this post was submitted on 26 Nov 2023
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What color code is this? (alien.top)
submitted 9 months ago by [email protected] to c/[email protected]
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Found this UTP cable once meant for telephones, want to reuse it for Ethernet. Is there some official translation of this color code to what is common on TP cable for Ethernet?

https://preview.redd.it/9k4h5ca3wn2c1.jpg?width=512&format=pjpg&auto=webp&s=03a7ca4ebdbdf633269d2562b4125eddf816e6a8

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[–] [email protected] 2 points 9 months ago (1 children)

I'm going to go out on a limb here, and say that I can see some affiliated colors here.

On the right, you have Orange and Yellow, but for my color scheme to work, let's call it "light orange". So, Orange/Light Orange.

Then, the navy blue and lighter blue is another pair, and I'm calling it Blue/Light Blue.
Then, Brown and a pinkish tan one, which I deem "light brown." => Brown/Light Brown.
Finally, Grey, and white, which is the lightest shade of grey. => Grey/Light Grey.

I would map the Orange pair to the Orange pair, Blue with Blue, Brown with Brown, and the Greys with Greens. Hopefully, that's how they're paired in the cable, as I cannot see that in the picture, but I can make an educated guess.
I can also see they probably used the blue pairs for pins 4 & 5, the brown for 3 & 6, the orange for 7 & 8, and the grey for 1 & 2. But if you're going to re-crimp, use my color mapping.

Also of note, category rated cables have a set number of twists per inch. Generally speaking, the more TPI, the higher the rating, and the lower the electro-magnetic interference, which means higher throughput.

YOUR CABLE might not have enough twists to even reach 100mbps, please be aware of this.

[–] [email protected] 1 points 9 months ago (1 children)

The pairs are grey/white, blue/pink, brown/purple, orange/yellow.

There is one twist per 1.5 cm.

[–] [email protected] 1 points 9 months ago (2 children)

Well, there goes MY theory, haha!
The twists seem low. But I would try it anyway.

Be sure to use the same colors on each end. Put a TP on pins 1&2, then another on 4&5, another on 3&6, and finally, the last one on 7&8.

If you wanna know why the 3&6 pins are use this way, it has to do with history. Back in the day, when there was only one phone line, the RJ11's 4 pins would use a central technique. The middle pins were the one line. The next line was put around the main line, and used the outside pins. This means lazy manufacturers could get away with just using 2 wires for telephony devices. I've opened up a few in my 49 years of life, and I've seen this!

Then, the RJ14 was introduced with 6 pins. They kept the same scheme, and put the 3rd pair on the outer-outer pins. So the main "line" was on pins 3&4, next was 2&5, third was 1&6.

When the RJ45 came out, someone realized that un-twisting the 4th line to stretch to the outer-outer-outer pins, was taking the category out of spec. So, they compromised and put main line on the inner most pins, 2nd line on the next outer pins, but then put a pair on pins 1&2, and a pair on 7&8, and everyone (that mattered) was happy.

So, that is why we all put a pair on 3&6. Also, no solid color (ring) was put next to a solid color of another pair.

  • Pin 1 - Orange & White
  • Pin 2 - Orange - (r)
  • Pin 3 - Green & White
  • Pin 4 - Blue - (r)
  • Pin 5 - Blue & White
  • Pin 6 - Green - (r)
  • Pin 7 - Brown & White
  • Pin 8 - Brown - (r)

Not sure which is the Ring vs Tip for your cable's twisted pairs, but you can try to assume the darker of the pair is the Ring. (Grey, Blue, Purple, Orange)

So, in your case, I would do something like this:

  • Pin 1 - White
  • Pin 2 - Grey (r)
  • Pin 3 - Brown
  • Pin 4 - Blue - (r)
  • Pin 5 - Pink
  • Pin 6 - Purple - (r)
  • Pin 7 - Yellow
  • Pin 8 - Orange - (r)
[–] [email protected] 1 points 9 months ago

After 30 years I know understand why it goes 1/2, 3/6, 4/5, 7/8. Thank you!

[–] [email protected] 1 points 9 months ago

I think I'll just match colors as far as I can:

1 White

2 Grey

3 Yellow

4 Blue

5 Pink

6 Orange

7 Purple

8 Brown

Then I basically only need to remember that Grey is Green, and otherwise just use the colors as I'm used to.

[–] [email protected] 2 points 9 months ago (2 children)

That cable most likely does not meet specs for Ethernet.

That said, you could try to use it, and it might work (or it might not)

Use whichever pairs you like, but be sure you use the same set at each end of the connection, and that each pair corresponds with where an Ethernet pair should be.

This page has an image that shows which pairs go together:

https://doitforme.solutions/blog/ethernet-wiring-t568a-versus-t568b/

[–] [email protected] 1 points 9 months ago

Now that I know this cable is called PTT-298, I found that apparently lots of people managed to get 1 Gb/s Ethernet working on it.

[–] [email protected] 1 points 9 months ago

Well it is twisted pair. From where the ends are, it most likely is no longer than 8m, so I assume that even with sub-par specs it will just work. It is at a friend's place, and we want to avoid opening up the wall here.

I was just wondering if maybe there is some official color code translation, so I could go with the principle of least surprise.

[–] [email protected] 1 points 9 months ago

If it seems plausible, I'd use it to pull through a real Ethernet cable if it seems like it will move easily

[–] [email protected] 1 points 9 months ago

Apparently an old-style French phone cable. For phone uses, it is:

1 grey

2 transparent/pink

3 white

4 brown

5 blue

6 yellow

7 purple

8 orange

Looks like that pairing is unsuitable for Ethernet, so I'll use something else.