TVS installation

Just one required from a pickup to frame ground.  All the pickups should be in parallel.  If you're doing a Lionel steamer with a wireless tether, you'd put one in the tender and the locomotive as there's no electrical connection between the two.

Gunrunner: Can the TVS be applied to either ZW and/or KW transformers and how would that be accomplished. 

Thanks

Sure, you can put them across any transformer.  They'd be placed directly across the track feed, pretend you're trying to short out the transformer output.

I built a breaker/TVS unit for each of my ZW feeds.  I used a small hobby box from radio shack, with terminal lugs, so they can be disconnected/moved if necessary.  Have only had one trip when an engine derailed across the track, cheap insurance in my book.  

Thanks for the response but I need to know the best way to install a tvs inside a modern loco with a circuit board.  I have a tvs installed across the all posts  on my ZW but have still managed to fry two circuit boards.  Need to install the tvs within the engine.

Right across the center roller and the wheels.  In many locomotives, that's frame ground, but some actually have a wire from the trucks with the outside rails, it's best to use that and the center roller wire.

Thank You, In other words put the TVS inline between the roller and the frame somewhere.

Well, it's across the line.  You're connecting it like you want to power it from track power.  Center roller on one side and wheels on the other side.

otww posted:

Thanks for the response but I need to know the best way to install a tvs inside a modern loco with a circuit board.  I have a tvs installed across the all posts  on my ZW but have still managed to fry two circuit boards.  Need to install the tvs within the engine.

You might want to consider something like the PSX-AC if you have already lost 2 boards with TVS' installed.

My most recent problem involves a Williams GP-38.  The rear pickup has become non functional, as its not picking up any power.  The pickup is connected by a red and black wire and two others to a plug which fits into a socket on the circuit or reverse board.  I don't recall a specific instance of a short but I assume one occured and screwed up the board.  If a tvs had been installed between the red and black wire from the pickup, would that have helped.  Most of my more modern locos son't seem to have an easy way to connect a tvs from the center rail pickup roller to the frame other than maybe through  a light socket clip. All connections seem to go through a plug-in socket on the circuit board. 

The TVS ONLY protects against high voltage spikes, what you're describing is probably a derailment that connected one roller to an outside rail.  This can cook the trace on the Williams board between the two pickup connections.

I think you  are exactly right so how do I protect against that type of spike? I think all my problems have been caused by derailments.  Guess I should stick with post war stuff and forget about any of these more modern engine  which  are just an expensive problem waiting to happen.