Dead DS ethernet ports? Post here!

[Jon Stratis]

Originally Posted by Mentor007

Team 2228 lost 3 Ethernet ports on DS stations pre-season. Both DS stations had the grounding modification prior to going dead. The damage occurred in Tethered mode testing with the robot up on blocks I believe. Conveyor systems may be generating ESD. We did look at the box that had two ports fail and found that it appears that for each port the HALO isolation transformer has failed. There did not appear to be any ESD suppression on the design such as Transient Voltage Suppression diodes. Davidcom chip on the other side of the isolation transformer appeared to still be functional. We are working to assure we retain a common ground on both sides of the Ethernet cable with the addition of a wire with 1Mohm resistor tied to grounds on each side. We are also concerned that if damage is occurring on the DS side of the cable, are we damaging the other end? So far this does not appear to be a problem for us, and don't see any indications on Chief Delphi. If the damage is limited to the isolation transformer and the DS unit is not warrantee replaced, the replacement part is readily available for $3. Surface mount repair on the 16 lead part and you might still have a unit useful for non-competition. Tough situation and we continue to encourage FIRST's efforts to identify the cause and share way to avoid failures with teams.

That is some great information. The officials at the competition had a box open and i took a long hard look inside, and know exactly the part you're referring to - it was my best guess as to the source of the problem, although the internet there wasn't working at the time, so i couldn't pull up a data sheet... If they don't replace it under warranty, i'll definitely be opening it us and taking a close look at that chip. It's been quite a while since i've done any surface mount work though...