Background: I have two Z4000s with each handle connected to one of the four channels of a Rev L TIU. The variable channels are not set to fixed. Using the latest software version. The two variable channels are hooked up to one transformer and two fixed to the other transformer.
While running MTH Proto 2 and 3 trains on the variable channels, suddenly both trains stopped. The Z4000 was flashing a red light. After troubleshooting and isolating the problem, I found that VAR 1 channel of TIU causes the apparent short. At low voltage of 6 or 7 volts the transformer does not trigger the overload but around 10V the current jumps and red light comes on; this is with nothing connected to the output of VAR 1. The transformer works when not connected to TIU. All other TIU channels work properly as well as the transformer.
Questions: Is this potentially related to some TVS issue I had read about with Rev L TIU? What would cause item to fail suddenly when there were no shorts or derails and was drawing less than 4 amps when it failed? The TIU is probably around 3-years old, so should this go back to MTH for repair or to a service tech?
Thanks in advance for feedback/suggestions.