ADDITION of TMCC ENGINE DESTROYS DCS SIGNAL

Try adding  a 22uh 4 amp  choke to the engine in series from from the track power.

Dale H

Why is a good question.  It happens with some TMCC equipment, but there doesn't seem to be a repeatable pattern.  I have two Weaver engines that are identical except for the cab number.  One has no effect on the DCS signal and one destroys it.  I suspect it might be some tolerance creep in the TMCC components.  Just a guess.  But as Dale posted, adding an inductor between the input power and the board will cure the problem for that piece of equipment.  It's a bit of a pain, but thankfully it's not a wide spread problem.

There are also a few other items that can cause the same effect.  I believe the flasher circuit in an Atlas caboose has been mentioned.  I've also seen the problem with a MTH RK operating search light car.  Again, the inductor is the cure.

Constant Voltage lighting on Atlas product as well as some newer Lionel items has been known to cause a problem. The choke seem to be the fix

Wonder why that is happening.  We run a full mix of TMCC and DCS locomotives together on the layout using each systems controller without any problems.  Sometimes on the same track even.

I also have had problems like this...  In one particular circumstance, two completely separate and isolated stretches of track are being powered by the same TIU.  When I run my Lionel Amtrak Acela on one of the "circles" of track, the DCS signal on the other "circle" is weaken enough so that I can not operate more than one DCS locomotive on that track.  When I try to get another DCS locomotive to run, I get the "Engine not on track" error message.  When I move the Acela off of that shared TIU, the DCS signal goes back to 10 and I can run multiple DCS locomotives!

Fortunately, I have purchased a few extra TIUs so I am going to devote one TIU for each line so that each has a separate DCS signal isolated from one another.

Alan

I think Dale is onto the solution, this has been reported before.  Some TMCC locomotives, and even some illuminated rolling stock affects the DCS signal.  The addition of the choke usually solves the problem.

John,

 this has been reported before

It sure has, in the DCS O Gauge Companion, both editions. In the second edition, it's on page 152:

Some, but not all, TMCC engines will degrade the DCS signal of any PS2 engine with which they are in close proximity. This effect varies both by individual TMCC engine and by the distance between the TMCC and PS2 engines. In many cases, an RF choke inserted in the Hot wire between the pickup rollers and the TMCC engine's circuit board will correct this problem.

Some lighted cabooses, most notably those manufactured by Atlas O, may degrade the DCS signal, as may some engines or passenger cars with constant voltage (CV) lighting boards. Again, an RF choke inserted in the Hot wire between the pickup rollers and the circuit board in these cars will generally correct this problem. Although a number of different RF chokes may be effective in reducing interference from CV boards, one that has an electrical value of 22uh (micro henries) is known to work well.

This and a whole lot more is all in "The DCS O Gauge Companion 2nd Edition", now available for purchase as an eBook or a printed book from MTH's web store site! Click on the link below to go to MTH's web page for the book!

Barry, I knew I read this somewhere.   It's been talked about in the forums as well, so it's covered both ways.

As recommended, I installed a 22 micro henry choke. Problem solved. Onto the next problem.

Thank you to everybody who responded.

Just make sure the choke has adequate amperage capacity for the job. The one for the engine should be at least 4 amp and this will take up a bit of space. Some Atlas locos are pretty tight under the shell and fit could be an issue. If you can isolate the CV circuit for the lighting in the engine  and install a choke there,a much smaller one can be used. In a caboose the choke can also be small. Mouser and other electronic supply sell these for about $1 each or less. The 4 amp ones are a bit more.   

A picture of the choke used for the caboose and passenger car lighting is in this post.

http://www.jcstudiosinc.com/BlogShowThread?id=487&categoryId=

Dale H

Is there any reason we would not be having these problems on our layout, something we did in the wiring?  We have Weaver, MTH, 3rd Rail, Lionel that we run all over the layout at the same time using both the TMCC and the DCS control systems, along with the Atlas blinking caboose and don't encounter the DCS signal problem?

Not trying to be a smart a__ just wondering why? 

You didn't do anything unique or magical.  You're either just lucky or you have the problem and just never noticed it.

I've never measured the DCS signal strength while running the two systems together.  Could be it is low but doesn't impact the locomotives ... next time I've the layout fired up I'll check it.

Kerrigan;

I also was told the MTH Rotary Plow causes signal loss, but I tried mine one day and saw no effect on my signal.

It could be that the signal reading of 0-10 is not really the range.

If so, and 10+ reads 10 then losing some is no problem if you had a 10+.

Just an ad hoc theory that would explain my results.

Russell,

It could be that the signal reading of 0-10 is not really the range. If so, and 10+ reads 10 then losing some is no problem if you had a 10+.

 

Just an ad hoc theory that would explain my results.

Unfortunately, you need a different theory because that one's wrong.

Dale H,

If you are still monitoring this, how can I achieve 22 micro henries at 4 amps by using the physically smaller lower amperage rated chokes? Do you know the stock number for the items that you suggest?

They would be 2 different chokes to use. There are numerous choices on www.Mouser.com 

Example for passenger car or caboose lighting with circuits that use capacitors here are some 560 ma ones ( .56 amps)

http://www.mouser.com/ProductD...jEkrAJ3p5ReJIFMuo%3d

Example for input to an entire engine circuit engine here is a 6 amp one

http://www.mouser.com/ProductD...2vGXnf%252brGgCYM%3d

Keep in mind I am not an electrical engineer and because of the proprietary nature of the DCS system,these are only educated guesses as to impedance and not values based on any scientific engineering or calculations. The amperage should be sufficient as a 6 amp inductor could handle the current as the engine would use over 100 watts at 18 volts if 6 amps were pulled,the engine would not normally pull anything close. Perhaps one of the EEs on the forum could give their input.  Dale Manquen of the Forum explained once that capacitance could cause signal reflection so perhaps the values are not that critical as it would be in other applications.

What puzzles me is that most engines with sound, even MTH engines probably have power supplies in the boards with capacitors to supply + 5 or whatever is used.  Perhaps PS2 electronics have chokes in built in the boards. 

Signal issues vary from layout to layout as I have read. I run conventional so this is not an issue for me and I have no direct experience. I have made lighting strips for people who use DCS and have no reports of signal problems,but I installed the chokes in each strip as in the post linked before for caboose lighting. If you get stuck I may have some chokes in my parts drawer,I would have to look my shop is a mess right now. However the 6 amp one listed does not seem that big.

Dale H

 I have several Lionel and TMCC equipped engines and cars. I thought that each did not hurt the signal. When I get the right combinations on the track, it does. Even the constant light board in my MTH Allegheny can tip the scales if the signal is weak enough. Any one (or two) on their own seems not to be a significant problem.

 I added a TMCC base to my 2 rail layout and saw problems. I bought some 3 rail track and I'm experimenting. Seems again, if the signal is borderline or weaker, even the tmcc base weakens it. Don't know why I see this when others don't. Maybe because I have so many DCS engines on the track now while using minimal TIU channels. I even added the new TIU. I think it requires more TIU channels activated on the layout to overcome any signal killers? I still believe more engines need more TIU channels. I have not proven it.

 I got lazy and still have not added chokes in the offenders. Seems easier to keep the Lionel on it's on loop.

Thanks a lot guy...  I try to find all the day what wrong on my layout with this ERR TMMC equipped loco that kill my DCS.......  and I found this post.  

The solution for universal operations is to add the RF chokes to the offending engines.

Well, yesterday I made a lot of work on my layout. I add more tracks , create 3 blocks, install the detection system of those blocks and add TMCC command base. For the detection I install capacitor between the insulate rail and the other external one to allow the tmcc signal to pass. I also add filter at each end of the track ( to replace bulb) . So when I try a DCS engine and I see ot lost signal after few feet, I try to find first what I did wrong, I even bring a scope on the layout room,  I Google a lot to find solution and found nothing yesterday afternoon, it's only last night that I found this post..... The funny part is that I read the book of Barry, but i guess I don't pay attention to this part. I place an order for the chokes. 

Capacitance between the center and outside rails will kill the DCS signal, it won't affect TMCC however.

The capacitor is between the external rail connected to the TIU and the isolate external rail  not connected to the TIU, so the capacitor let the tmcc signal pass but block the 60 hz power. Nothing betwen the center and external rail  Mike Reagan explain it at the end of his video 

http://www.youtube.com/watch?v=UQ-hiIvPxVs

I checked out the end of the video.  Right, I thought you were talking about something else.  Seems like a good idea, but I wonder if those are separate DCS channels from a TIU, how would that affect the DCS 3.27mhz signal?

I don't install the capacitor in series like Mike show in the video ; since I run a bus under each rails ( #12 gauge wire) and the detection rails as also a bus wire and each pieces of fastback as a feeder connected to the bus, I simply connect 1 capacitor between each bus of the detection and the outside rail , of course each bus of detection are separated,  but the outside rail is continuous all around the layout . The power block finish at the same place as my detection block, I plan to use 4 TIU as my layout will grow, so I will have 16 signal blocks .  You can see the capacitor in green. On the pic I show 3 blocks. 

It work  well 

Sounds like a plan.