Athearn Blue Box Engines

Short Circuit with Athearn "Blue Box" or older Engines.

This problem does not apply to Athearn "Ready To Roll" or "Genesis" series of engines.


PROBLEM SIGN:  Two Athearn Blue Box engines erratically short out when coupled together.

PROBLEM CONDITIONS:  You are using metal Kadee Couplers in the stock metallic coupler pocket

PROBLEM BACKGROUND:  Athearn Blue Box engines use the metal frame to carry electrical current of one of the track rails via the trucks.  This means the frame is shorted to one of the two rails.  If you connect a 2nd Athearn locomotive which is oriented backwards (back to back) relative to the first Athearn engine, the two frames will have the opposite rail polarity.  The use of metal couplers will allow the two frames to short each other out through the couplers.  The erratic short depends on how tight the coupler are coupled to each other which changes dynamically as the engines roll down the track.  Remember Athearn ships engine with plastic X2F horn hook couplers which prevent the problem from happening.

SOLUTION: Two solutions.

1) OK:  Replace the metal Kadee coupler with Kadee's plastic equivalent coupler.  Eliminates short but that is all it does.

2) Best:  Replace the metal pocket with a Kadee plastic pocket. This will electrically isolate the coupler pocket from the frame of the engine.  Drill and tap the screw to hold the pocket with a metal coupler.  The Kadee pocket will give you better coupler performance than the stock Athearn pocket.  Better centering spring forces and no loose side to side slop.