Curious: Approximately what is the maximum footage of track that any ONE DCS channel could support at any one time?
Original Post
Replies sorted oldest to newest
John,
Approximately what is the maximum footage of track that any ONE DCS channel could support at any one time?
There's no exact answer due to a variety of factors. However, for TIU's prior to the Rev. L, I'd estimate 200-250 feet per channel. The Rev. L can possibly increase that to 350-500 feet per channel.
Your mileage may vary.
Thank you Barry. I have an "interesting" situation develop. With NO changes to anything, my PS2 engines are receiving a very POOR signal in certain areas. A PS3 engine in the same spot: "10s".
I can't figure out why as the layout had worked flawlessly for the past year and then all of a sudden, this issue began, again with no changes.
I've worked on a resolution for about six hours now--swapping wires--turn off Blocks--checking transformer and TIU power. It's going to be real interesting to figure out what is going on, unless of course it fixes itself the next time we power the layout.
Thank you again.
Sounds like maybe a TIU problem on one channel. Can you try a different channel, or swap in a different TIU?
Rod
John C. posted:I can't figure out why as the layout had worked flawlessly for the past year and then all of a sudden, this issue began, again with no changes.
I've worked on a resolution for about six hours now--swapping wires--turn off Blocks--checking transformer and TIU power. It's going to be real interesting to figure out what is going on, unless of course it fixes itself the next time we power the layout.
Thank you again.
Rod Stewart posted:Sounds like maybe a TIU problem on one channel. Can you try a different channel, or swap in a different TIU?
Rod
If you have not touched anything on the layout I would have attempted Rod's solution before swapping wires or any other changes. Does it occur with just the suspect engines on the track themselves?
John,
With NO changes to anything, my PS2 engines are receiving a very POOR signal in certain areas.
Obviously, something has changed. 
You're approaching the problem correctly. Eventually, you'll nail down the culprit. Been there. done that, got the T-shirt!
Rod and BobbyD: Thank you. I did. No luck. I'm going to start, from the transformer, and test, each and every wire. Fortunately, I have a friend who will assist me. I will write back what we discovered. I'm guessing the response will come in about 2 to 3 years. :-)
Barry: You are right. I did something and I can't wait to figure out what it is. I swear I changed absolutely nothing. We noticed it during an operating session and I initially believed it was the engine. It was not. It is ANY PS2 engine.
This is the second time I've observed first-hand that the PS3 technology is superior to prior technology by far. My PS3s are "10s" everywhere.
+As I mentioned we , re running 4 tiu in super.... Any loose connection can be a problem. We have about 100 feet per channel. I'm sure we could get a little more track signal wise but it just so much easier than messing around with light bulbs etc... we have 1 bulb at each terminal block.
Don't forget each channel has it's own signal generator so take advantage of it, use the same power if you want.
I 'm still a little confused on what your original problem was... It shouldn't have been a problem the way you had things hooked up.
Apparently proto-3 doesn't care which feeder goes to the center rail unlike proto-2.
Gregg:
I liked your comment: "Don't forget each channel has it's own signal generator so take advantage of it, use the same power if you want."
If nothing else works, I may do that. However, I want to discover why the system that has worked perfectly for the past year, decided to stop working.
Quick question, clean track?
Have you read through this thread from a couple of weeks back? Might help, might not.
BobbyD: Yes very clean.
MRMOE50: Interesting read. More to think about.
Barry: I'm 50 miles from home and can't wait to get there to test a new theory!
FROM ANOTHER THREAD ON THIS FORUM: DCS SIGNAL ISSUES, In part...
I work at an aerospace company, and have an RF expert as a co-worker who also is an O gauge railroader. He explained to me how the digital signal riding the wires is radiating outward, and if the positive and negative sides of the signal are parallel to each other, they reflect against each other, with one slightly out of phase with the other. The difference in the signal polarity gets further and further out of phase until eventually, they will cancel each other out for a short period of time, causing an attenuation or weakness in the signal.
BINGO!!! I bundled my wires tightly so that they wouldn't be torn down by moving storage items either out from or under to the layout. I wonder if this would be it, but as soon as I read this I remembered zip-tieing a bunch of wires.
I'm guessing that this is my problem. We will see.
John,
I'm guessing that this is my problem. We will see.
I'd take the other side of that bet.
That kind of a problem doesn't just one day "happen". Further, my wires are bundled tightly together with no ill effects, going on 12+ years.
Interesting topic..i know i am staying tuned
My experience is that when there is a sudden dimunition in signal, a wire connection is failing or there is a track whose pins have loosened. The former can be a bear to find. Start by checking the connections at the TIU.
Try removing the cover on your TIU and check to make sure all the nuts are still tight, that secure the input and output posts. That's one thing that can change over time.
I pulled my TIU once to take upstairs for an upgrade. I put it back on the layout and it acted up. It took some time because I just couldn't see it. One channel had the black and red wires switched at the inputs. I have inline fuses there and somehow they hid the problem. I couldn't figure out why the system acted up so much?
Some times it's just plainly there to see.
Another time it was my Lionel tank cars w/ sounds which usually aren't an issue. Switching stuff around I put a new outside main on a single TIU channel. The inside main has two TIU channels and a third for the sidings. That one can handle a little more interference than the new outside main with one channel. Simply putting some extra tank cars on that track to please the grandson, caused much more grief, than it should have.
Barry: I "undid" my tightly bundled wires. This did managed to ever so slightly raise the signal, but it was/is still terrible.
Tonight, I begin the fun task of "un-wiring" the layout. Of course, I could just throw the PS2 engines in the trash along with the conventional engines. Problem solved! 10s all the way around! :-)
What I am going to do is this: I will test each side of my Z4000 through each of the four ports on my TIU onto my one single strip of programming track. The purpose will be to verify that the transformer (both sides) and all four ports of the TIU are able to put a signal of "10" onto the one piece of track being tested by a PS2 engine. I will also test this with more than 1 PS2 engine. If successful....
My layout is wired as follows: from the transformer, to the TIU, to MTH power distribution boards (one board is for one side (I call it the "A" side) and the other board of course my "B" side. One wire each from each board goes to an Atlas Selector (SPDT toggle--in Atlas case a sliding switch). Of course the "A" side goes to the "A" input of the Selector and "B" goes into the lower input of the same Selector. Then a single wire (there are four outputs) goes from one out to an electrically isolated section of track--a "Block." This is a very easy system.
I will first mark and then disconnect EVERY SINGLE WIRE from my two power distribution boards--effectively "killing" the entire layout. I will then reconnect one single wire at a time, and one block at a time test the signal strength of a PS2 engine. After 1 Block is successful, I will do the same to the next, and if successful retest the first Block to ensure it still works.
I have more than 50 Blocks. Wish me luck in discovering the issue is not on the 50th+ Block. My back already hurts just thinking about this.
I wouldn't unwire the layout. Rather, I would start at the transformer end of the wiring and work downstream, shaking each wire to visually see if there is a loose connection. If the problem is all over the layout, I'd concentrate on wires that serve the entire layout, including ground circuits.
RJR posted:I wouldn't unwire the layout. Rather, I would start at the transformer end of the wiring and work downstream, shaking each wire to visually see if there is a loose connection. If the problem is all over the layout, I'd concentrate on wires that serve the entire layout, including ground circuits.
Great idea. After checking that it isn't a TIU issues go the "least destructive" route! He said nothing was changed or added wiring wise so that should really narrow it down fast.
John,
Just follow these steps from pages 152-153 of The DCS Companion 3rd Edition:
Methodical Approach
The methodical approach makes no assumptions regarding what may be causing the problem. Using this approach, everything is suspect until proven otherwise. A process of elimination is utilized in a step-by-step procedure that works to reduce the number of possible causes of the problem until the culprit is found.
The first step is to rule out DCS component failures. This is most easily accomplished by temporarily replacing the DCS components with known, good ones. However, not everyone has the luxury of having an extra DCS Remote, TIU or AIU available. In this case, it may be possible to bring the questionable components to another layout at a friend's home or a hobby shop to test them there. It's also easy to simply swap TIU channels and see if the problem moves to the other channel or stays on the original channel. Either one tells the operator something new about the problem and can narrow down the issues.
The DCS Companion
The next step is to rule out problems with individual DCS engines by attempting to duplicate the problem using a different engine. If the problem persists, it's unlikely that a DCS engine is the source of the problem.
The third step is to eliminate wiring problems. This can be time consuming, however, if a logical process is used this will nearly always isolate the problem. The procedure is to work outwards, starting at the transformer. Check to ensure that the transformer is putting out the expected voltage. An inexpensive multimeter can be a big help in troubleshooting wiring problems. If one is not available, an 18 volt bulb in a holder connected to a pair of wires can be used to indicate if voltage is present. Measure the voltage at the TIU's channel's input terminals and then at the output terminals. Look for a blown fuse inside the TIU or in an external fuse holder.
Continue checking the voltage at the entry to the terminal block and at the exit point where the terminal block is connected to the tracks. Then check to see if voltage, and the DCS signal, is leaking between blocks that should have their center rails isolated.
Substitute transformers, DCS components, TIU channels, and wires wherever possible. At some point the cause of the problem will be discovered.
 | This and a whole lot more is all in “The DCS Companion 3rd Edition!" This book is available from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at OGR’s web store! |
will first mark and then disconnect EVERY SINGLE WIRE from my two power distribution boards--effectively "killing" the entire layout. I will then reconnect one single wire at a time, and one block at a time test the signal strength of a PS2 engine. After 1 Block is successful, I will do the same to the next, and if successful retest the first Block to ensure it still works.
I have more than 50 Blocks. Wish me luck in discovering the issue is not on the 50th+ Block. My back already hurts just thinking about this.
GOOD LUCK.... I might test the signal on each channel's track first before disconnecting everything... If you find a low signal then disconnect everything on that channel and start adding the feeders back...
I know it can get frustrating at times... Sometimes longer blocks get a better signal that say 2 or 3 of the same length of total track.
Ex one 30 foot block can get a better signal than 3 ten foot blocks.
I believe I have a TIU issue. On my test track, all outputs gave me a "10" with PS2 engines. However, around the layout at various places, I can only get "4" and "5" signals but when I flip my SPDT switch to "trade" which transformer powers that Block the signal will jump to "10." Tomorrow I will switch wires from one side of the transformer to the other, if the low range signal and perfect signal switch sides of the transformer I will have my verification.
I will also switch out my TIU for a virtually brand new TIU to check for differences.
UPDATE: After 3 hours of working on it last night, and after 4 more hours from 6 AM to 10 AM this morning (Eastern time Wednesday), I am down to the brass tacks and am totally and completely bewildered.
The only wires I have coming from MTH Z4000 are the two positive ones. I unplugged the others. There is NO NEGATIVE.
I unplugged all other transformers. I unhooked ALL WIRES at my MTH Power Distribution Boards.
The two wires from my MTH Z4000 run to the input fixeds channel, 1 each side.
The two output wires going directly to an Atlas Selector. One wire goes to the top input. The other the bottom.
The four outputs have 1 wire each going to a separate isolated Block of track. I have traced and retraced the wires six or seven times.
When I have the Selector Sliding Switches all either up, or all down, there is NO short circuit. HOWEVER, when I move any one of these sliding switches to the opposite position, a short is created.
You can see the digital screen on the Z4000 and when moving one handle, either one, the BOTH DISPLAYS will move together, meaning a short.
I do NOT understand how there can be a short circuit when there is NO NEGATIVE to the layout. All wires unhooked and the only powered plugged in transformer is the Z4000.
I did test the: transformer, TIU and Selector. In fact, I "replaced" the TIU with a like-new TIU and changed out the Selector. Same result.
I hooked up the MTH Z4000 to the TIU and the TIU to a piece of complete separate Programming Track that is not connected to the layout. Everything worked perfectly!!!
Somewhere, somehow, someway, a negative charge must be getting to the layout! But, how???
I've got an electrician friend of mine on the way over later this afternoon. It is going to be real interesting to determine the source of my issue. More perplexing, less the signal loss, the track did work, and PS3s worked PERFECTLY. Now that I unwired EVERYTHING less one small section, I am facing my most perplexing electrical issue ever. It has never taken me more than about twenty minutes to figure it out before. I'm on about 10 hours.
I can't wait to share the answer with the interested parties.
What a day! Wow! I spend the better part of 12 hours unwiring, brain-storming and hassling with the wiring. I learned several things including you really can’t trust the “reading” track signal of a PS2 engine. Several PS2 engines will produce multiple results in the same exact set of circumstances. Without a doubt, the PS3 technology is HIGHLY SIGNIFICANTLY better than PS2. This has been experienced directly by me.
I guess the best rule-of-thumb is to forget the track signal reading and just be happy if your engine responds. If the engine operates correctly and efficiently, what’s the difference if the signal is 1 or 10 according to that particular engine.
Lastly, if anyone can explain to me how changing a transformer’s power to a track across a big basement basement can affect the track signal significantly on the other side of the room please explain it to me. Literally electrically isolated and twenty to thirty feet away changing a block on the north wall to transformer “A” results in the “B” transformer track signal to double in a Block on the opposite side of the basement. Figure that out.
Okay, enough fun for the day! Model railroading is fun! Remember? I knew it was time to quit when my wife, Connie, came down and said: “I miss you. Are you coming upstairs?” 12 hours is enough for one day. Thank goodness my friend Gregg Burks spent 5 hours here or I may have still been down there. Tomorrow there are a mass of wires to re-install to their semi-permanent position versus strung across the floor or tracks.
I also get to put back my original hardware that all checked out fine. Everything works. PS2 engines report a wide variety of signals under the exact same set of conditions. Crazy!
Attachments
Images (2)
First, A DCS Signal strength test does test layout and the specific engine too. Either with an issue can be the problem. There are plenty of PS-3 engines that have read low until wire bundle inside engine repositioned. You never stated how many engines we are talking about, nor what the "low" number was? 4 or 8?
Besides wiring, what accessories and type of track items do you have on the layout? Uncouplers, switches etc. Accessory and or switch may have had a failure degrading signal in that area. Isolate were the signal is bad and go from there, but if a PS-3 pass through with 10s, what is the PS-2 giving? Are the PS-2 engine which are clearly older, have clean wheels, good pickp rollers etc.... G
