Track voltage w/ DCS

Measure the voltage at the channel input and output, and at the tracks. They should be the same.

Thanks Barry I'll try that. What voltage should I expect to see? I thought these train sets ran at closer to 18V so that's why the 12V surprised me and made me wonder if that's part of my problem.

 

 

Are you using just the Z500 brick or do you have the controller hooked up also?  If so, no need to hook the controller up, just connect the brick right to the TIU input.

 

My Z750 brick puts out 21vac, but TMCC engines (Lionel, Atlas, 3rd Rail, ERR) say not to use more than 18vac.  I ended up getting a Lionel 180w brick (Powerhouse?) which puts out 18vac.

Bob I'm using just the Z500 brick hooked up to the TIU.

Are you using the controller that comes with the Z500?  If so, take it out of the circuit and check the result.  I assume you're using the AC voiltage setting on the multimeter.

 

The shutting down may not be DCS-related.  Are both rollers on the loco clean, and the center rail of the switches?  Is the track on all 3 legs of the switch live?

 

Here's an easy way to test the engines center rail pick ups(rollers) Park one set of rollers on a piece of paper or electrical tape.  Does the engine receive power through the other set of rollers?   repeat with the other set.

I suspect the problem may be your track as RJR suggested...jumper the 2 outside rails together with a piece of wire. This way it doesn't matter which outside rail gets the feed wire and insures good contact which can be lost around switches.

A roller spring could be weak.  Does loco stop with the same roller on the paper; that would indicate a problem with other roller.  When loco stops, are both outside rails powered or only one?  What loco is it? Reason I'm asking is to try to pin issue to hot or ground.

One of my grandsons borrowes my lococ and when I got them back they wouldn't run.  His new track had left a tough film on the rollers.  I had to sand it off.

Net,

  All these men are giving you good advise, Greg probably has the permanent fix, the problem is usually not your volatage, but the gap formed by your switch, connecting your outside rails usually eliminates the power loss as the engine moves across

the switches, giving you constant contact for powering your engine.

PCRR/Dave

 

Ok guys thanks for the help/tips. Here's what I have so far...

 

1. Right now the train seems to be making it through the 2 O-31 switches ok at say 7 smph so it seems like the issue comes & goes.

 

2. I tested the pickup rollers on a straight track using a piece of paper & the engine did not shut down on me so it would appear the pickup rollers are OK

 

3. I took a reading at the fixed 1 input and fixed 1 output and got about 14V on both and get about 12V at all points tested on the track (analog multimeter).

 

4. While I was taking voltage readings I noticed that some times certain sections of my track would not have both outside rails active as ground. Meaning I would get a voltage reading consistently when the leads where touching the center (hot) rail and the outside (ground) rail BUT sometimes the inner rail would not close the circuit and I noticed that as the train made it through a switch then suddenly that inside rail suddenly became grounded and I would get a reading on the multimeter. My power drop to the lock on is on the outside of the track so the lockon leads are connected to the center rail & outside rail and I would always get a voltage reading on the center & outside but the inside rail seems to switch around depending on where the train was in relation to the switch. Perhaps this is normal but throwing it out there in case it's a clue as to what could be happening.

 

5. Even now where the train seems to be making it through the switch at slower speeds than I was able to go at before it still sort of "stalls" a little over the switch. I can hear it kind of pause a bit and then go. This all appears to me as something related to the engine loosing power for some reason when going really slow over the switch and shutting down but it's not happening 100% of the time it seems.

 

Any advice?

Some things to consider...

 

First, RealTrax does not have any internal connection between true two outer rails, except perhaps internal to its switch tracks.

 

Second, the control rails used for automatic non derailing operation (the two outside rails that form a "V" in the curved area of each switch track) are insuated from track Common.

 

Third, there is no guarantee that a particular engine's pickup roller spacing will not cause it to be able to land all pickup rollers on center rail dead spots simultaneously, although with a single O31 switch track this is very unlikely to occur.

 

Fourth, if an engine does not have at kleast one mental, non-traction tired wheel on an outside rail that actually has Common running in it, the engine can stall, particularly if it's running very slowly at the time.

 

Netsurfr:  Let me try to explain.  If you look at your turnouts, you will see that there are two portions of the outside rail that are insulated from the adjoining sections of outside rail.  These are to work the non-derailing feature of the turnouts.  However, this also prevents ground circuit from passing those insulated sections.  As a result, it is possible to have sections of track where only one outside rail is actually grounded.  If you have to turnouts in a certain pattern, it is possible that ground cannot get past those turnouts at all.  It is also possible that a locomotive for some reason is unable to get ground when passing through these areas.  That is why I asked what logo you have; so I could try to determine if that is a problem with this locomotive.

Take your multimeter, and put one lead on the center rail and the of the lead on an outside rail next to it then slide the tool along through the turnout and see if you get power all the way.  Then try it again with the one lead on the other outside rail.

The way you describe the problem, I really think that the problem is in the track work rather than the locomotive.  Can you post a sketch of the area?

 

at the location where you get no voltage reading do you get a reading if you move the probe that is touching the outside rail to the other outside rail directly across the track?

 

Also, without moving the probe on the outsiderail, do you get a reading if you move the center rail probe to a location some inches away?

 

Does problem happen on both turnouts?

 

Have you carefully cleaned the center rail of the turnout, with alcohol or CRC electronic cleaner or equivalent?  

 

Ok, so now we know there is no center rail problem on track.  If you stop loco where it's dead, take a jumper wire and reach from sides to connect the 2 outside rails.  Loco get power?  If yes, check loco drive wheels to make sure they're clear.

 

Anyone else with that loco:  is there any contact shoe toiching drivers to assure good ground?

 

On some locos, you can slip a thin probe under neath and jiggle the rollers, or with the other end of the probe connected to power, see if the loco will run.

 

I suggest you post the model number of the loco and of the switches.  There must be someone on the forum with the same loco and the same brand & model of switch, who is willing to aedvise if he/she has a problem.

Well the train has now been making it over the 2 switches while traveling at 5 smph  w/o powering down since Sunday night so not sure what to make of this. I'm calling MTH to hear what their techs say. I have no specific part number for the locomotive because it's part of an RTR set. I did post the MTH part number to that set on an earlier post here. I know someone else on this forum who has the same set & engine & O-31 switch and he has no issues. He said he did when he first bought the switch and his local train store owner told him that you have to make sure the track coming off the switch Y end can make the switch act up/short if they have too much angle or something like that.

Cut and pasted from initial post:

 

"....Fixed 1 output to the track (only one power drop to track via a lockon)."

 

Is this still the case, only one power feed to the entire track plan?

 

Tom Tee: That would be true only for the smallest layouts.  As layout gets larger, one encounters power loss in long lengths of track, so multiple feeds are needed.  However, when that occurs, one should break the layout into blocks by having gaps in the center rail (absence of a pin or using a fiber pin), with each block having no more than one hot feed. This is to prevent a loco from getting multiple DCS signals.  There should also be multiple ground feeds to the outside rail, to aid power dstribution, but unlike center rails, outside rails should not be insulated between blocks.

netsurfr:  If your loco doesn't slow down at far ends of layout most distant from lockon (a sign of power loss having nothing to do with DCS), and still responds to DCS commands, I wouldn't change a thing.

Loco operates fine at the furthest points of the track and I get consistent voltage readings there too. Only issue I have is going over the switches at very slow speeds and it's been working fine the last day or so. I left the train (along w lighted passenger cars) running at 5 SMPH and walked away for about 30 minutes yesterday and when I came back it was still running. A couple of days ago it was stalling at the switches at much faster speeds. Perhaps a combination of cleaning train, track & moving it around improved things. Still planning on calling MTH though since all this is new/under warranty.

 

RJR, I basicly agree with all things being perfect.  However, my world is very imperfect.

No matter what size any layout is, my approach is to supply power on all sides of all turnouts and crossings. In three rail, I additionally run a bonding jumper at all points of feeds connecting the outside rails on plastic/wood ties unless isolation is desired for other purposes.

IME, I have found three rail to be more sensitive to needing redundant power feds than two rail.

Not really needed all the time but I have never had a power supply problem or a signal problem.

To me, that track plan just screams a minimum of three feeds.  One between the turnouts and one in each loop.

Ok I have now been running the train around the track at 5 smph and have not had another engine shutdown so not sure what to make of it but I think I'll leave it alone & hope the problem went away!

Tom Tee:  I do not disagree with you.  I understood your question as relating to your layout.  If a layout works well, I would leave it as is.  If I were designing netsurfr's lsyout from scratch, I would have 5 blocks, two in each loop and one between switches.  Each would be fed thru a toggle switvh.

 

On my layout, each turnout is the end of 3 blocks.  All 70+ blockd have toggle switches.

RJR, Nice, that is exactly what I do with each benchwork job on which I install and wire track.

 

www.curvedbenchwork.net

Tom Tee:  Nice looking benchwork on your link.  Interesting grain on some of the wood' what type is it?

Thank you,  Baltic Birch / Russian plywood w/ solid core layers. 

 

I hate to depart from the thread topic, but I would guess that the plywood you use is more expensive than fir plywood.  Is there a reason you use it?

netsurfr;

I suspect your engine is simply loosening up from new part break in. Thus it will coast far enough to get across the dead spots now.

Now, there is a possible simple fix, Look at the Rollers and see if they can be reversed in facing, this will alter the spacing and may allow power pickup through the switches.

Be aware it may also make it worse, depends on engine and switch in combination.

Note that different curve dia. switches have different spacing needs.

 

Good Luck !

 

RJR, Price very close, Quality does not have to be expensive. 

 

In fairness to this DCS thread please contact me direct to continue plywood thought.  (address under forum member's information.)

 

Or possibly switch this line of conversation over to the layout construction forum.