inline circuit breaker

If you go to the 'search' feature on the top of the forum heading, you can search for 'circuit breaker', there have been tons of discussions with that topic if you want more depth. It also depends what your power source is (you don't say). If you are running a modern transformer, likely it has quick reacting circuit breakers built into it. Older transformers have thermal circuit breakers that are slow as heck, that is the issue.

So basically what you need is a fast blow breaker or fuse in line with the power going to the TIU from your power source (in line meaning literally that, it is put in the lead bringing power from the transformer to the TIU, a lead goes from the breaker to the transformer output, the other lead goes from breaker to TIU power in). Airpax is one of the common fast blow breakers, usually recommend using the lowest value that will run your trains (like 7.5 amps, some use 10), but an auto style 10 or 7.5amp fuse would work as well if the cost of an airpax is too much.

Here is a good thread. I use these in line with 5 amp thermals, and the 10 amp Airpax always trip first in a short. Search for fast acting breakers to find many more.

@bigkid got the jump on me.

Search is your friend.

Many, many, many threads on this topic.  Start with John's suggestion.  It's a good one.

Mike

Just started reading them.  First lesson....do some more searches before your post.   Thanks for the quick responses.

One other off topic suggestion - a faulty port on a TIU can frequently be caused by a simple blown fuse or TVS diode; parts that are readily available.

If you're comfortable taking the cover off the TIU (and possibly having to do a little soldering if it a TVS diode), there are many threads on the Forum with instructions, tips, tricks and pictures of what to look for, how to diagnose it and how to do the repair. Just do more searches on the Forum for subjects like TIU and blown fuse, TVS, etc.