Friday, 15 February 2013

DTX PLA002s cable hints & tips from

Following our recent hints and tips feature for Fluke DTX users we have been asked to highlight a common issue with the PLA002s permanent link adaptor cables for our rental customers and owners alike so here goes :-

A common question relates to the average life expectancy of the PLA002s permanent link adaptors. In short there is no definitive pre-determined life cycle of a cable although Fluke indicates around 5,000 insertions. However at we have observed cables with good use to over 10,000 but on the flip side we have seen brand new cables damaged within just a few hundred. The main area for concern is the RJ45 tip with the eight gold coated contacts as these take the brunt of the insertion forces so are prone to damage and more often just wear. What happens is either the gold contacts became heavily tarnished and removes the highly conductive gold plating making contact with the RJ45 socket less than ideal and or the raised plastic profiles that separate each of the eight gold contacts becomes worn and damaged leading to cases where the plastic can "lean" to one side which makes good mating contact almost impossible. This usually happens to either pin1 or pair 1 or pin 8 or pair 4.

The Black sprung latch on top of the RJ45 housing also takes it's fair share of wear and often "rounds" the top edge and loses its firm spring action resulting in a less the positive seating in the RJ45 socket and often the "click" you use to hear when mated has no all but gone.

The remedy is simple but often not readily achievable in the field which is when and where most have the first indications of a fault with the tip. A simple plug replacement part is available DTX-PRP  and comes with a new PCB 8 way tip, black sprung RJ45 latch and retaining screw. Fit these and your PLA002s will be as good as new. In an effort to reduce this issue with our rental fleet each cable and tip is inspected visually and the self test and set reference function is the first line of defence but unfortunately not definitive as the very next field test could be the one where the tips decide enough is enough.

You can see the current autotest count of each PLA002s and channel adaptor by entering the special functions sections > Version. This will indicate the insertions of the cable or adaptor however a not of caution in that once you replace the DTX-PRP tip the autotest count will not reset so you need to keep a note of the autotest count when you changed the tip.

Another common source of failure is the retaining strain relief boots at both ends tend to became damaged and break after a period of time leading to strain being put on the pairs within either end causing a solder joint failure or such like which is almost impossible to detect or indeed repair. We have tried to eliminate this issue by strengthening each end with heatstrink and find this works well.

In summary keep an eye on your autotest count, visually inspect your RJ45 tips and strain relif boots at regular intervals and make sure you perform the self test and set reference at least once a day, all of which will help to reduce down time. We would also suggest the owners invest in spare DTX-PRP sets ready for when the need arises and our customers can be sure we always have a good stock should the need arise.

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