Cat5 Cable Pairs Shifted, 1, 2, 3, 4,

[Aaron5]

I was called upon to check a connectivity problem of a PC, and I always first test the cable drop point to point with my Fluke DSP-2000.

I'm getting a miswired wire map however showing 1 & 2 connecting to 3 & 4, and 3 & 4 connecting to 1 & 2.
See attached illustration.

When I tried to simulate this wire map on my desk with a new patch cable, my wire numbers shift on my display with 6 moving up to the 4th position, and 4 moving below the 6 positions. I was just going to transpose conductors of one end to correct this.

Both ends are connected correctly, patch panel and a RJ45 plug. I suspect this cable is spliced or altered in the long attic trip home.

Any suggestions appreciated.

 

[ttech]

It may be the fluke trying to figure out the pairs based on attenuation and cable lengths. For the most part each pair is a different length due to the number of twists.

If it is a bad or incorrect splice you could get this error.

The TDR feature may show a spike at the point of the splice and you may be able to find it, based of the length for the tester it shows.

 

[Aaron5]

Resolved

I found out that someone had punched down keystone ports as T568B that were connected to a patch panel in T568A format.

Is there no way to edit posts in this forum?