I am upgrading a friends 2001 Railking Challenger that is Proto 2.0, 5volt to 3volt with a steam upgrade kit. It has mux boards that I want to eliminate. The locomotive mux board is bad and the Proto 2.0, 5volt board is bad. With the steam kit, the smoke heating element and the headlight are grounded with purple wires to the negative side of the two diodes in the plug at the rear of the locomotive. Can the firebox light and the front marker light be grounded the same place as, and along with the headlight and smoke heating element??? My concern is overloading the negative return to the 3volt boards in the tender. I would power the firebox and marker lights from pin 3 of the 12 pin connector on upgrade board in the tender. In the same locomotive, with the 5volt factory system, there is an inline 10K ohm resistor in the orange wire between the 7 pin board connector and the tach reader center connection. I have seen this in at least 2 railking steamers that I own, except mine are 3volt starter set 2-8-0's. Could some one comment on the seemingly limited use of this resistor in the orange tach reader wire??? I had heard of mux boards before, on the forum. Could some one tell me more about them??? Thanks in advance Dad-O
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