jklapperich,
As Barry indicated, MTH did, they put it in the DCS TIU to protect all the different engines. Probably why I have never had a spike problem on my layout.
PCRR/Dave
An ideal place for the TVS is in the locomotive, and it would be easy for the manufacturers to provide one.
gunrunnerjohn,
Maybe they should, with both the TIU and individual engines both protected
there should not be any further spike problems.
PCRR/Dave
The manufacturers "should" do a lot of things they don't. 
If you look at the PS-2 5V board you will see a TVS in the circuit near the FWBR. If you look at the PS-2 3V PS board there is a SMD that "may be a TVS". G
They're pretty small, no? However, something is better than nothing. I guess the TVS doesn't help the 5V board very much, they still have a poor reliability reputation.
