07-31-2011, 09:18 AM
I don't know what locomotives you are using with the transformer, but don't discount the possibility that it is the motor in the loco and not a transformer problem. That is why it is absolutely essential to use an ammeter to find out what the load the locomotive is drawing. Open frame motors will build up carbon on the armature segments. As the carbon builds, you get more and more resistance between the brushes and the armature that the transformer has to overcome before the motor starts to turn. If the carbon build up gets bad enough it can also cause a short between segments in the armature. You can spot the carbon buildup with the shell removed because the armature will be black. Fortunately, it is very easy to clean the armature of an open frame motor like the old Athearn models. Just get a #2 pencil with a new eraser, and remove the shell to get to the motor armature. Block the locomotive so that when power is applied, the wheels slip and the locomotive doesn't move. With the motor running full speed, touch the armature with the eraser and move the eraser back and forth until the armature is shiny brass again. Finally after the armature is shiny, shut off the motor, and take your smallest precision, flat blade screw driver, and clean out the black spaces between the armature segments. Give you wheels a good cleaning and also check the contacts where the power is transferred from the wheels to the frame and from the frame to the motor. Make sure that every connection or transfer point is clean. finally make sure your track is clean and all connections are good.
The old style power packs used a wire wound resistor with a slider on the end of the handle. As the handle was moved the slider moved up the resistor and reduced the amount of resistance. The power pack always put out full voltage to the resistor when plugged in and turned on. The position of the slider on the resistor determined how much resistance would be used to reduce the power out put from 0 volts to full voltage. The point of all of this is that resistance reduces voltage. The voltage reaching you r locomotive will determine it's speed, and also how well the locomotive responds to the throttle inputs.
The old style power packs used a wire wound resistor with a slider on the end of the handle. As the handle was moved the slider moved up the resistor and reduced the amount of resistance. The power pack always put out full voltage to the resistor when plugged in and turned on. The position of the slider on the resistor determined how much resistance would be used to reduce the power out put from 0 volts to full voltage. The point of all of this is that resistance reduces voltage. The voltage reaching you r locomotive will determine it's speed, and also how well the locomotive responds to the throttle inputs.