MTH DCS System

Question, do you have power drops about every 14 or so track joints! What you could do is test the signal strength on your DCS Remote in different areas of your layout.

Hey Mike, thanks for tuning in, I can’t say for sure if I have power drops every 14 tracks but I’m closer to every six feet approximately and I have checked my signal strength and most of my track, except for sidings stay in the 16-17 volts AC range.

Sounds good, but do you know the DCS signal strength? You have to use you DCS Remote to get to it. The best is 10. I have been able to run at signals of 6.

I suspect you're losing signal through the track joints, plus you're probably getting signal degradation due to having multiple feeds within the same track block. Separate your feeds with insulated track joiners. Make sure your regular joiners are nice and tight, and you should see signal improvement.

What version of DCS is your TIU?  The older ones (ones with a RS-232 port, not an USB) have track signal issues.  We had similar problems as you until we put the "magic light bulbs" on the layout.

If you haven't wired with DCS in mind, you can have "dead" spots where the DCS signal is weak.  This is a very common issue with DCS.

This topic was in the 3-rail scale category rather than in the MTH DCS category so we moved it.  PLEASE post topics in the most logical category based on the main subject of the topic.  This way it is much easier for others to find in future searches in specific categories.

Maybe I can help (even though as of yet I don't have DCS running), have done a lot of reading, read the forum posts over the years and yep, have the magical DCS companion book. They kind of sell command control as you attach a wire and you are good, but from everything I know, that is kind of like paint that covers in 1 coat....(I suppose if you have a loop of track it might work that way...).Things I have pulled out of all of this:

1)With DCS you can only have 1 signal wire per district/block . My layout to be is wired block style, so I had the obvious thought, well, just attach the DCS signal wire to the power wire going from the block control switch to the block. Problem is I use multiple drops, so would have multiple DCS signals. Unless you only have 1 power drop/district(block), make sure the dcs signal wire is unique. Nothing wrong with tying it to one of the drop wires going to the third rail in that block, you don't need to solder it seperately.

2)Another thing that seems obvious,but is wrong, is to have a buss wire for the DCS signal and tap off off it. DCS companion (and other people) said best way is the star arrangement in the DCS book which basically means the drop to each district goes back to the TIU (usually using a terminal block).

3)Keep the power districts as small as possible, so the DCS signal isn't covering a long run (basically use smaller rather than larger blocks/power districts). The signal degrades over distance because of the track connections on the third rail. Some people get around this I have read by soldering the rail to rail connection in a district, but to me it is easier to have more, smaller districts/blocks (it is how I am wiring my layout).

4)The track power is not what people are talking about. If you are seeing 17vac all through, that is fine. What they are talking is the DCS signal strength (basically identical to the strength of a radio signal 'in the real world' as a function of where you are relative to the transmitting antenna). I seem to recall the signal strength is measured from the old DCS remote (DCS is a 2 way signal, you send a message to the engine, it responds, the signal strength is actually the return ack message strength as the TIU sees it). The DCS app using wifi that is now standard has signal strength under 'Functions'. You would measure that (I guess) by having an engine on the affected section of track and seeing what the signal strength looks like. Manual says anything above 5 should be fine, higher the better.

Again, just what I have processed with my research for how to wire my layout for DCS and there are experts on here, this hopefully is just to give you a conceptual idea of how this works, since I am kind of in the same boat, learning.

Hey there Matt, I do have a lot to track on my 2 ovals on the layout but if I use insulated track joiners, won’t it drop power on those particular tracks. I haven’t installed any insulated track joiners as of yet and on my layout I haven’t used any additional block settings yet, right now it’s 2 ovals, one with O-72 curves & one with O-81.

I suggest you start at page 58 of the DCS O Gauge Companion 3rd Edition and read about the star wiring and how blocks are configured.

One shot from that book illustrating blocks.

Sounds like that might be a good idea, thanks John

@marshelangelo posted:

Hey there Matt, I do have a lot to track on my 2 ovals on the layout but if I use insulated track joiners, won’t it drop power on those particular tracks. I haven’t installed any insulated track joiners as of yet and on my layout I haven’t used any additional block settings yet, right now it’s 2 ovals, one with O-72 curves & one with O-81.

Yes, it will, but the idea is that each of those "blocks" is going to be independently powered from the others.

The basic issue with DCS is that if you have multiple feeders going to a loop and the loop is not divided into sections (blocks), then an MTH/DCS engine can get overloaded and "confused" (for lack of a better term)  in the sense that it's getting too many DCS signals and instructions from a bunch of feeders all over the loop.

The solution is to divide the loop into separately powered blocks so that the engine only sees the DCS signal from the block that it is currently in.

Let's say you wire your TIU output into a 12 or 24 port terminal block like the one shown below. You then isolate a section of say five 10" track sections by using insulated track joiners or just cutting a small slot in the center rail in the two end sections of track. Now that track section (block) is isolated from the rest of the loop. You then run a pair of red and black wires from one port of the terminal block to the middle track piece in that block and now that block has both power (voltage) and a DCS signal for any engine that crosses into that block.

You then repeat that pattern for as many block sections as you need for that loop and you are now correctly wired for DCS running and there's no chance of an engine becoming overloaded with multiple DCS signals from too many feeders because it's only getting the signal from the isolated block that it is in or at most two blocks when the engine is straddling two blocks.

In addition, by limiting the connections from the terminal block to just one track block at a time, you're improving power and DCS signal strength.

Gentlemen, 1st and foremost THANK YOU ALL, the explanations provided have made the block theory clearer. I will read all of these responses over again in addition to the DCS Companion. I have an MTH Big Boy that I was gonna send out for a check up or put it on the shelf until further notice. I was adding more feeder wires onto both loops for continuous signal strength and everybody was working except for the Big Boy which was running sporadicmnally, starting and stopping. However, all of my MTH TRAINS have to start on 1 particular track section and then I added another power feed to the O-72, to make things better.  This problem isn’t prevalent with my Legacy or 3rd Rail locos. I have 18 power feeds per loop on 1 terminal block. I guess I was wiring as a computer tech using the star pattern, whereas when used with trains the setup involves insulated rail joiners. Oh, my TIU has the old RS 232 port.

@marshelangelo posted:

This problem isn’t prevalent with my Legacy or 3rd Rail locos.

TMCC and Legacy have totally different signal paths, so DCS specific issues don't affect them.

@marshelangelo posted:

I have 18 power feeds per loop on 1 terminal block. I guess I was wiring as a computer tech using the star pattern, whereas when used with trains the setup involves insulated rail joiners. Oh, my TIU has the old RS 232 port.

After my track is laid and the drops installed, I just take my Dremel and chop the center rail joiner at the appropriate places for the DCS blocks. This is using Ross/Gargraves switches & track, YMMV if you use different track.

FYI, all TIU's have the serial port, the Rev. L also has the USB port that the earlier versions lack.

If you still have weak signal after doing correct star wiring, you can make and install Susan Deats Filters to improve signal strength. These can be very helpful with older (Pre- rev L) TIUs like yours.

Bob

Another issue I experienced with my layout is that if I had more than about 8 or 9 track sections running from the terminal block illustrated earlier above, I had serious signal strength issues. By limiting the number of isolated track sections to lets say 9 or 10 per terminal block, with one TIU channel driving each terminal block, my signal strength issues went away. This means that 9 longer sections had a better signal strength than 14 short sections. I was isolating each section by cutting the center rail, and had a ground wire of the same length as the center rail wire for each terminal block connection. Having a good track pin connection was also very important as mentioned earlier.

Hi Greg, not to dismiss what everyone else is saying, due to the fact that I was not able to afford all the wire needed to star wire I ran a bus wire system on my layout. I have power drops between all my switches to make blocks and then every 8' or so. I still run my layout the same way with 10's almost on every section of track. Just saying.