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.

Actually, the wavelength of the 455khz is over 2000 feet, and putting a long wire on it won't accomplish a thing.  If you really want to reduce the signal strength of the TMCC signal, a properly sized load resistor divider would be the way to go.  In order to know what you were doing, you'd really want to 'scope the signal.  Since the old TMCC BASE1 had a much lower amplitude signal, you could probably get away with chopping the Legacy base signal to about half it's amplitude.

Bad idea sending the TMCC signal through the TIU, that doesn't accomplish what you desire.

@greg773 posted:

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, too, would like to see this.   In saying that, I run Legacy and DCS on my layout, and have not encountered the issue being discussed in this thread.   I would like to be able to preempt possibly issues if ever helping setup a club or show layout.

Well, getting a "complete" list of all the causes is most likely the impossible dream!  By your own admission, there are varied causes, and I'm sure we haven't actually properly identified the root cause of many of the interference issues.  For instance, Joe posted a unique issue that I had never heard of before!  The TMCC being a separate layout and not connected to the tracks with DCS is a new one, I had never heard of that issue before!

A perfectly fine Legacy/TMCC zapping DCS when it’s turned on? Are we sure it isn’t a feature?

Just kidding!!! 😉

Just good engineering I would think!

I wonder if it's VSWR related.  Like once you get close to an even division of the wavelength of TMCC,  you have yourself an impedance matched load that is super effective at radiating the signal.

Remember, the wavelength of the TMCC signal is over 2000 feet.  I have difficulty believing this is the root of the problem.

Did you or Dale scope the TMCC or Legacy signal as a prelude to building the booster ?

'scoped it many times.  I'm sure I must have posted some 'scope pictures here at some point.  The TMCC command base (BASE1) has about a 3V P-P signal, the Legacy base has about a 5V P-P signal.  Unless you have a large or problematic layout, you could cut down the amplitude of the Legacy signal to about half and see how that works out.  I have no idea if it would make a difference in the DCS interference, but it might.

Could the DCS signal interference be caused by the ~2.4GHz wireless signal the Cab 2 and 990 base use to communicate.  Would it be worth trying different Channels on the Legacy system?

Legacy V1.6 manual p.78 lists the 9 different channel options from 2404.0MHz, 2412.2MHz, 2420.4MHz, ..... up to 2480.0MHz.

Really difficult for me to believe the low power 2.4ghz signal is affecting the much lower impedance 3.27mhz signal on the tracks.  I'm not saying it's impossible, just that it would be way down the list of things I'd be looking at.

Isn't the issue with the DCS wireless remote receiving low signal strength as soon as the Legacy system powers up?  That's why I'm wondering about the possibility of heterodyning among all the signals being transmitted, interfereing with a clear DCS wireless signal.  It seems like trying a different Legacy channel might be worth trying as it's easy to do and check to see if it makes a difference.

I've experienced similar issues in the wireless audio realm where multiple transceivers from different manufacturers cause interference with each other in close proximity.

The issues being discussed here have nothing to do with the communication between the remote and the command base or TIU.  We're talking about the DCS track signal getting stepped on by the TMCC track signal.

If you are having remote to TIU/BASE communication issues then changing the channel is a very good idea.

Just wondering if, based on the 3V P-P TMCC signal and the Legacy 5V P-P signal, it's possible to calculate what size resistor you would need to cut the signal, say in half, and how you would integrate the resistor into the system.

Would it be as simple as just splicing it into the "one wire" ?

You can start with a pair of 300 ohm resistors, one in series with the lead and the second one at the track connection to the earth ground connection.  It's a simple voltage divider.  I do something similar on my TMCC test set to attenuate the signal for testing if boards can detect a weak TMCC signal.

@gunrunnerjohn posted:

The issues being discussed here have nothing to do with the communication between the remote and the command base or TIU.  We're talking about the DCS track signal getting stepped on by the TMCC track signal.

Are we sure about that?  Could it be that the 900MHz signal to the TIU is being corrupted somehow and then passed onto the track in that corrupted state?  I thought I read that the logical signaling at the 900MHz carrier is the same as that on the rails, just that it's modulated differently.  If OTA signal corruption hasn't been ruled out, it should probably be run to ground (no pun intended).  However, if the TIU first validates the contents of the command and then rebroadcasts it then this is less likely to be the case.

I'll second @SteveH comparison to wireless microphones.  Once you have several transmitters at play, you have to look at the intermodulation distortion that can occur between two frequencies - far apart as they may be - and how that can affect other signals.  For instance, the IMD products from the 455kHz signal and the 3.27MHz signal could cause something else entirely to be radiated or the combination of 455+2.4GHz - or all three.  Heck - it could be related to the interplay of the those signals with other signals present at the location - TV channels, mobile phones, WiFi, etc.

The wireless microphone manufacturers have created software applications that take into account local broadcast stations, and all of the wireless mics in use in a given location and other TV band devices registered in that geographic location to calculate the best channels to put the wireless microphones on.  I'm not saying that is required here - but I think it's certainly worth a look as to whether or not the corruption happens at RF stage - or as @Adrian! indicated it truly is caused by the increased noise floor and the inability of the DCS decoder to pull the signal out correctly.

I don't know about "we", but I'm sure that the remote to base/TIU communication is not the root of the issue of TMCC affecting the DCS track signal.  You're free to explore that rat-hole if you like.   The relative signal strengths and impedance of the two different signals is vast.

You are also forgetting that the remote communications goes through a processor and is error checked before it's processed before it's turned into the track commands.  I don't know where you read that the remote to TIU communications is exactly the same format at the track signals, but I can't even imagine that being the case.

@gunrunnerjohn posted:

You can start with a pair of 300 ohm resistors, one in series with the lead and the second one at the track connection to the earth ground connection.  It's a simple voltage divider.  I do something similar on my TMCC test set to attenuate the signal for testing if boards can detect a weak TMCC signal.

Perhaps the OP will try this and report back.

@gunrunnerjohn posted:

The issues being discussed here have nothing to do with the communication between the remote and the command base or TIU.  We're talking about the DCS track signal getting stepped on by the TMCC track signal.

If you are having remote to TIU/BASE communication issues then changing the channel is a very good idea.

Please forgive my unfamiliarity with the DCS system.  John, between which devices is the DCS signal strength measured and then displayed on the remote?

In my situation I am using the WIU and the DCS app on my phone so even if signals between the remote and tiu could be an issue it wouldn't be in my case.

I have been busy and haven't been able to get to the layout at all this week.  When I have some time I will try to do some testing and report anything I find.

Just throwing this out as a question.  Is there anything a particular type of track system could be doing to amplify the legacy signal?  I am using gargraves phantom track and ross switches.

Michael

@gunrunnerjohn posted:

Well, getting a "complete" list of all the causes is most likely the impossible dream!  By your own admission, there are varied causes, and I'm sure we haven't actually properly identified the root cause of many of the interference issues.  For instance, Joe posted a unique issue that I had never heard of before!  The TMCC being a separate layout and not connected to the tracks with DCS is a new one, I had never heard of that issue before!

Whoa.... I am very sorry here GRJ.

I traced the issue to a ground wire that connected my upper 3 rail loop to the rest of my two rail. The TMCC signal was connected thru an internal connection on something, that I now forget. I believe it was the Z4000? The 3 rail had a separate TIU so that wasn't it.

It drove me nuts and I only shared the video to show it happens. Nothing else was dragging the signal down. NO TMCC engines on the rails.

Later on when they became available, I had two more PH180 bricks (on order for a year?) so I could separate the Z4000 from my outer O scale 2 rail loop.

Since I got my 2 rail MTH Bigboy, I connected the Z4000 again for higher voltage and power. So I have to remember not to plug in my TMCC base!

Also, my experience is that signal degradation is worse with PS2 engines than PS3 engines.  What is the reason for that?  Thanks for all the input.  I am getting a real education here.

Michael

@Michael Cimba 040217 posted:

In my situation I am using the WIU and the DCS app on my phone so even if signals between the remote and tiu could be an issue it wouldn't be in my case.

OK, well that rules out corruption of the RF signal in this case since if it were, it would likely degrade the WiFi signal to a point where nothing would work.

Just throwing this out as a question.  Is there anything a particular type of track system could be doing to amplify the legacy signal?  I am using gargraves phantom track and ross switches.

As I understand it, in the TMCC/Legacy world the track acts as an antenna.  How much track do you have?  If it was a length of 1000 feet (1/2 wavelength) or multiple thereof, the signal can reflect and "resonate".  Based on your earlier post it sounds like it's doubtful you have that much track.

That said, RF is a tricky business I wouldn't rule out a particular combination of length, materials, and shape to making a more effective antenna out of the track.  However, characterizing that benefit/degradation would require someone with a lot of RF knowledge and likely some RF modeling tools.

@Michael Cimba 040217 posted:

Also, my experience is that signal degradation is worse with PS2 engines than PS3 engines.  What is the reason for that?  Thanks for all the input.  I am getting a real education here.

My guess is that the processor doing the signal extraction (Adrian mentioned it was some sort of convolution, which to me says it's a DSP of some sort) is not as powerful in the PS2 engines as in the PS3 engines - which makes sense.  Typically in that world, if you increase the size of the Fourier transform used you can pull more signal out of the noise at the expense of integration time, i.e. the result might take longer to get.  However if the DSP is faster, you might get it for free in PS3 chipsets.

@SteveH posted:

Please forgive my unfamiliarity with the DCS system.  John, between which devices is the DCS signal strength measured and then displayed on the remote?

The "signal strength" measurement is really a misnomer.  What is actually being checked is sending packets to the locomotive from the TIU and then counting the returned responses.  If you are reading 10's, that means all packets are being responded to and received by the TIU back from the locomotive.  However, that doesn't actually measure the signal strength on the track, it is really just checking if there's enough signal for packets to go back and forth.

@rplst8 posted:

As I understand it, in the TMCC/Legacy world the track acts as an antenna.  How much track do you have?  If it was a length of 1000 feet (1/2 wavelength) or multiple thereof, the signal can reflect and "resonate".  Based on your earlier post it sounds like it's doubtful you have that much track.

That said, RF is a tricky business I wouldn't rule out a particular combination of length, materials, and shape to making a more effective antenna out of the track.  However, characterizing that benefit/degradation would require someone with a lot of RF knowledge and likely some RF modeling tools.

Actually, the track is NOT an antenna in the world of TMCC.  The "antenna" inside the TMCC locomotive is picking up the radiated signal from the earth ground (3rd prong of house wiring), the track side of the signal is connected through the wheels to the electronics directly.  In this regard, the RF propagation model is kind of upside down, but the effect is still the same.

Dale Manquen wrote a significant piece on TMCC Signal Basics, and he clearly explained it much better than I will.  Sadly, his website is no longer up, but I captured that topic here.

Dale's TMCC Signal Basics.pdf

Dale's description is spot on.

@rplst8 posted:

My guess is that the processor doing the signal extraction (Adrian mentioned it was some sort of convolution, which to me says it's a DSP of some sort) is not as powerful in the PS2 engines as in the PS3 engines - which makes sense.  Typically in that world, if you increase the size of the Fourier transform used you can pull more signal out of the noise at the expense of integration time, i.e. the result might take longer to get.  However if the DSP is faster, you might get it for free in PS3 chipsets.

I believe when Barry was around he stated that exact same thing.  I know both the Rev. L and PS/3 chipsets got a much more powerful DSP signal processor for better performance.

@gunrunnerjohn posted:

The "signal strength" measurement is really a misnomer.  What is actually being checked is sending packets to the locomotive from the TIU and then counting the returned responses.  If you are reading 10's, that means all packets are being responded to and received by the TIU back from the locomotive.  However, that doesn't actually measure the signal strength on the track, it is really just checking if there's enough signal for packets to go back and forth.

@rplst8 posted:

Actually, the track is NOT an antenna in the world of TMCC.  The "antenna" inside the TMCC locomotive is picking up the radiated signal from the earth ground (3rd prong of house wiring), the track side of the signal is connected through the wheels to the electronics directly.  In this regard, the RF propagation model is kind of upside down, but the effect is still the same.

Dale Manquen wrote a significant piece on TMCC Signal Basics, and he clearly explained it much better than I will.  Sadly, his website is no longer up, but I captured that topic here.

Dale's TMCC Signal Basics.pdf

Dale's description is spot on.

@rplst8 posted:

I believe when Barry was around he stated that exact same thing.  I know both the Rev. L and PS/3 chipsets got a much more powerful DSP signal processor for better performance.

John, Thank you for taking the time to explain what exactly the DCS "signal strength" means.

On behalf of all of us newer forum members, an even bigger thank you for saving and re-posting Dale Manquen's TMCC Signal Basics article.

I highly recommend that anyone with a TMCC/Legacy system read it.  For the first time, I think I now understand the two different parts of the Legacy 455kHz transmitting antenna:

1st - Connected to the Legacy base's U post is the Outer track rail.  This serves as the antenna base (but as you point out, also a direct conductor to the Loco)

2nd -  the "earth ground" connected from the TMCC/Legacy base back through its wall wart to the House wiring, is essentially the "whip".

From the receiving Loco's perspective, these two electrically opposite Antenna "Poles" (sort-of) both need to be somewhat balanced.  When the signal strength of one Pole overwhelms the other, poor reception by the Loco results.

Sorry for the TMCC tangent here, but this is really good information, and I'm a bit excited to finally understand it, I think.

Now back to DCS...

@SteveH posted:

On behalf of all of us newer forum members, an even bigger thank you for saving and re-posting Dale Manquen's TMCC Signal Basics article.

I highly recommend that anyone with a TMCC/Legacy system read it.  For the first time, I think I now understand the two different parts of the Legacy 455kHz transmitting antenna...

Yes me too.

As to the OPs issue - I still wonder what exactly is at play that could cause the issues he's seen.  Even in the thread that GRJ linked from Adrian, while I think it's understood why TMCC can interfere with DCS in some situations - characterizing exactly what the situation is where one person's dual TMCC/DCS layout won't work - but many many others do, still seems elusive. 

Could the length of the house wiring play a factor?  Also I wonder - in situations where this interference occurs is there a way to determine if the TMCC signal in the air (or the track) is exceptionally strong compared to a "normal" environment.

Yes, thank you GRJ and others for all the invaluable info on how Legacy/TMCC and DCS works.

Would having the Legacy Base plugged into an outlet with a GFCI on the circuit do anything to the signal?

Michael

Well today I finally had some time to do a good amount of testing on the layout.  Tonight I discovered something very interesting.  Up to this point I had connected my test track only to Fixed Output 2 of the TIU.  I started moving the track connection to the different terminal blocks.  First I tried Fixed Output 1.  I got a perfect 10 DCS signal with the Legacy Base plugged in to power and the "one wire" connected to the Fixed Output 1 terminal block common.  I left the "one wire" connected to the Fixed Output 1 terminal block and I moved the track wire to Variable Output 1 and then Variable Output 2.  In both of these cases I got a perfect 10 DCS signal with 1 PS3 engine and 1 PS2 engine powered up on my test track.  So then I setup a second test track.  I moved the 1st track connections back to Fixed Output 1 and I connected the 2nd test track to Variable output 1, leaving the "one wire" connected to the common of the Fixed Output 1 terminal block.  Again I got a perfect 10 DCS signal with 1 PS2 and 1 PS3 engine on test track 1 and 1 PS2 engine on test track 2.

So, at least it appears that the issue is only on Fixed Output 2 of the TIU.  As soon as I unplug the power to the Legacy base the signal on Fixed Output 2 goes to a perfect 10.  I still can't explain what's causing it, but it seems it is only affecting 1 TIU output instead of all 4.

I'll be curious to see your input on this and if this info helps anybody else dealing with this problem.  Thanks.

Michael

Michael,

It could be that you have a weak DCS signal on Fixed Out 2.  If you search the forum, there are reports of this happening with some TIUs that are early Rev. L.  Look for posts from Adrien! (yes with the ! mark).  Gunrunnerjohn also knows a good bit about it and may be the guy to talk too if you need it repaired.

Given that it's only one channel, it's very likely that it's the DCS signal generation and not anything to do directly with Legacy.

@gunrunnerjohn posted:

Given that it's only one channel, it's very likely that it's the DCS signal generation and not anything to do directly with Legacy.

GRJ, Is this a possible issue with the TIU that needs repaired like rplst8 stated, or is it just a matter of trying to improve the signal on that channel with the 18 volt bulb etc.  What was the issue in the TIU that caused signal problems on Fixed Output 2 only and what is the fix?  Is the fact that I get good signal on that channel when the Legacy Base is not plugged in still indicative of a low DCS signal generation.  I will try to test that channel a little more today and see if the signal remains strong without the Legacy Base plugged in or if it fluctuates.  Anything else I should be looking out for?  Thanks.

Michael

A "good signal" is relative.  If you're counting on the track signal test that MTH does reading it on the remote, that's not really a true signal strength test.  All that does is tell you how many DCS packets out of ten can make the round trip to the engine and back.  However, you can have significantly degraded actual signal amplitude on the channel and still get a "perfect" test as far as the MTH measurement is concerned.

The only true test of actual signal strength is to monitor it with a 'scope and see what actual levels exist.

With that being said, if you have read some of the discussions about DCS signal strength and the factors that influence it, including connecting TMCC/Legacy, you'll see that it's far from a simple subject.

The Rev. L TIU DCS output signal drivers are much more susceptible to damage by track transients for some reason.  You'll see several threads on replacing the 74ACT244 driver chips to fix signal output issues.

Thank you GRJ!  I think I can borrow a scope to measure the signals.  Can you point me to the proper procedure for setting up/hooking up the scope to measure the dcs signals and what I should be looking for in the output? Thanks.

In order to measure the signals, you'll need a pure sine wave transformer as you have to add a filter to remove the 60hz power to see only the DCS signal.  Then you need to whack together a little filter to knock out that 60hz signal, and the result will be just the DCS signal.  I set the DCS remote operating mode to SPEED and make sure there's an engine loaded in the remote.  You can then press the STARTUP button whenever you want to see the DCS signal, the SPEED setting prevents the remote from stalling when it doesn't hear from the engine.

Once you get everything hooked up, you should see something like this.  The amplitude of the signal should be at least 10V P-P.  Ignore the overshoot spikes and look at the actual signal, the denser part of the waveforms.

I didn’t read all the posts so maybe it’s been mentioned. I read a long time ago not to run the legacy wire through the TIU. Hook it directly to the track.

@romiller49 posted:

I didn’t read all the posts so maybe it’s been mentioned. I read a long time ago not to run the legacy wire through the TIU. Hook it directly to the track.

Yes, that's correct.  You want to always connect the legacy "one wire" to the output side of the TIU or points beyond (terminal blocks etc), never through the TIU.

@Michael Cimba
You asked:  "Would having the Legacy Base plugged into an outlet with a GFCI on the circuit do anything to the signal?"

No, because only the neutral wire and the phase wire(s) pass thru the detector coil.

@All:  A related safety hint (or 3):

The most sensitive of these trips at 5 milliamps (.005 A).  It is commonly said that if this amount passes thru one's body, it will knock one off a ladder.  More pertinent for the model railroader would be to say that if one is under the layout soldering wires overhead, one will drop the hot iron on one's face.  Remember that lying on a concrete basement floor  is an effective ground for any type of electric tool with exposed metal parts, if its internal insulation fails.  I once had such a drill.  Go with a battery drill.  There is a reason for the popularity of the 20v battery.      ---Frank M.

I did some more testing this evening and it led to more very interesting discoveries and positive solutions I think.  First I just want to thank the LORD for giving me the wisdom to figure this very daunting problem out on my layout and I also want to thank all of you on this forum for all of the expert advice and information that led me to a probable solution.  I hope my experiences will help someone else.

I will preface this by saying I believe the problem was caused by my wiring as GunrunnerJohn had speculated.  There were 2 different aspects of the wiring that came into play here I believe.

From my last post you will remember that I had narrowed the problem down to the Fixed input channel 2 on the TIU.

First, I had my Legacy Base mounted on my control table between my 2 Z4000 transformers.  The power wire for the legacy base as well as the power wire in the split PD9/Serial Cable/Power for the SER 2 ran very close to and in some instances in the same bundle of wires as the cables going from the transformer outputs to the TIU inputs.  The wires coming out of the transformer going to Fixed input 2 were closest to these Legacy power cables.

Second, I had all of my transformer common's hooked together (2 Z4000's and 4 Z1000's) as stated by Barry in his DCS book.  I ran a wire across my control table top from one Z4000 common to the other Z4000 common and this wire passed underneath and very close to all the wires coming out of the Legacy base.  Additionally I had a common wire connected to 1 of the Z4000's from all of the common's on my Z1000's tied together.  This wire passed very close almost touching the wires from the transformer to Fixed Input 2 of the TIU.

Third, I had my WIU on the control table in close proximity to the Legacy Base and the transformers and all the associated wiring as well.  I moved the WIU to under the layout next to the TIU.   

When I removed the Legacy cables from close proximity to the cabling going from the transformer to the TIU and when I removed the wires connecting the transformer common's together the DCS signal improved to consistently getting between 7 to 10 with a PS2 engine where as before it was anywhere from 1 to 6.  Additionally, I then physically moved the Legacy Base to the floor a couple feet away from the control table and made sure all of the Legacy wires weren't close to the transformer to TIU wires.  This gave me a consistent 9 to 10 DCS signal with a PS2 engine on the track connected to Fixed Input 2 and a consistent 10 DCS signal with a PS3 engine.

So, it appears that this combination of wiring routes and component placement was causing my issue.  I can't explain electrically what actually was happening (there are probably many on this forum that can) but I know the changes I made solved my DCS signal issues. 

Now, I will have to figure out the best way to rerun my wires that will yield the same results as what I am getting with everything "loose". 

Thanks again for all the help in solving this issue.  I hope this information will help someone else from having similar problems!

Michael

Fields and waves.  I suspect the legacy rf signal was inducing noise on the closely run wires. You may have heard at some time that it is a good idea to cross wires at 90 degrees, that is why. Sounds like you got the wires separated now.

I really admire how you stuck to this issue and seem to have learned a lot more about debugging your layout.

I recall a situation years ago at a plant where I worked. During some major expansion the electrical contractors ran low voltage control wires in the same tray as the high voltage power lines, everything running parallel. The controls wires were to variable speed pumps and there was no control. Even pros make this mistake.