adding 2 rail tmcc: some success

I think you said the magic word, 2-rail.  There was some conversation here about special considerations for 2-rail, perhaps you're running across those.

 Yeah, I'm going to agree for now. I thought it was strange when I removed the TMCC engines and still had the problem. Why still with just the base? Maybe something inside?

Do you have the serial cable connected?

 No, just using a cab 1.

I think Marty is talking about the serial cable between the TIU and command base to allow you to control the TMCC locomotives with the DCS remote.  Is that a no for that cable?

 No serial cable yet.

And you are definitely adding it to the track common?

I'm just going through things in my head.  I've never had TMCC affect DCS.

Joe,

Would connecting the tmcc to all channels make a difference?

Since the TIU's BLACK channel Commons (-, if you're running DC) are not connected inside any TIU except the original Rev. G (unmarked), you need to connect the TMCC signal wire to the BLACK terminals of all of the channels on which you want to run TMCC.

I would suggest that you connect the TRMCC signal wire only to the TIU output channel's Common/-, since I cannot think of any good purpose that would be served by passing the TMCC signal through a DCS signal generator.

At the same  time, also be sure that the RED TIU channel terminal input has AC Hot (DC +) and that the BLACK terminal has AC Common (DC -).

Missed the 2 rail part. 

 I figure this is not the norm. both work on their own. It just seems like the base is interfering with DCS? Maybe some ground thing?? The TMCC engines run great??

 Maybe just a two rail problem?? I have not made Carl's mod yet for signal on both rails. Maybe that would help?

 Now that's wierd. It's working with the tmcc on channel 1 output black lug. The channel is not even used! That's the reason I connected it there as it was easier. I pulled that channel when I got a second TIU for my G scale. The O scale is on the other three channels!

 Hmmm, I'd better reconfigure things and try again. Maybe the empty channel is trouble? How am I getting signal all around?? WOw. I'll be back with more after I rewire. Why's everthing a huge...... Joe

 Ok, so I add the TMCC base signal to the three black output lugs of the tiu's channels I'm using. When the TMCC base has power, the DCS remote says "check track" then "engine not on track" when I start a DCS engine. When I kill the power to the TMCC base, all's fine again?

 O gauge two rail on AC power. 2 Lionel 180w bricks. A third tiu channel is " jumpered" for the engine yard.

 How do I determine what's hot on the brick's output. I followed the wiring diagram on the brick. Maybe it's swapped?

Joe,

If you're running AC, it's not all that important whether transformer Hot or Common goes to the TIU channel inputs, as long as it's the same on all channels. Just make certain that the bricks are in phase with respect to each other.

Also, make sure that the TMCC base has a good earth ground. Some find that the base has to be plugged directly into an outlet, rather than into a power strip.

 It is plugged into a strip right now. I thought that it worked so well for the TMCC signal, it was not the problem. I should eliminate that possibility.

"Some find that the base has to be plugged directly into an outlet, rather than into a power strip."  Good point Barry, can't say I've ever seen this point before.

Jack

Do you know how to phase the transformer?  I would think you'd notice other issues if they were out of phase, but maybe not. 

Connect the "common" of each transformer together.  Using a 18V bulb, connect that between the hot terminal of each of the transformers to the other one.  The bulb should not light or light very dim.  If it's bright, they're phased wrong.

 I moved the TMCC base to a different outlet (with a good ground) trying to eliminate things. Same results. I'm running the two of the same Lionel bricks in phase as far as I know. Each powers half the mainline. If they were out of phase, I would think I'd have more troubles. I'll check them again anyways, to be sure.

I thought the issue was with the DCS signal...

If TMCC is working fine I wouldn't think that would be it

Also, make sure that the TMCC base has a good earth ground. Some find that the base has to be plugged directly into an outlet, rather than into a power strip.

 Bricks are in phase. I tied the blacks together and got zero volts with my meter across the reds. When I switched the one black with a red, I get volts across the other two.

Marty,

If TMCC is working fine I wouldn't think that would be it

The issue seems to be the iteration between TMCC and DCS in a 2-rail, DC voltage environment.

 On Carl's suggestion, I'm moving the point of the tmcc connection around to see if that helps. It maybe a clue as I connected the tmcc base to a terminal distribution block on only half the main's wiring. The Yard is separate and so is the other half of the main. The TMCC signal goes all around? The only clear way I see this right now is if the commons are tied at the tiu outputs.

 I will have to test my layout's wiring to see if something else is going on to tie these together. Not sure why this would matter? Not sure how DCS even knows it's not a three rail environment. I'm going to get in deeper.

 At the least, I could have a switch to run each at thier own time. Technically, I can't see why the problem here only. I'll talk to other 2 railers.

This may not apply so pardon me if so. There was a mod on the "S" scale forum to connect the TMCC signal to the 2 rail track by connecting the rails to the "U" terminal through a capacitor. One from the "U" terminal to each rail to put the signal on each rail. If this was tried with DCS on the track it could easily short the DCS signal out.

The only other thing I can come up with is some kind of problem with the TMCC base output circuit that somehow puts a ground on the line. If you can I would try another TMCC base.

Al

I'm wondering about this also. It helps to narrow things down. I never did the 2 rail mod with the caps yet as my base just came in.
 I also want to swap out the tiu with my old one. Just in case there's some mod with the new "L" version. I'm trying to think this thru to get to the reason. If it works in three rail, then some difference is showing up?

 A letter I shared with John S. to thank him for his help:

" Thank you John, That's humbling. I think I just got it and I'll post the results on OGR. Carl Tuveson also emailed me earlier with a suggestion to find the "sweetspot" to add the tmcc signal to on the layout. Coupled with what you described, it hit me to go to the farthest point away from my engine yard where all the DCS engines are parked. This area also has my car yard with sidings for leaving trains.  I was moving it closer before! So with the grounds connected already in that blocked area it occured that the tmcc signal may be too strong? I moved the base from the first spot of the centrally located TIU, and finally put it in the farthest block away from this area. Now the TMCC struggles a tiny bit at the next long block's end with flickering lights, but two test engines runs as they should. I chased a tmcc switcher with a DCS ac6000. One small area also made the MTH check track appear. I can live with that. Maybe the blocks are too long now?"

 So it's working and I'm not ready to mess with it!! Thanks to all. Carl Tuveson and John Sethian, Barry, MartyE and gunnerJohn, I appreciate your suggestions. It's great you guys stay with it and volunteer info. This place still rocks! Joe

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