to make mistakes, focusing on the third and sixth positions.

When should I use the T568A? The standard says government projects use A, but in real life, you almost never encounter it. In the early days, there was also the custom of through and crossover lines—both ends were through lines, with one end A and the other end B being cross lines, used for old switches. All current devices support automatic flipping, and the straight cable is all you can do—this trick can be discarded altogether. The only thing to ensure is that both ends of a wire must be in the same order—one end B, one end A—and the line gauge will light up as usual, but speed negotiations can cause trouble. This is what I learned from the sixth end of the scrap press.

every eight steps, one line is pressed down, with only two slow spots

process breaks down into eight steps. Let's start with the whole one, then the two steps where I messed up.

Among the eight

steps, the most likely to go wrong is step 4 trimming and step 5 sending wire. At this step, all eight wires must be cut flat a single . If the lengths are uneven, the shorter ones won't reach the bottom of the groove, and if the contacts press down, they won't reach the copper wires, causing the wire gauge's light to turn off. How long to keep it also matters: if it's too long, the outer skin won't press into the crystal head's bite teeth, so the wire is supported by eight bare copper wires, which can be used for months and then have poor contact; Too short copper wire simply cannot reach the contacts. About 1.4 centimeters, which is exactly the length of an adult's fingernail.

I wasted three ends in the thread delivery step. All eight wires must enter eight slots at once. If any one misses, it gets stuck at the slot at the opening. It looks like it's going in, but the copper wire doesn't touch the contacts. The standard for judgment is to glance at the window at the rear of the crystal head, eight white wires must reach the top of the window to show a slight . If one strand isn't in place, don't press it. Just pull out the thread and recut it neatly before reinserting. Forcing it down is just sacrificing a single end for nothing.

the four-core and eight-core accounts, I paid tuition with 300 Mbps broadband

This is the section I most want to write. In the first year, I just wanted to save the thread and only connected four wires—the four wires at positions 1, 2, 3, and 6 (orange-white, orange, green-white, green). Many old tutorials online teach this way, saying it works well. It really works. The line detector lights up at 1, 2, 3, and 6 are on, and the network does work. It wasn't until I upgraded broadband from 100 Mbps to 300 Mbps, and my desktop speed test was just over 93 Mbps, I suspected the optical modem was plugged into the wrong port. According to classification, the optical modem is divided into gigabit and hundred-megabit ports and after checking the approach, the port was correct—once the network cable was replaced with a finished 8-core cable, it immediately reached 340 Mbps.

principle in short: 100Mbps uses only four 1236 wires for transmission, while all eight gigabit wires need to be . A four-core cable is sufficient for 100Mbps broadband, but your broadband, optical modem, and computer network card are all gigabit, so when stuck on the cable, you only have 100Mbps left. Plus, it won't show errors—it's quietly slow, which can be quite tricky. So after 2020, when crossing the line, don't hesitate—get all eight cores.

has an even more hidden pitfall: connecting a four-core cable to a POE camera can cause problems. Many POE power supplies use the 4578 with four idle wires. If you cut four cores and the camera cuts off, it won't light up. After a long check, the power supply device is fine, but the problem is the network cable missing four pins. If you have surveillance cameras at home, just lay the cables and stick to the core properly—it's all settled.

the line gauge does not light up after pressing or the light sequence is confused, check the five methods in order

if the thread doesn't pass after the stamping, don't rush to cut the hair. Follow this order to check, and half of the issues don't need to be re-stamped:

First, check the order of lanterns. On the main side of the line gauge, lights up from 1 to 8 in sequence; if the secondary terminal also lights up from 1 to 8, it will turn on. If a light on the secondary unit doesn't work, remember the light number—if 3 doesn't light up, the third wire (green and white) isn't pressed. Check the length and position of the wire by pulling it out. Usually, cutting it all and resending it will fix it.

Second, check both ends. The lights jump randomly, so I suspected the cable detector and connector were not properly connected, especially the 30-cent connector—the latch was soft, and when I pushed the cable detector all the way in, I heard a click.

Third check line sequence. The lights are on, but the order doesn't match at all. Eighty percent of the T568B ends are lined up with other ends. I opened the case and checked the color order.

the fourth line check itself. Most threads that develop problems after some time are due to oxidation of the crystal head or loose pressure on the lens. Black contacts or green spots are the problem. Cut off the heavy pressure, don't scrape it off before reusing it—treat the symptoms.

Fifth check: Is the line caught by the door? If you have a exposed wire running through a door frame, the door will clamp it and break one or two cores. Whenever the wire tester doesn't light up, that's exactly where it breaks. In this case, you have to replace the entire wire—heavy pressure won't save it. When applying long-distance wire nails to walls, don't use staples; use wire clips. Once the nail bites into the outer shell, the core is close to breaking.

when it's worth buying yourself, and when exactly is it worth buying ready-made

to be fair, finished patch cords cost a little over ten yuan each. The machine presses them more neatly than the hand, so if you can use finished products, use them. Wire-wrapping yourself is only worth it in three situations: first, the cable must pass through walls or pipes; if the head can't get through, it must be pressed backward—this applies to wires embedded in renovations; Second, long-distance non-standard lengths, for example, 35 meters from the computer room to the living room, and the finished product line may not have a suitable length; Third, emergency relief: if the line breaks at midnight, all shops close. Later, I helped a friend reinstall the weak current box. After installing over twenty connectors, it was already very smooth. the network cable planning the points mentioned in that article, I ended up relying entirely on manual crimping to finish the ends.

Here's a sequence for those who want to get started: first spend fifty yuan to buy all the tools, use leftover corner lines from renovation to practice three to five angles, practice until the line gauge lights up all at once, then touch the proper line. The work of threading the cloth pipe requires threading first and pressing later, leaving half a meter of clearance at both ends before cutting the scissors. If your home has a bunch of switches and routers, not having enough ports is a different matter. Refer to what I wrote about how to choose and connect a home switch. First, sort out the topology before making the cables, so you don't end up with a bunch of cables and find the plugs in the wrong places.

just remember three sentences: only carry the T568B in the wiring sequence, and both ends must be consistent; All eight cores connected, four cores are a thing of the past; Cut neatly and finish all the way, pressing forward to look at the window. If you follow these three steps, your first time crossing the line will most likely succeed.