Having TMCC / Legacy Signal Problem On Layout, Please Help

The problem arises from signal towers or bridges that use the metal frame as the common ground to power it's lights.  The TMCC signal is also present on the common ground connected to the tracks.  Too much signal - particularly from above an engine - interferes with the engine's ability to receive the signal.  There are many threads on the forum addressing the "TMCC ground plane" and ways to correct poor signal.  In a nutshell, you need to a) use IR sensors, or relays, to ensure the power ground in your trackside accessories and signals is isolated from the track ground that carries the TMCC signal, or b) add a TMCC ground plane wire between the signal and adjacent tracks.  Option (a) always works for me, option (b) sometimes takes considerable experimentation to make it work.

So John, I should attach the crossing lights to a Relay as in diagram Stan gave me where there's a AZATRAX MRAPR-8? Would that fix the problem? Also can I have the Z-4000 commons on the back 10 Volts / 14 Volts be connected to the ZW-L or should I have a seperate Z-4000 just for crossing lights on 14 volts?

Tom, a couple of changes to your relay connections:

1.  The Z4000 accessory voltage uses an internal common ground with track power.  You will have to use a discrete transformer for accessories to provide isolation.  A Z4000 is overkill, a small post-war transformer or wall wart will suffice.

2.  The connection between the accessory ground and the track ground cannot exist (see #1) or the TMCC signal will propagate to all ground circuits.

Tracker John posted:

Tom, a couple of changes to your relay connections:

1.  The Z4000 accessory voltage uses an internal common ground with track power.  You will have to use a discrete transformer for accessories to provide isolation.  A Z4000 is overkill, a small post-war transformer or wall wart will suffice.

2.  The connection between the accessory ground and the track ground cannot exist (see #1) or the TMCC signal will propagate to all ground circuits.

John, this does make sense. What I'll do is, I'll take the wire off for the crossing lights from all the Z-4000's and just apply the common line to one transformer that isn't beeing used much, probably to a separate Lionel Transformer. I'll see if that works.

Actually I've been thinking. I kind of answered the question fast. What I'm meaning is, should I take all the common lines I have connected from the 2 Z-4000's 10 Volts & 14 Volts that go to my one ZW-L and put the crossing lights power onto a Lionel Postwar or other smaller transformer and put the common line from the ZW-L to the common on that smaller Lionel Postwar Transformer or other smaller that gets the power for the Crossing Lights? Would that bring back the signal?

Other thing is, I the bridge area where I'm having the issue, that bridge has a bliking red light and there's a board right underneath that area so that light blinks. I wonder that that would lose the signal also, because I'm not having any other signal loss anywhere else on the layout accept this 4 foot spot and I do have a large layout.

Hey, Tom Jr.,

While you may want to reconsider your power configuration wiring, the issue with the overpass bridge can resolved easily. This is a known and common issue.

For a test, tape a piece of small wire or any that you have under the bridge and run it to the nearest receptacle. Loosen the cover screw and wrap a bare piece around it and then snug it again. Now, run the tmcc/legacy engine under the bridge. it should be ok.

This earth ground  is not the same as the neutral AC, U or common power wire. Tracker John touched on it. That small wire should prevent the signal from the overpass interfering with the track signal below.

Then, find a nice path to route it.

Although electrically not a problem to have a "common" common or U, separate the accessory common from the track common to eliminate any issues with metal accessories causing any tmcc/legacy interference.

Watch this TMCC signal video starting at 15:22 for a few minutes to get the concept and the over/under track solution.

Let us know if that works.

Carl, I like to give thanks to my Dad. He helped on it. And yes the issue was me and him attached a Antenna Wire from the Legacy Antenna on the Base and ran it under the bridge and now the engine runs fine. So thanks to my Dad, it works now. So yes Carl, even though I had it done after you wrote this reply and didn't see it until now, your also right.

Your problem is the signals from the upper track is over lapping the lower one. someone who responded suggest a earth ground. this should solve your problem. It must be attached to the ground of your home wiring.