Continued working on the testing of the modified five wire loco’s.
The F7a short was identified. It had nothing to do with the wiring. This loco has Ernst gearing as well. In this case one of the axle gears is conventional and the other is a special axle gear. On one of the trucks, the conventional gear was cracked, allowing the wheel set shafts to touch causing the short. Replacing it with a good gear eliminated the problem.
The base testing was completed on all four units in this update activity. The fourth unit had rusted wheels binding the brass bearings preventing the motor from driving the wheels. The rusted wheels were replaced with good BB wheels. The base test was also completed on this unit.
For the second test phase, the four units wheels were polished for 20 seconds each. The streamlined performance testing was repeated on two of the units. The others will be tested as time allows.
Toying with idea of trying to link motor health with velocity, drawbar force & current draw for like motors. Still haven’t worked it all out, but it seems to be plausible.