Need help with K-Line TMCC/DCS Caboose

That switch allows you to set the smoke unit for conventional transformer (CONV) power OR for the higher/ constant voltage TMCC/DCS environment.

 Setting it to TMCC/DCS prevents the higher voltage from burning up the smoke unit.

The older K Line cabooses ( and other conventional cabooses) that do not have this switch, the smoke units have been known to melt roofs at TMCC/DCS voltage.

Just to add one small suggestion to what Rick has said: If you use the smoke unit, even with the switch in the correct position, monitor it very, very carefully. The smoke units in K-Line cabooses are mounted too close to the plastic and I have heard of them melting the plastic even if they are set correctly. If you're going to use smoke, stop the train every few minutes and feel the temperature around the stack until you are sure it isn't going to overheat. And never, ever let it go dry. I don't think smoking cabooses are worth the trouble, frankly. I have several K-Line cabooses and I keep the smoke units OFF.

So what was different inside electronically on those?  Any one have a picture?  G

I believe the switch just adds a diode in series with track power.

If you like smoking cabooses, but don't want to melt the roof or side, consider a fan driven smoke unit upgrade.  I put the MTH HO smoke unit in a couple of them.  With a small adjustable switching P/S, they have adjustable smoke, and the smoke unit doesn't get nearly as hot as any stock caboose smoker, so no melting.

"With a small adjustable switching P/S..." What is this?

Duh........... Power Supply!!   Getting hungry, brain power is low, lol.

On the famous (or infamous) auction site: 261876960293

This converts the track AC to regulated DC, and you can adjust the voltage to the desired value.  There are a number of different options, you can also use the smaller DC-DC modules and provide a separate bridge rectifier and capacitor for better space utilization if desired.