While preparing for my open house in early November, I was experiencing some trouble bringing the system back online following a short. I would clear the short, but the Digitrax system would continue to report a short mode.
I finally found that if I took my A-A lashup of Walthers E8 diesels and tilted them off the rails for a moment, the system would return to service. I figured it was something amiss with the E8's.
During my open house, Jeff Warner, a local and co-moderator of the Digitrax Yahoo Group, indicated that the cause is an excessive power draw by sound decoders that is falsely interpreted as a short. Jeff recommended the PowerShield X, or PSX for short, from DCC Specialties.
First and foremost, the PSX is a short circuit detector. At first glance, that seems redundant, since the Digitrax command station and boosters have their own short circuit detectors, not to mention the power supplies that are connected to mine. But the PSX goes beyond that.
As the documentation explains, "the PSX specifically addresses the increased inrush loads (currents) which occur due to large capacitors used for sound systems. This load appears as a system short circuit until the capacitors are charged. The logic in the new PSXs determines if the load is a true short or just an inrush overload."
I had three on order the next day -- one for each of my power busses. They are now installed and are performing perfectly!