Lionel Legacy Base Causing DCS Signal Problems - Resolved -

Just curious but have you test to see if the Legacy base works without the DCS on? I think you want to ensure that the Legacy base is working properly before going through any additional steps.

@Madockawando posted:

Just curious but have you test to see if the Legacy base works without the DCS on? I think you want to ensure that the Legacy base is working properly before going through any additional steps.

I haven't yet tested only the Legacy system by itself (I will try to do that tonight), but a couple months ago I was testing both DCS and Legacy together and the TMCC engines I have were running properly as far as I know.  If I remember correctly I was running both TMCC and MTH engines on the same section of track.  I don't have any Legacy engines to test, just TMCC.  Thanks.

Michael

I think you can use your TMCC engines to test to see if the Legacy base is working properly. My suggestion is to establish a baseline to ensure that both the DCS and legacy systems will work by themselves. If they do, then you can more to the next step and evaluate your layout to see how the interaction between the two may be causing interference.

We have the same issue at my club. Legacy/TMCC work perfectly separate but the legacy base kills DCSA Signal when powered up.

I have read of a few instances of this and it always seemed like the cause and the solution were usually different.

It would be great if we could get a complete list of all of the different causes that were found and what the individual solutions were.

I think my first step, based on what you've done so far, would be to borrow another Legacy command base and see if that makes a difference.  I have a 12 x 24 layout wired similarly to yours, and the Legacy system doesn't impact anything about the DCS.  However, we have seen this at Harry's house, and after rewiring for star connections instead of the big bus that was originally done it seems to be resolved.  I'm guessing that how the track is wired is probably a key factor.

The DCS Companion (3rd Ed.) lists various sources of low signal issues (including Legacy/TMCC) at pages 156-158, plus failure to follow initial wiring recommendations; like star wiring, separate blocks, etc.

Seems like that might make a good checklist to start eliminating potential sources, one-by-one.

Thank you everybody for the input so far!

I do have Barry's books and I believe I have followed the wiring principles from there.  My layout is star wired with isolated blocks using 14 Ga wire.  I followed his setup for adding Legacy/TMCC to DCS.  The only thing I didn't do was put an 18 volt light bulb like he suggested, but with just DCS I had a perfect 10 signal so I didn't think it was necessary.

Right now for testing purposes I only have 1 block of 1 loop hooked up.

Here is a link to my layout build with some pictures of my wiring for more clarification.

https://ogrforum.ogaugerr.com/...suggestions-critique

GunrunnerJohn:  That is a good suggestion about switching Legacy bases to see if the problem resides in the base itself.

Also for clarification, the issue is occuring with no Lionel engines on the track, only MTH engines.

Thanks.

Michael

Before you go through the trouble of switching Legacy bases, have you tested the Legacy base that you have now by itself?

Madockawando:  No, not yet, but that is the first thing I will do before anything else, hopefully tonight if I have time. 

Michael

Good luck! Hopefully that test will help you bracket the problem.

Since the Legacy Base sends only the 455 KHz ("TrackLink" per Lionel's diagrams) signal to the track, there should be no conflict between the signals.  My club operates both systems with no problems other than initially adding an engine which requires a separate test track.

If, however, the Legacy Base is outputting RF outside of the 455KHz signal, perhaps a filter could clean up the output.  (I'll leave the filter spec. to the EEs on this forum).

Tracker,

If the Legacy Base is transmitting RF other than 455kHz then it's defective.  No need for filters.  It needs to be replaced.

M.H.M.

@Tracker John posted:

Since the Legacy Base sends only the 455 KHz ("TrackLink" per Lionel's diagrams) signal to the track, there should be no conflict between the signals.  My club operates both systems with no problems other than initially adding an engine which requires a separate test track.

Actually, it's been well demonstrated that the DCS and TMCC signals spectrum's can collide.  A guy smarter than I am did a lot of research on the issue.

Correlator Noise floor inflation by Legacy Signal Interfering with DCS

Ahah!  I missed Adrian's discussion when it was posted.

I hate my voice on this but maybe it will help here?

That's an interesting observation Joe.  That looks like the old TMCC base brick, is that what you're using?

Thank you again for all the info and input.  I had no idea this was such a widespread problem amd so much effort has been put into trying to diagnose and solve it.  Everything that has been shown here as well as on the other threads is exactly what I'm experiencing as well.  It is amazing that some people have both dcs and tmcc/legacy working flawlessly together and others of us have issues.  The million dollar question is what is the common variable or variables that either causes it to work or not. 

Has anyone tried putting the legacy base in a seperate room from the layout and running a long "one wire" cable back to the layout?  Or is there anything to do with the position of the legacy base (mounted vertically or horizontally etc) that affects the signal.

I didn't do any testing tonight. 

Very interesting discussion.  Hopefully we can land on something here that will help others with this issue.  Thanks again!

Michael

@gunrunnerjohn posted:

That's an interesting observation Joe.  That looks like the old TMCC base brick, is that what you're using?

yes

Although electrically challenged, it seems to me that the fundamental issue in these cases is that the DCS signal strength is being trampled upon by the Legacy/TMCC signal and this can be caused by a number of factors, including incorrect set-up of the DCS system, such as failure to use star wiring, block creation, etc.

If that is the given, once all the basic DCS set-up parameters have been eliminated as a possible cause, the solution would be to either increase the DCS signal strength (a "DCS buffer") or decrease the Legacy/TMCC signal. Since no one makes a DCS buffer that I know of, that leaves finding a way to decrease the Legacy/TMCC signal strength as a potential solution.

As the OP pointed out, one possible way to do that would be to increase the length that the "one wire" has to travel from the command base to connect to the track. However, I wouldn't do that by moving the command base to another room because that could potentially create over-the-air signal issues with the remote. You could add a signal boosting antenna to the base, but I think a better way would be to make a new, very long "one wire" and run it out of the room and then back (maybe 50' or so ?) before connecting to the track.   

Another way might be to attach the "one wire" to the input side of the TIU (I know, I know) rather than the output side, with the potential that the TIU's electronics would degrade the Legacy/TMCC signal enough to not stomp all over the DCS signal and still be strong enough to run  Legacy/TMCC equipment.

Just my random thoughts and maybe worth a shot.