# DCS - ignoring the response from a locomotive



## Tom Bray (Jan 20, 2009)

I was talking to a sales person at one of the hobby shops around Atlanta and was complaining that my biggest issue with the DCS system was loosing the response from the locomotive as it went around the the track.

He indicated that there was either an upgrade or an option setting that would disable the controller from requiring the response to come back. 

This would be a major help since often I will loose an engine after a derailment and the system won't let me drive it back to where there is a signal. There are certain spots around the track that have never had a great signal but there is plenty of power available. It seems to get much worse when I have the passenger cars on the track which all have lights in them. The Hudson locomotive is the worst, the F7 doesn't seem to have anywhere near the same problems. 

So I went looking to see if there were any updates and all I find is the one from April of 2009. Is there something else out there or is there a setting that I don't know about that will help with this?

Tom


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## Rayman4449 (Jan 2, 2008)

I recall discussing the issues with your setup at length some time ago. As indicated before, you shouldn't be having any signal issues with the limited number of linear feet you have. 

The information on the setting you need is in Section II of the DCS Tips page on my website. We discussed the passenger car light issue and the information related to that is also on my site, but again with the size of the layout lights should not be causing an issue.


Raymond


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## Tom Bray (Jan 20, 2009)

Raymond: 

I went through your website recommendations last year and with the exception of getting a new Bridgewerks power supply, I have tried most of your recommendations. The layout worked pretty well last year, there were some issues but they weren't a big deal. This year it is difficult to get things to work reliably at all. 

The F7 runs fine, the Hudson is a royal pain. It doesn't seem to matter where I put the Hudson on the track either, it can be on top of one of the power feeds, it can in the middle of a segment, or it can be near one of the lights. I have tried turning the Hudson around, reversing the track voltage, etc, it behaves the same way on the outdoor layout - it takes off as soon as I apply power to it. If I take the Hudson inside and run it around on a small oval test track, everything is fine, it hears fine, it reports back fine, etc. The oval test track is just an 8 foot loop made into an oval, I use the standard Aristo SS track joiners and don't screw it together. If I were to send this engine back, I am sure it will be a "No Problem Found". Since the F7 works almost up to expectations, I seriously doubt it is the TIU. 

The F7 even ran fine in the snow last February. This year the F7 doesn't always report back fine but hears the commands and changes its behavior accordingly. 

The outdoor layout is SS and the outside loop is right around 120', the second inside loop is maybe 5 feet shorter, this does not include sidings which add another 40 feet or so. Each loop is broken into 4 sections with at least one set of lamps across each section. Last year, once I got all this installed, I had communications around the entire loop with only a few places where it was a little shaky. A lot of the track is ballasted and tonight it was probably a little damp since it rained all night. 

One thing I did change was the type of terminal strips I was using to distribute track power, back in the spring. Originally I used ground bars used in power panels - they were great except they liked to rust and several decided not to unscrew when I was making some changes. The new terminal strips are the standard pair of screws strips with a shorting bar running along one side, Radio Shack sells the terminal strips and the shorting bars. 

I have tried a number of different power supplies. Whenever I do test a supply, I try it both through the TIU and using the TIU in parallel with power supply output - I usually see a small improvement by having the TIU in parallel with the main power. The best performance was actually a switching supply but it only puts out a maximum of 15V. I picked up a small linear supply that is rated for 4A which I use primarily for test purposes but it doesn't perform any better than the MRC Power G. 

One thing I haven't tried is disconnecting sections of the 2 ovals and see if there is an area or two that are causing difficulties, such as causing the whole system to have reduced signal levels. I did try disconnecting one of the two ovals this evening and it made no difference for the Hudson, it just started up when I powered the track up. 

Of course, while I am horsing around with getting the DCS system to work, I have two DCC trains that are just running around the layout, happy as can be (one is the slave F7 that I converted). Of course the DCC system runs on track that has very few of the refinements that have been implemented on the DCS loop, in particular there are a lot less Split Jaw connectors. 

If there were an easy way to blow the whistle and turn the bell on and off using DC, I would run the Hudson that way and bag the DCS part - then I could simplify the wiring, reuse the track isolators for block control, etc. 

By the way, tonight I was just running the engines, no additional cars.


Tom


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## Greg Elmassian (Jan 3, 2008)

The power G is not filtered, just rectified. I'm wondering if it is noise on your power supply. 

What supply do you run on the indoors loop? 

Raymond is the expert, but I'm curious about the situation. 

Regards, Greg


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## N1CW (Jan 3, 2008)

*Tom/et-al*

*>.....Each loop is broken into 4 sections with at least one set of lamps across each section. ...snip...*
*Like your trial solution, the "LAMP" addition did make an improvement BUT...
..you know the rest of the story...**







* 

*I have TURNED OFF THE LIGHT and replaced them with a "Marriage found in my JUNK BOX" *
*or a Radio Shack near you. A single resistor and cap in series **across the TIU output and*
*another set opposite the feed points **on my two 140' SS loops......9>10's.....aaaaahhhhhh. 

The 'Green Chicklet FIX' is in my pocket when I visit other DCS layouts with signal issues.
*

*"Your mileage may vary"......OH and only the light bulbs objected to this marriage *
*since they are now just in the roof's of the Aristo H/W cars....*

*







*


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## Tom Bray (Jan 20, 2009)

The Power G was used in the indoor test since that is what easily wires into the TIU. The transformer currently has, in an external box, a second bridge rectifier, a 4700uF (or close to that) capacitor and an second forward / reverse switch. The diodes keep the unloaded voltage from getting to high (it would go to 28V if I put the capacitor inside the transformer). During several tests it seemed that the filter box appeared to be helping but it really makes the voltage fluctuate more than the transformer by itself. 

I'll try a few of the resistor cap sets and see if that helps. It would be nice to tame this thing - I am not really interested converting the Hudson to DCC until MTH, if it ever does, releases the PS3 for 1 Gauge. The Hudson is still my favorite engine but it is way to finicky. 

Tom


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## Chucks_Trains (Jan 2, 2008)

Out of curiosity why do you feel the need for a box of electronics that the Power G is hooked up to? I know of 2 other DCS layouts that are being powered with a Power G with no problems.

Just a note that I've found that Aristo-Craft switches will tear the heck out of a DCS signal. A local friend is powering his layout with a MTH Z4000 AC Transformer and he was only getting 3-4's on his layout. He gutted the Aristo switches and the signal came up to 9-10's









My indoor layout had 6 Aristo #6 switches and I had a heck of a time maintaining a decent DCS signal until I swapped out the Aristo switches with USA #6's. I never liked the Aristo switches esp. the way they're built but I wish that I would have kept them and experimented with them...I think it has something to do with that polyfuse that's on the bottom of them.

Ray, I never tried that DCS fikter but you have good luck with it


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## Greg Elmassian (Jan 3, 2008)

I can sure understand a noise problem with Aristo #6, with the possibility of shorts at the gaps between the "point rails" and the frog, the microswitch and the polyfuse, and the use of screws that rust to make the connections underneath. 

I would not expect problems with the WR switch though, Chuck any negative experiences with Aristo wide radius switches and DCS? 

On the filter, it would seem that the resistor/cap combination would be more effective at reducing noise. The capacitor is basically a "short circuit" to high frequency noise, so it should be effective at reducing HF noise. 

If the lamps is in series with the power lead (please forgive my lack of knowledge), then the inductance in series with the track should also "block" HF noise. 

Both electrical methods can work pretty well, but I would think that the capacitor setup has an advantage of not adding resistance and affecting track voltage/current. 

Thanks, Greg


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## Tom Bray (Jan 20, 2009)

The box outside the Power G was an attempt to make it look more like a traditional power supply with some filtering. The basic transformer is essentially just that, a variable transformer, full wave bridge and a direction switch. It has been part of my various experiments to improve and/or maintain the performance of the DCS system. Raymond's website indicated that the Power G was marginal but works. 

In the progression of the layout, when I put the first loop together that ran on above the ground things worked OK. Adding the second loop and backfilling some of the layout with dirt and ballast dropped it down to unacceptable which was when I started breaking the system into sections and adding termination lamps, I also added a whole bunch of Split Jaw joiners. That got the system back to pretty good. This year, depending on which engine I run, the F7 is OK, the Hudson isn't hearing the DCS signal at all regardless of what I do, at least on the outside layout. 

The lamps and the proposed filter network go across the track or across the output of the TIU. A number of people have indicated that the lamps work better than an RC filter so I never tried the filter. I recall that the carrier for the control signal is something above 3MHz, having terminations should cut down on reflections and make the rail system look like a resistive load instead of an inductive one with a high VSWR. 

 Unfortunately the switches in that portion of my layout are all Aristo #6 switches but ... I don't run any power to speak of through them. They all sit at the end of sections, actually the 2 power zones that are on the on the bench area. There are 8 #6 switches on that area of the layout. Maybe I'll take them out and see if that fixes it somewhat ... maybe clean them up a bit. That section of the layout is built around the #6 design so swapping them with out, with maybe a Train-Li one, isn't a great option. 

Tom


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## Greg Elmassian (Jan 3, 2008)

Tom, check the gaps between the frog and the "frog rails"... it's an air gap, and it can close with expansion and contraction. That can cause shorts or at least some minor arcing, which should be a perfect source of noise! 

I put a piece of credit card or thin plastic in the air gap and trim to fit the rail contour with an X-acto knife.You can see a bit of white plastic in the far joint here, before trimming.











You might also want to test the switches that the microswitch/power routing to the frog is working, just a voltmeter between the frog and the appropriate stock rail, tested in both switch positions, normal and diverging. 

That should be easy to do and might yield quick results. 

Regards, Greg


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## Tom Bray (Jan 20, 2009)

I'll take a look at the switches either tonight or tomorrow. It will probably be tomorrow but I'll pull a switch or two tonight. I would think that if they were shorting out I would see issues when I configure the layout to run under DCC too but maybe they are too intermittent. 

My standard test for the layout is to start on the bench with the outside loop and run an engine all the way around through the switches, eventually ending up at a point outside the layout next to the house - unfortunatly the innermost loop and the section that goes outside the loops isn't configured to support DCS so it is either on DC or DCC that I can run the test. It proves that everything is wired correctly with the correct polarity. 

I have been known to run things through the switches the wrong way through the #6 switches in the past and that doesn't seem to have effected the DCS operation when that happens. 

Tom


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## Rayman4449 (Jan 2, 2008)

Tom, what lights are you using at the TIU and track level? (volt rating / amp)


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## Tom Bray (Jan 20, 2009)

I don't remember which lights I have in there at the moment ... I had enough of the recommended ones to do the layout, then several stopped working and I replaced them with the 28V radio shack variety. For some reason they didn't last very long as I expected. Maybe when I was experimenting the first time with filtering the Power G transformer I over stressed them - the light were the only thing connected when I was playing around. When I changed the lamps from the Radio Shack variety I put in there the first time, it didn't seem to make much difference, both provided about the same signal levels running around the track. I went around last spring and fixed bulbs that didn't work but I only had the Radio Shack variety. 

I pulled all the #6 switches from the layout and looked at them. They all have the gaps where they belong and I had treated all the connections with some grease so they are all still in good condition - no rust or corrosion. I found one that that guard rail is no longer attached at one end which I will fix before they go back in place. They still have the fuses in place - I am reluctant to remove them. I was looking at the option of removing the micro switches and leaving the frogs un powered but I have an Eggliner and a small HLW engine that won't make it through the #6 switches if the frogs aren't powered. 

Also all the switches are only fed from one side of the layout, the other 2 "sides" all have isolators and separate feeds. So any engine that goes through a switch has at most 12" of track before it gets powered from a different path. 

Pulling the switches is something I have been meaning to do because I need to fix the ballast on most of the tracks on the bench part of the layout. 

Maybe some of the feed connections have gotten corroded ... although most have either grease or liquid tape on them. I'll check those when I put things back together. 

Tom


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## Tom Bray (Jan 20, 2009)

By the way, there isn't a light at the TIU right now ... having it didn't seem to make any difference but around the layout did.


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## Rayman4449 (Jan 2, 2008)

Tom: 

From what’s been described between the behavior of the F7 and the Hudson it does sound like something is not right with the Hudson, it shouldn’t be acting any differently than the F7. Second, to have an oval of only 120ft result in a ‘Check Track’ you clearly something going on to reduce the track signal levels (I know I’ve said this before) which is very odd as a loop that small should need nothing other than a single track connection and one recommended type bulb (of course I always suggest 100% clamps). Since you don’t have any issues with controlling the F7, changing the setting in the remote will get rid of those unnecessary messages. That’s how I run mine as it improves overall performance. What does a track signal test all the way around reveal with the F7? (how long are the various areas of what ranges) How about the Hudson? Also, can you share another photo or diagram of the layout? 

On the Hudson, I would inspect it to make sure you have proper continuity between the power pickup sliders and the trailing truck power pickups. I’d also check to make sure there the power pickup wires are in ok shape inside the engine leading to the board and that the wires are screwed into the sliders. If the wiring looks good then the PS2 board in the engine may have an issue. I’d be glad to test it on my layout in my own Hudson to do a comparison if you want.

What rev(version) is your TIU? 

I am very curious to hear how your outer oval would react with the polyfuses removed from all the #6 switches.(just removing the poly fuse is all that would be needed) I was very surprised when I first heard of it affecting signal. I’ve added polyfuses to the trucks on all my passenger cars to protect against cross truck shorts in derailments and they don’t affect my signal either active or dormant. (and my 11 car heavyweight consist has a total of 44 of them installed) Perhaps if you are willing to invest the time to remove them and then redo the track signal tests I think it would be worth the effort as this could not only point to a primary issue going on but would also be helpful to know for the future. I would do the track signal tests with the F7 and Hudson before you take them out. 

I think you will find that any connections that may have gotten corroded may not yield much benefit if cleaned. I replaced the ring terminal connectors that have been outside for 4 years that were oxidized at 3 spots (testing out a new method of connecting wires to the track) and noticed no difference in signal variations afterwards. I’ve seen a lot and done a lot of experimentation (because I like to tinker) and it always comes back to the power supply you’re using & light deployment as necessary… the PS is the foundation and clamps provide insurance you don’t have problems now and over the longer term. 

The fact you saw little difference between the bulb I recommend and the low amp radio shack is because the oval is so small that there is limited correction needed.


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## Tom Bray (Jan 20, 2009)

I am cleaning up the track and the connections. I found that several of the bulbs have managed to get water into bases and there is a lot of corrosion (none of this is good for RF signals) ... I am in the process of removing them for around the track and simplyfing the power delivery scheme. I am also replacing more of the standard rail joiners with clamps since I have a few spares. 

I can try removing 2 of the fuses but I don't expect that to do very much. 

I have never taken the Hudson apart but I can take a look at it. It is possible that it could have lost a set of pickup wires. Although it seems to run just fine on DC, no dead spots or other funny behavior.


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## Rayman4449 (Jan 2, 2008)

Posted By Rayman4449 on 31 Aug 2010 08:53 PM 
Tom: 

From what’s been described between the behavior of the F7 and the Hudson it does sound like something is not right with the Hudson, it shouldn’t be acting any differently than the F7. Second, to have an oval of only 120ft result in a ‘Check Track’ you clearly something going on to reduce the track signal levels (I know I’ve said this before) which is very odd as a loop that small should need nothing other than a single track connection and one recommended type bulb (of course I always suggest 100% clamps). Since you don’t have any issues with controlling the F7, changing the setting in the remote will get rid of those unnecessary messages. That’s how I run mine as it improves overall performance. What does a track signal test all the way around reveal with the F7? (how long are the various areas of what ranges) How about the Hudson? Also, can you share another photo or diagram of the layout? 

On the Hudson, I would inspect it to make sure you have proper continuity between the power pickup sliders and the trailing truck power pickups. I’d also check to make sure there the power pickup wires are in ok shape inside the engine leading to the board and that the wires are screwed into the sliders. If the wiring looks good then the PS2 board in the engine may have an issue. I’d be glad to test it on my layout in my own Hudson to do a comparison if you want.

What rev(version) is your TIU? 

I am very curious to hear how your outer oval would react with the polyfuses removed from all the #6 switches.(just removing the poly fuse is all that would be needed) I was very surprised when I first heard of it affecting signal. I’ve added polyfuses to the trucks on all my passenger cars to protect against cross truck shorts in derailments and they don’t affect my signal either active or dormant. (and my 11 car heavyweight consist has a total of 44 of them installed) Perhaps if you are willing to invest the time to remove them and then redo the track signal tests I think it would be worth the effort as this could not only point to a primary issue going on but would also be helpful to know for the future. I would do the track signal tests with the F7 and Hudson before you take them out. 

I think you will find that any connections that may have gotten corroded may not yield much benefit if cleaned. I replaced the ring terminal connectors that have been outside for 4 years that were oxidized at 3 spots (testing out a new method of connecting wires to the track) and noticed no difference in signal variations afterwards. I’ve seen a lot and done a lot of experimentation (because I like to tinker) and it always comes back to the power supply you’re using & light deployment as necessary… the PS is the foundation and clamps provide insurance you don’t have problems now and over the longer term. 

The fact you saw little difference between the bulb I recommend and the low amp radio shack is because the oval is so small that there is limited correction needed. 

To clarify (since I can't go back and ammend the post) I'll do it this way as I didn't mean that only three connection points had visible signs of oxidation.

"I replaced the ring terminal connectors in three locations on my large ovals (that have been outside for 4 years) testing out a new method of connecting wires to the track and noticed no difference in signal variations afterwards."


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## Tom Bray (Jan 20, 2009)

Here is a reasonably recent shot of the layout - it could probably be a bit more detailed but it will do. The two outside loops are used for running the DCS style engines. 

Yesterday I removed all the terminating lights and removed the two sets of isolators that divided the garden area of the outside loop into 3 parts. The loop now has one power section on the bench area (the part to right that looks sort of like a deck) and the rest of the track that has 3 sets of feeders going to it, these are on either side of the bench after the switches and then one in the middle of the left side straight away.

I put the Hudson on the track and powered it up. If the TIU is connected, the train sat there, it heard the TIU. I couldn't get an answer back from it to control it up but, at least there was some progress. I added a light across the feeder wires where the transformer connects to the layout. Behavior was the same, engine didn't move when I applied power with the TIU, but the remote couldn't find any engines on the track. Then I tried the resistor capacitor network described above and stuck it across the track just in front of the engine ... same behavior. Moved the RC Network across the lamp, same behavior.

At this point I brought out the F7 to see what it would do. I parked the Hudson on the siding, where it would power up but be out of the way, and tried again. The F7 and the Hudson stayed put when I applied power. The remote found the F7 immediately. I started up the F7 but left it idling. Checked on the Hudson and the remote found it immediately also. So I ran the Hudson around the loop - perfect 10's from the track signal all the way around the loop (I've never seen that before). 

I powered the system off and removed the F7. Powered the system back up and the remote found the Hudson. I ran it around the track again, this time the track signal varied from a few 10 down to a 2. The variation seemed to be sort of random - the lows and highs were often in the middle of a secton of track and it didn't seem to make any difference if the engine was close to or far away from a feed point.

I tried the F7 on the track again and the Hudson went back to clocking perfect 10's for track signal all the way around the loop (so it wasn't a fluke). I left the Hudson running around the track and fired up the F7. It too produced perfect 10's on the track signal all the way around the loop (the Hudson was in front of it moving the whole time).

So, I am not quite sure what to do next. Obviously if there is enough load on the track everything works great. 

I haven't tried just the bulb or just the RC network with the two engines on the track, maybe tomorrow night. The other thing is that the track that is out in the garden area is now fed in 3 places that do a home runs to the main junction point - I am not sure if this is optimal for either DCS or DCC. I also need to finish rebuilding the second loop and see if I can run engines on both at the same time and get similar results.

By the way, all this testing is with the TIU in passive mode. I also removed the extra filtering on the output of the MRC transformer. Things are about a simple as they can be. 

Tom


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## Chucks_Trains (Jan 2, 2008)

I get a better signal by using the fixed inputs/outputs.


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## rmcintir (Apr 24, 2009)

Off this topic but could you post (or point me to) some close up pictures of the elevated track suspension you've shown in your pictures. (different topic of course  )


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## Tom Bray (Jan 20, 2009)

I'll put together some pictures and post them in the appropriate forum. The track sits on 2x6 treated lumber. The supports have a 4x4 posts on the outside that for the most part sit on the ground (this is Central Alabama so there isn't much of a frost concern). On the inside of the loops there is a 2x4 uprights and 2x4 horizontals supporting the track and 2x6s. Everything is screwed together. Inside the garden are exactly the same structures but it has been filled in with dirt. The 2x6s are connected using 5/4 x 6" boards, this makes for a pretty solid connection and a 2 1/2" deck screws hold pretty well without poking through. Our property sits on a combination of gravel and clay so digging into the ground is no fun at all.


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## Tom Bray (Jan 20, 2009)

The update on the track situation and general performance: 

I replaced the home run feeds on the outside loop with a single loop that runs around the garden portion of the layout. I jumpered it where I either had a feed point or I had a set of lamps. The two end points both go back to the common distribution point, as does the track that is on the bench. The track sections on the bench are going to remain separate circuits because I plan on adding occupancy detection transformers (DCC) at some time in the future. 

With a single lamp and the RC network plugged into the TIU, the track signals range from a couple of 2's, lots of 4 - 7 and a few 9/10 readings when running the Hudson around solo. Putting on two passenger cars with all the lights brings the signal up to 9/10 all the way around the track. Track voltage ranges from a low of about 18.5V to a high of about 18.8 ... the lights on the passenger cars change brightness when running through the switches but otherwise the are pretty constant (probably the best test of how the layout is working). I didn't try running two engines tonight. 

It is hard to tell if it is running better or worse than with the 3 home run feeders but I think the closed loop may provide a better overall design. I will have to see how the DCC system performs on it. But DCC usually just works, even on the thrown together portion of the layout so I don't expect to see any issues there - as long as a 120 foot loop doesn't cause it to ring, it should be fine. 

I have control under DCS all the way around the layout and everything is currently happy. 

It sure is a good thing the price of copper has dropped, this change is going to be 250+ feet of wire before I am done. That is one of the reasons why I did the home runs the first time around - a lot less wire. 

Tom


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## Chucks_Trains (Jan 2, 2008)

I don't understand why you need all the power feeds as I install them only if there's a big voltage drop. Heck I've seen DCS layouts operate just fine with one set of feeds where the loops were over 200' in length.


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## Chucks_Trains (Jan 2, 2008)

Greg, I never experimented with any other Aristo switches..only the #6's.


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## Greg Elmassian (Jan 3, 2008)

Thanks Chuck, was just curious... they are electrically much "simpler". 

I worry a bit about extra feeds on such a small layout also, in my mind, if you got exactly the "wrong" spacing, you could have signal cancellation. 

Regards, Greg


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## Tom Bray (Jan 20, 2009)

I think I found the problem. I may have missed this as a no-no but I don't recall anyone ever mentioning it nor have I found any references to it ... I have been using wire staples to hold wires in place around the layout. If I want to run DCS reliably I guess I will have to use wire ties. 

This afternoon I dressed up the cables so that they didn't hang down on the ground (and across one of the lower tracks) using the staples (1/2 inch variety that are used to hold conduit in place - use a hammer to install them). When I went to run the trains this evening, nothing worked ... at least as far as the engines answering back. If the remote powered up and decided the engine was on the track I could run the engine around the track without too many problems, except for the remote having issues. It was bad enough that the remote was saying it couldn't communicate and started crashing, actually it was hanging up and to get it back I had to take the batteries out. I tried resetting the remote - bad idea because it would not let me add the engines back in. 

I was going through everything that I had done since last night when the system ran great, dressing the wires was the only thing that I did to all the sections of track. I pulled all the staples out of the entire layout. Things aren't quite perfect yet but it is back to where it was last night as far as performance goes. I was able to get the remote to find both engines but it didn't identify what they are, only their addresses, which is enough to run things around the track. 

So ... metal staples short out the responses from engines - Grrrrr. 

Now I need to get the remote to know about the engines again - I guess i'll do that in the house on a test track tomorrow. 

I am wondering if the buried cables are causing a similar problem. Right now almost everything is sitting on top of the ground but I was planning on making the wires disappear. The wires look terrible and I am sure the puppy will figure out that they make great toys for playing tug of war with. 

As a comment, I haven't had very many issues with voltage on the track, only problems with being able to talk to the engines using DCS. If I switch over to DCC or DC everything runs pretty well. There are a few places where the voltage would get a little low, these correspond to sections that haven't been upgraded with Split Jaw clamps (original Aristo rail clamps). Also the track is SS which doesn't conduct as well as brass does - by adding the loop of wire and jumpers I noticed that overall the track voltage is a bit higher and it is more uniform around the track. In the process of trying different things to get it to work reliably, I implemented many of the recommendations on Raymond's website, usually without much improvement. I got the system so that it ran acceptably for about 8 months then it got really bad sometime during the spring, that probably corresponded to when I added more dirt around the layout and started the design for the center area that will eventually include a small canal and a pond. In June I converted the MTH F7A Slave to DCC because I was getting very frustrated with the whole mess not working. 

Tom


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## Tom Bray (Jan 20, 2009)

As far as cancelation of signals go, if a single arbitrary loop fed at one point doesn't cause standing waves that interfere with the operation of a train, breaking the loop up into sections or just adding feeders to it shouldn't be any worse as far as signaling goes. It might be interesting to stick a network analyzer on a loop of track and measure the behavior, assuming the analyzer could deal with the ugliness of the readings. 

One of tomorrows tests (Sunday) will be to see if the system still does DCC well ... I have a feeling it will run just fine since worked great before I made these changes. 

Based on what I have seen over the course of this week, I don't think the the TIU or the engines have any particular problems with their operation or performance. The real issue now is whether the layout stays reliable and can I get the layout back to an aesthetically acceptable appearance while still having DCS work reliably. 

I have decided that I need to move on - this was my last gasp to get DCS to run reliably on my layout. I have other aspects of the layout that deserve attention. I still like the MTH products and will probably continue to buy them ... they may all end up with DCC decoders though. 

Tom


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## Chucks_Trains (Jan 2, 2008)

I use wire staples to hang all my wiring underneath my layout and have 9-10 signals all thru the layout. 

There are a few places where the voltage would get a little low, these correspond to sections that haven't been upgraded with Split Jaw clamps (original Aristo rail clamps). 
Why is that? Every body who uses track power stresses to use railclamps. Why try & cheat on this one most important fact? 

Raymond asked you what DCS version is loaded into your TIU & Remote but you never replied. Infact your openeing post refers to a dealer telling you about an update. Reason I bring this up is some firmware versions are terrible.


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## Tom Bray (Jan 20, 2009)

This is an offending staple. After I installed a bunch of these yesterday (18 to be precise), everything stopped working, after having significant success the previous couple of days. I removed the staples and it went back to working ... cause and effect? Essentially they stopped all responses coming back from the engines and degraded the signals going to the engines to some degree. None of the staples went through any wires either. 

I realize that other people have had different experiences and everything just works, I am not one of them. I take that back, when I brought home the DCC system, hooked it up and set the trolley on the track, everything just worked, it ran around all the loops with no issues, a major contrast to making DCS work. My converted MTH F7 running on DCC works just as well as the trolley does.

Right now the layout works great but I have wires dangling from the bridges and such. I also need to make the wires that are laying on the ground disappear before they get damaged by the puppy.

As far as rail clamps go, I add more clamps as the wallet allows. I figured out that I need about another 200 clamps to replace all the remaining track joiners, that represents not quite doubling what I have already installed. That isn't in the budget right now. Also when I have added another 50 or so clamps I haven't seen any measurable change in the performance of the DCS system. Prior to removing the segments earlier this week, the ones that were all clamps had as many or more problems than the ones that were almost totally joiners. The joiners are all installed with conductive grease and I go around and check the screws on a regular basis.

Tom


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## Greg Elmassian (Jan 3, 2008)

It could be the being parallel to the rails, and how close they were, and not the staple per se 

Try using tape to put the wires back in place and test, that will tell you the real reason. 

Regards, Greg


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## Tom Bray (Jan 20, 2009)

This is the new style wire hanger:










I don't have enough to do everything exactly like it was with the staples, but for the main lines they are almost identical, which is where I run the DCS based trains. 

I ran the trains last night for about 4 hours and everything ran great. This morning I took a few measurements with only the Hudson on the track.

There have been some changes in the track behavior but I am not sure I can explain them. I noticed that last night and I confirmed the same behavior this morning, is that there is a small section on the track furthest from the bench (the outside straight section on the left of the photo of the layout) where the track signal drops to about 1 or 2 and then immediately jumps back up. It doesn't seem to correspond to any joints, it appears to be in the middle of the track. The other interesting thing is that that section of track has nothing but Split Jaw clamps on it. The rest of the way around the outside loop, with the exception of the bench area produces 9 - 10 signal levels (it just so happens that the curves are still all track joiners - only an occasional clamp) .

The bench this morning isn't fairing so well. It is producing very poor track signals, mostly check track messages, etc. This is another area that I only have rail clamps installed, but it is fed by its own power. The interesting thing about this is that, when I have 2 passenger cars trailing behind the engine, the track signal stays very good until the last car clears the isolator.

In general, with the wires running along side the track and attached to the benchwork, there isn't any major behavior change in the DCS system. So, my original opinion is that the steel staples had something to do with shutting down the system - I have never had it behave that badly, regardless of how messed up it was.

I am beginning to suspect that there is a problem with the length of track and the power feeders interacting at the frequencies that the DCS is using to signal at. The reason I am suspecting this is when I change something one place, the behavior will change elsewhere in the system. I wonder if my MFJ antenna analyzer will deal with this.

In considering how the system runs, a major portion of the energy appears to be at 3.57MHz, which is the "chip" rate of the spread spectrum signal according to the patent. Right around 120 feet is approaching the half wave length of a radio signal at 3.75MHz that is running down a wire. Now there are a whole bunch of factors that impact how a signal travels down a set of wires, especially when it is close proximity of the ground. The 45mm track really looks like a transmission line, probably approaching 600 ohms if it were suspended in the air. A piece of zip cord probably has a characteristic impedance of 30 to 50 ohms, again if suspended in the air.

It would be my luck that I designed a layout that resonated at the DCS frequencies. If that is the case, it might explain why the staples had such a disastrous affect on the system, they broke the feeder loop into two 60 foot sections with a short feed section at one end (60 feet is around a quarter wave at those frequencies and has an interesting ability to transform impedances from one end to the other). It probably completely canceled or shorted out the DCS signals.

Tom


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## Greg Elmassian (Jan 3, 2008)

From an RF point of view, what you expressed and what you have seen make perfect sense. When you get near a multiple (or integer fraction) of the wavelength, strange stuff happens, you just cannot beat physics! 

The staples are weird, you would not think such a small piece of metal would make a difference, but you have proved that it did. My guess is that the signal was somewhat marginal already. 

Regards, Greg


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## Tom Bray (Jan 20, 2009)

I tried looking at the track using the antenna analyzer but didn't really find anything that would qualify as a smoking gun. Here are some thing, overall that I found:
[*]Looking into the track from the power feed point yielded a 2:1 VSWR at 3.75MHz. I could easily load up my ham rig into it and use it as an antenna. [*]Looking from the track back to the power supply, the readings in areas that worked had resistances of 5 to 50 ohms and a reactive component in the same ball park, 5 to maybe 80 ohms. My meter won't tell me if it is capacitive reactance or and inductive reactance. [*]Using a light bulb brought the readings down but didn't necessarily improve the performance in an area of track with poor performance. [*]The bench section of track which wasn't working very well, as of yesterday, had both a high resistance, 150 ohms, and a high reactive component in the same ball park. The bulbs would bring down the readings but didn't improve the performance. [*]Putting one staple back in at the two sections that had staples made the resistance readings get very low, 2 - 5 ohms, the reactive component stayed in the 40 to 70 range though. When I ran the engine around, its performance was measurably worse, with large areas of check track messages but it wasn't as bad as when I had all 18 staples installed. [/list] I also tried several combinations of bulbs. Putting two 12V bulbs in series didn't work as well as one 28V bulb Radio Shack bulbs. Putting two 28V bulbs in parallel didn't really improve anything, but the VSWR meter said it made an almost perfect 50 ohm match. From a functional perspective, one 28V Radio Shack bulb and the RC network in parallel with it seems to provide the best overall performance.

I removed the track isolators on the bench section of track that no longer works well. That made the track signal levels go down a bit on either side of the bench but now that section of track has a solid 4 or 5 reading at the minimum. Running the Hudson with one passenger car provides usable to excellent track signals all the way around the oval, which is good enough. Adding the F7 onto the track bumps up the reading more.

Putting the light bulb loads where the power supply / TIU plugs into the layout seems to provide the best performance. Performance is less if I plug it directly into the TIU.

If this level of performance can be maintained without a lot of effort, I'll be able to wait until MTH comes out with PS3 for large scale before I convert any more engines. If it goes down the tubes again, I'll convert everything over to DCC and be done with it - that is less work than fooling around with the track.

So that is the story. I need to move on to other issues, like running trains, building a couple of buildings, and working on remotely operating the switches. I also need to order some more rail clamps, I have used up every one that I had in reserve for this project.

Tom


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## Tom Bray (Jan 20, 2009)

Posted By Tom Bray on 06 Sep 2010 02:51 PM 
I tried looking at the track using the antenna analyzer but didn't really find anything that would qualify as a smoking gun. Here are some things that I found:
[*]Looking into the track from the power feed point yielded a 2:1 VSWR at 3.75MHz. I could easily load up my ham rig into it and use it as an antenna. [*]Looking from the track back to the power supply, the readings in areas that worked had resistances of 5 to 50 ohms and a reactive component in the same ball park, 5 to maybe 80 ohms. My meter won't tell me if it is capacitive reactance or and inductive reactance. [*]Using a light bulb brought the readings down but didn't necessarily improve the performance in an area of track with poor performance. [*]The bench section of track which wasn't working very well, as of yesterday, had both a high resistance, 150 ohms, and a high reactive component in the same ball park. The bulbs would bring down the readings but didn't improve the performance. [*]Putting one staple back in at the two sections that had staples made the resistance readings get very low, 2 - 5 ohms, the reactive component stayed in the 40 to 70 range though. When I ran the engine around, its performance was measurably worse, with large areas of check track messages but it wasn't as bad as when I had all 18 staples installed. [/list] I also tried several combinations of bulbs. Putting two 12V bulbs in series didn't work as well as one 28V bulb Radio Shack bulbs. Putting two 28V bulbs in parallel didn't really improve anything, but the VSWR meter said it made an almost perfect 50 ohm match. From a functional perspective, one 28V Radio Shack bulb and the RC network in parallel with it seems to provide the best overall performance.

I removed the track isolators on the bench section of track that no longer works well. That made the track signal levels go down a bit on either side of the bench but now that section of track has a solid 4 or 5 reading at the minimum. Running the Hudson with one passenger car provides usable to excellent track signals all the way around the oval, which is good enough. Adding the F7 onto the track bumps up the reading more.

Putting the light bulb loads where the power supply / TIU plugs into the layout seems to provide the best performance. Performance is less if I plug it directly into the TIU.

If this level of performance can be maintained without a lot of effort, I'll be able to wait until MTH comes out with PS3 for large scale before I convert any more engines. If it goes down the tubes again, I'll convert everything over to DCC and be done with it - that is less work than fooling around with the track.

So that is the story. I need to move on to other issues, like running trains, building a couple of buildings, and working on remotely operating the switches. I also need to order some more rail clamps, I have used up every one that I had in reserve for this project.

Tom


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## Tom Bray (Jan 20, 2009)

I see that the edit function is posting both copies again ... what a pain.


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## SteveC (Jan 2, 2008)

Tom

You didn't 'Edit' your reply you 'Quoted' it, of course it's going to post the quote and leave the original alone.


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## Greg Elmassian (Jan 3, 2008)

Tom, supposedly PSIII runs on DCC... when it comes out in LS then you can run those MTH locos reliably on your layout under DCC, and perhaps slowly convert the rest of your MTH locos to the new PSIII hardware, or just good old fashioned DCC. 

Regards, Greg


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## Tom Bray (Jan 20, 2009)

If MTH ever comes out with PSIII I will be ordering 2 upgrades and the primary controls for the railroad will become DCC. 

We were running the trains this evening and when the DCS system works correctly, it is a nice system. Although, except for the regulated speed feature, I really don't use any features of DCS that aren't available using DCC. 

Tom


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