Terminate one cable correctly, one wrongly, and record what each proves

short · 60 min · Objective 2.3

Task

Make a working patch lead and a deliberately faulty one, so that the tester results in the next lab have something real behind them. Making one wrongly on purpose teaches more than making ten correctly.

Steps

  1. Record the pin order you are working to in lab/cable/scheme.csv with header pin,colour for all eight positions, and name the standard in lab/cable/standard.txt.
  2. Terminate one cable correctly at both ends. Record the finished length and the untwist length at each end in lab/cable/good.csv with header end,untwist_mm,jacket_in_plug.
  3. Terminate a second cable with a deliberate fault of your choosing -- one conductor short of the end, a swapped pair, or excessive untwist. Record what you did in lab/cable/fault.txt and seal it until the tester lab.
  4. Write lab/cable/predict.md stating what a wire-map tester will show for each cable, and what it will NOT show.
  5. WHERE NO PARTS ARE AVAILABLE: write lab/cable/fallback.md recording that fact, and complete the scheme, prediction and a written description of both terminations instead.

Verify

awk -F, 'NR>1 && NF>=2 {n++} END {print n" pin(s) recorded"}' lab/cable/scheme.csv
grep -Eic 't568a|t568b' lab/cable/standard.txt
test -s lab/cable/fault.txt && echo "planted fault recorded"
grep -Eic 'split|untwist|crosstalk|attenuation|length' lab/cable/predict.md
ls lab/cable/good.csv lab/cable/fallback.md 2>/dev/null | wc -l

Eight pins recorded, a named standard, the planted fault written down, a prediction that names something the tester cannot see, and either a real termination record or a documented fallback. A prediction that says the tester will find everything has missed the point of the next lab.

Notes

Write the planted fault down before testing. Remembering what you did is not evidence, and the tester lab's value comes from comparing its result against what you know is there.

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