The tech 6 requires that the locomotive be set to the original address of 3. It has it's own way of addressing DCC locos that isn't the same as a full DCC control system. Works great for what it does but does have limited functionality. It also helps to buy the remote keypad for it.
Read the instruction manual on the link below:
https://www.modelrectifier.com/product-p/0001200.htm
If you add the keypad you'll spend the same a what you'd pay for NCE Power Cab starter system with full DCC functionality. A DPDT toggle switch that allows feed from either DCC or your old DC transformer will do the same thing as a Tech 6.
