I was working at 3 different sites this week for the same customer, replacing jacks (to comply with new color-coding standard), and relocating some of the data cables to a new CAT5e patch panel. The eventual plan is apparently to abandon the remaining cables. At the first site I had no problems. At the second site, I toned out the cables to be reterminated/relocated and tested (wiremap only) each one before doing any other work to ensure that I wasn't inheriting someone else's problem. All of the cables passed the wiremap test.
After replacing each jack, I tested again, and I got the results I expected midway through changing from a T568A to a T568B wiring scheme. After relocating to the new patch panel, I did a final wiremap test. One cable showed a short between pins 5 & 6. After doing a physical inspection of the new jack, the new panel, and the terminations, I found nothing wrong, but reterminated both ends, moving to a new port on the panel. After doing all this, I got the same results.
Now suspecting my tester (an Intellitone 200) I decided to try a different tester (a Microscanner Pro). I got the same results. Using the Microscanner Pro without a remote, I measured the lengths of each pair, from each end of the link. The results from each end were the same, showing all pairs OPEN, and approximately the same length. So, I decided to try yet another tester (an Ideal Linkmaster Pro XL), which has a pre-test mode, that allows you to test from one end with no remote. In this mode it test for opens (by significant length difference), shorts, and split pairs. From each end, the cable passed the pre-test. However, with a remote on the other end (no matter which end), the results showed a short on pins 5 & 6. I got the same results using 3 different remotes, and tested once with the remotes on one end of the cable, and again with the remotes on the other end of the cable.
Stumped, I called a friend to explain my dilemma, and get some advice. In my state of confusion I accepted his suspicion that I had relocated the wrong cable, and decided to verify that I had in fact relocated the right cable. After realizing that I must have the right cable (it passed the initial test), I tested the cable again, and it passed. I tested it with all three testers, and it passed each time. Relieved to have some positive results, and having no idea how to proceed if the results changed, I got the heck out of there.
Today I had the exact same problem at the third site. Then I noticed that the batteries on my Intellitone 200 were low. AHAH! I thought. I replaced the batteries and retested. Still shorted on 5 & 6. Then I realized that I had just put a new battery in the Microscanner Pro prior to testing at the second site, because the batter in it was dead, so I dismissed the idea that the batteries had anything to do with the problem. After several rounds with the various testers, the problem just as mysteriously as at the other site.
Anybody got any ideas? Or should I just chalk it up to Friday the
13th?