Legacy Signal

The remote "talks to the base.  The base then sends the signal to the track and earth  ground radiator, the engine receives the signal from the track and earth ground radiator.

The SC2 receives it signal the same way as the engine.

There is a good discussion on the signal if you want to get into the nitty gritty somewhere in this section.

See  http://www.trainfacts.com/trainfacts/?p=317 for a more detailed explanation.

Great easy to understand explanation Dale! You could be the honorary TMCC/Legacy ambassador, well except for the whole book thing. Seriously though, your knowledge and understanding of the system, and patience with those of us that do not fully understand, is greatly appreciated.

I just wish that Lionel was carrying this ball (correctly), rather than the poor technical support we have had from them so far.  I am glad to offer a glimmer of light to make this easier to deal with.

I use the wall warts to power the SC-2.  How does the U ground get there so the SC-s communicates properly?

Ken

Dale,

I agree 100% with Rick - excellent explanation with enough details to satisfy everyone.

Thank You!

Alex

That is a very good question, Ken.  I don't have an SC-2, and I am not too confident that I know the answer.

It could be completely opposite of the path for a locomotive.  The wallwart has the earth ground signal on the primary winding, and that signal can be capacitively coupled to the secondary winding.  The signal would then flow down the power cable and into the ground side of the power supply.

The SC-2 has an antenna, but in this case the antenna may be picking up the track signal rather than the earth ground signal.  The receiver really doesn't care about which signal get to what ends of the antenna and ground inputs - it just operates on the difference in voltage between the two ends.

Does anyone have an SC-2 that they would care to lend me for experimenting to determine the true answer?

Dale,

You want one, in the intrest of furthering our knowledge, you got it. Where do you want it sent. Post here or send to my listed email.

Al

I tried to use my wallwart with the SC-2, and it didn't work until I ran a track common to the ground terminal of the SC-2.  I'm 99 and 44/100% sure that it works exactly like a locomotive as far as reception.   I believe the SC-1 also works this way.

From the SC-1 Manual

Connect the SC-1 common lead (center row) to the U terminal on your accessory power source. Next, connect the power lead from the accessory to the A (power) output on the transformer.

Hard to believe they did something totally different in the SC-2.  It has an identical antenna to the SC-1, and as I noted, I had problems when the common lead was disconnected from the SC-2.

I think that's why I had so much trouble with the SC-2 when I first wired it up. I disconnected the position #1 from the com terminal so I could use it with a  Fastrack switch. Then I used the wall warts for power. The operation was intermittant and when it worked, it worked poorly. Then for reasons I can't recall, I switched to using a CW80 with the com terminals connected to the track com terminal. This makes sense to me now. It was emphasized that the com terminal needed to be connected to the base (for signal transmision but didn't put it that way) on page 6 in the manual, but I missed that and didn't think it through.

Anyway, the SC-2s work great now.

John, if you have been inside both the SC-1 and SC-2, maybe you can tell me if the Triacs in the SC-1 are floating or isolated from the output terminals to the turnouts.  My thought is that the relays in the SC-2 provide full isolation of the switched terminals from the power supply (and the wall wart), but I would expect that the SC-1 doesn't have such complete isolation.  And maybe that trace on Unit #1 needs to be cut to achieve the full isolation that would be required for the "inverted" operating mode I hypothesized.

The SC-1 triacs are not floating, and they don't work with Fastrack switches.   I'm not sure if the triacs could easily be isolated without optical coupling, since you need to have them connected to the receiver circuitry to fire the triacs. Other than opening a couple up to put in replacement triacs, I didn't do much tracing of circuitry, I was on a single mission at that time.

If I get a chance, I'll open one up again and do some measurements.  I just assumed that given the nature of the switching, they would have a common ground.

I use fastrack switches w/the SC-2 & I have cut the ribbon.  Where would I connect the common from the transformer to improve reception to the SC-2

Ken

The common terminal is the one on the top of the 2 terminal connector...just below where you cut the ribbon.

I tied the common terminal of the SC-2 to the common of the transformers.  On the two SC-2 that the ribbon is cut on & used for track switches the first switch of each SC-2 chatters.  On the third SC-2 that is used for accessories only the first position works fine.

Ken

I have two SC-2's connected to Fastrack switches here, both of them have a switch connected to position 1 with no issues.  I've never seen position 1 do anything out of the ordinary, works just like the others.

I cut the ground lead, and I'm powering the SC-2 from the track, so I just connected to a track section close to the SC-2 with the power leads.  Make sure you check the continuity of the cut in the ground lead to insure it's really cut.

I am using a wall wart & the ribbon is cut.  

Ken

You should give track power a try, and make sure the outer rail is connected to the top terminal of the power connection.  Several people have stated they had issues using the wall wart for power.

When the ribbon is cut you can not hook anything to the aux port

Ken

When the ribbon is cut, the ribbon showing just above the com terminal of the aux, you are cutting the first position loose from the aux. the aux may still be used as the power input. If i were to guess, the wall wart might be out of sync with your tracksignal...just a guess, but why not try track power?

Well, that's news to my SC-2's, they have track power coming in on the aux-power connection.  They're also working 100%, so I'd say you're incorrect here.

On the subject of SC-2s, I want to mention something that happened today. I have three SC-2 boxes, attached in different places to the bottom of my 1/2" plywood layout base (with 2" of blue foam on top). There's of course track directly above each of the boxes, on top of the foam. One of them works perfectly in that configuration.

Let me also mention that I'm powering the box from 16v power from the transformer, with the Common wire the same as attached to the track.

In hooking up the second box, it wasn't receiving commands (the red light didn't blink) from my CAB-2. Finally, in desperation, I remembered that the SC-2 takes radio signals from the track, and when people have had signal problems, there's been talk of "ground plane" wires to clarify the radio signals. So I ran a wire from the earth ground on my 110v power up and under the SC-2 box. Now it receives signals fine.

This should be mentioned in the troubleshooting pages in the SC-2 manual. I bet others are having this problem and might not happen across this solution.

Now to hook up the third box. I'm sure additional "lessons learned" await...

   Bob A.

Yep, my SC-2 went from about 10% reliability to 100% when I wrapped an earth ground wire around it.

Instead of going form the outlet, you can also tap into the earth ground from pin 5 of the command base serial port. This is the "COM" wire if you are connecting wired controllers like the ASC to the command base.