I just bought a Z-500 controller to use with a bump and go trolley and for fun decided to try it with my MTH SD79ACe engine. The bell and whistle buttons were reversed and I found various posts here that said to just swap the wires between the track and controller. This fixed the problem but I was a little puzzled because I had hooked up the red wires with the red posts on the lockon and the controller, and ditto with black to black. The controller posts don't say which is hot or common but I did read that hot has to go to the center rail, and common goes to the outside rail.
So, I wondered if the engine was reversed until I noticed that the lockon I was using had a black thumbscrew for the long copper piece that connects to the center rail and a red thumbscrew for the short copper piece that connects to the outside rail. Weird. I didn't disassemble it to see what was actually going on inside.
I looked at an extra lockon I had on hand and the one that came with the controller, and both had a red thumbscrew for the center rail connector. So, it looks like the lockon I'm using is somehow reversed but I never noticed because I usually run via the DCS remote or a Lionel RTR engine. I thought with AC it didn't really matter which color wire was hooked up to which color post because of its alternating nature. It looks like the bells and whistles and related features like decoupling enforce a wiring restriction so that those features will work properly?
Obviously, it's not a big deal but I thought I'd post this apparent variation on the reversed bell and whistle problem in case someone else gets one of these lockons. This one came with my RTR set. (The thumbscrews don't come off, so swapping them to fix the post colors isn't possible.)
Tomlinson Run Railroad
. Red is the new black!