Appendix C: Examples of UTP Cable Faults
Opens in cable pairs generate errors in both in skew tests and in wire map tests. The following example shows a
Figure C-5. Bad cable: Open.
NOTE: There are two problems shown. The skew (difference in delay between pairs) is much greater than 50 ns. Another problem is that the cable length is only shown as 98 feet. Press details and continue the tests. All will become clear when cable map is displayed. Here is a sample cable map.
Figure C-6. Bad cable: Wire map of open pair.
The sample map clearly shows the problem. There is an open at 98 feet on Pair 78. The skew was so large because the timing pulses travel about 200 feet on Pairs 12, 36, and 45, but only travel 98 feet on Pair 78. As always, retest cable after repairs are made.
Page 77 |
