With the power cord that Bachman has with its controller (the one going from the controller to the track) how can you tell which one is positive and which is negative? I would like to set up cab control but need to know what is the common ground.
I'm not sure you can. You may want to denote which is forward and which reverse.
Gene
It doesn't matter, just pick one lead to use as the common, and stay consistant between blocks and cabs. A way to check when adding a second power pack (cab)is to use the first and start the train in forward motion. Shut off the block and then touch the leads from the second power pack to the track, if the engine still goes forward note which wire goes to which track and keep things consistant. If the engine goes in reverse switch the wires. You should be ok.
If you really want to know which is positive and which is negative, stick the leads into a fresh slice of potato and wait a couple of minutes. The black deposit forms around the negative lead. Or use a meter and save your potatoes for French fries.
It does not matter what lead is negative, It changes when you reverse the controller. When setting up block control divide your rails into either- outside rail or inside rail or alternativly- north or south rail and make sure the one connection from the controller is only connected to that specific rail.
Dave
Three Stooges
Moe: Only fools are positive
Larry: Are you sure?
Moe: I'm Positive!