ᐅ How to identify faults in a cable within a LAN?

Created on: 25 Nov 2020 06:05
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bauherr201615
Hello, I have installed 5 Cat7 network cables in the house. They all start at a patch panel and then go to the network outlets.

The problem now is that one of them doesn't work. I have already replaced the outlet once and connected it to a different port on the patch panel. Each time, the tester shows that channel 8 is not working.

How can I identify the cause here?
11ant25 Nov 2020 16:37
Tarnari schrieb:

Maybe the non-working socket is wired according to the B standard, while the rest follow the A standard, or vice versa?
That would affect the whole pair, so if it’s pin 8, then also pin 7.
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guckuck2
25 Nov 2020 18:55
11ant schrieb:

Are you sure that a router will fall back to 100 Mbit if one conductor is broken?


Usually yes, unless a specific transmission mode has been fixed.
Tarnari schrieb:

Maybe the non-working socket is wired according to the B standard, while the rest follow A, or vice versa?


But the tester will also indicate that. Nowadays, crossed pairs are automatically corrected as well (no need for crossover cables anymore ;-)).
Tarnari25 Nov 2020 19:42
guckuck2 schrieb:

Normally yes, unless a specific transmission mode has been fixed.



The tester will also indicate that. Crossed pairs are nowadays automatically corrected as well (no need for crossover cables anymore ;-))
Yes, that should be the case. Although I was wondering what happens if only a CAT cable is initially connected to the device at such a socket... since the outlet itself can’t perform negotiation.
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WingVII
25 Nov 2020 21:06
Measure the conductor against the shield. You probably have an insulation fault (if continuity is present).
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knalltüte
29 Nov 2020 18:44
11ant schrieb:

That would affect the entire pair, so with 8 it also applies to 7.
Wire pair 7/8 (brown/white + brown) is the same for TIA 568 A and TIA 568 B, so it doesn’t matter here.
My advice: borrow a Fluke DSP or similar tester, measure, and locate faults with an accuracy of a few centimeters.
I could help out if you are nearby (NRW / Münsterland).