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

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

(OP)
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.

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

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.

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

(OP)
Resolved

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

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