Re: TMCC Signal Problem

[Scott A Smiley <sc.smiley@juno.com>]

The dialog is great.

My engine that would not perform on the layout Sat. Ran fine on Craig's
store layout and on my home track.  Probably not an engine problem.

I will not be back in town until Sat. Night so will miss the Sat. run
time.

We can clearly work on improving the ground system to the tracks, both
jumpers between rails and the ground connections under the layout.  I
Also think that we should consider converting another wire to ground.  WE
have added more wattage to the transformers and some time max out the
transformer capacity so we could be having a ground shortage, obviously
not good for TMCC.

I would discount the track interference possibility since we used to run
with out a problem.  

I think that we should replace the plugs, or at least switch the melted
ones from being the primary connectors from the power box.  I did switch
the wires/plugs at the power box with no improvement though.  Changing
the damaged male and Female ends would be smart.

Earth ground is the third prong on all cords.

Sounds like a issue the Board needs to decide on which items we put on
our to do list and budget for. ( after the testing).

Scott





On Mon, 20 Nov 2006 14:19:41 -0600 "Ira Schneider"
<ira_schneider@Iname.com> writes:
> I just spoke to Mike Reagan at Train America Studios (TAS) about our 
> TMCC signal problem.
> 
> He gave me some insight about how the TMCC system works and what 
> kind of things can cause
> TMCC signal problems.  He also gave me some suggestions about how we 
> might be able
> to determine the cause of our signal loss:
> 
> 1. Put a TMCC engine which experiences signal problems on the track. 
>  Hold your hand about
>     an inch over the top of the shell (i.e. above the antenna) and 
> try to run the engine in
>     command mode.  If the engine runs normally, the problem is that 
> the antenna in the engine
>     is too short.  This can be remedied by extending the antenna 
> (i.e. adding a piece of wire
>     to the antenna inside the engine's shell).
> 
> 2. Both outside rails need to be connected to ground.  The TMCC 
> system relies on the fact
>     that the signal is broadcast from both rails and that the two 
> signals reinforce themselves
>     an inch or two above the track (where the antenna is in the TMCC 
> engines).  If the signal
>     is only being broadcast by a single rail, the signal may be too 
> weak when it reaches
>     the antenna.  The obvious solution is to ensure that ALL modules 
> have both rails
>     connected to the common ground and that both ground wires (i.e. 
> in the 4-wire and 6-wire
>     harnesses) are connected together.  We need to inspect all 
> modules which are using
>     K-Line shadow rail and make sure that both outside rails are 
> connected to the ground
>     wire (or or are jumpered together).
> 
> 3. You are going to love this one!  The problem may be that the TMCC 
> signal from one track
>     is interfering with the signal from the adjacent track(s).  
> Since all four tracks are radiating
>     the TMCC signals, and the signal path to any section of track 
> may differ from the path
>     to the adjacent track, the signals may be slightly out of phase.  
> If so, the signals may
>     cancel each other out.  A solution to this problem is to install 
> a ground plane between
>     the adjacent tracks.  (A ground plane is simply a piece of wire 
> (any gauge) connected
>     to earth ground.)  We can test out this theory by temporarily 
> running a wire
>     between two tracks (where we have TMCC signal problems) and 
> connecting the wire
>     to earth ground.  If this fixes the problem, we need to find 
> some way of permanently
>     installing this ground plane on all modules.
> 
> We discussed various theories about what may be causing our problems 
> and he said the
> following are not likely to be causing the problem:
> 
> 1. MTH DCS system.  This system was designed to be operated in 
> parallel with TMCC
>     and should not cause any TMCC signal degradation.
> 
> 2. Metal bridge on track 3.  Rick's bridge is not likely to disrupt 
> the TMCC signal.  If
>     anything, this bridge could be a perfect ground plane if it was 
> connected to earth
>     ground.  It would isolate the TMCC signal on track 3 from tracks 
> 2 and 4.  Of course,
>     it is only a short bridge, so it wouldn't help the overall 
> problem.
> 
> He also said that the TAS TMCC Signal Doubler was actually designed 
> for 2-rail operation.
> It superimposes the TMCC signal on both rails to mimic the 3-rail 
> systems.  He only
> recommends using the Signal Doubler on 3-rail systems if there are 
> large sections of
> the layout where one of the outside rails is insulated to provide 
> train detection.  In this case,
> the Signal Doubler would send the signal along both the outside rail 
> and the center rail,
> again mimicing normal 3-rail operation.  In our case, he doesn't 
> think the Signal Doubler
> would help.
> 
> We know that our layout used to operating TMCC engines flawlessly.  
> Over the years, TMCC
> operation has degraded.  In the past few years, we have been using 
> more and more K-Line shadow rail for
> new and refurbished modules.  We have also added the MTH DCS system 
> (which is only
> connected to tracks 2 and 3).  I still suspect that the main problem 
> with the TMCC signal is
> the lack of continuity of the ground signal across the K-Line shadow 
> rail tracks.
> 
> Since we are set up at The Railyard, we can experiment with some of 
> this stuff.  I will bring some wire
> with me on Saturday and we can try out some of his suggestions.  If 
> you are coming to The Railyard
> on Saturday and have a TMCC engine which has been running poorly (or 
> not at all) on our layout,
> please bring it so we have something to test with.
> 
> Thanks.
> 
> 
> Ira
> 
> 
> 
> 
> ------
> TTAT members reflector.
> 
>