I don't understand what the white cam lead gets hooked up to. Some model steam locomotives are equipped with, or can be equipped with, a cam arrangement which coordinates the sound to the rotation of the drivers creating chuffing. As the wheels turn, a switch opens and closes, operating the chuff sound produced by the sound decoder. The white wire goes from the decoder to a microswitch which is operated by a cam that is mounted on the axle of one of the drivers. In operation, when the white wire senses the DCC track signal, it operates the chuff sound ...
CV133 and CV134 work together to control chuff timing. CV133 and CV134 can be adjusted to create the desired chuff rate in your locomotive, or you can configure your sound decoder with CV133 and CV134 to use an external cam to create chuffing sounds. CV133 Steam Chuff/CAM configurations: CV 133 set to a value between 1-127 determines the driver size in inches. (Default Value = 63) CV134 Steam gear ratio trim CV 134 set to a value of 32=100% ratio. Setting CV133's value from 1-127, puts the sound decoder into 'Autochuff' mode. Autochuff mode tells the decoder to simulate driver ...