Insulated Outer Rail and Relay for Block Signal Causing Legacy Sounds to Stop - The Rest of the Story

There is indeed no such thing, but I don't think that your situation is all that odd.

It looks to me like the Shay has poor electrical contact, in the isolated section, with the outside rail that isn't isolated.  Are you sure that this rail has a good connection back to the transformer or powerhouse, and is clean?  It certainly seems to conduct DC well enough since it appears that your signal relays switch properly when the Shay enters the isolated section, but maybe it's not good enough for the AC that powers the sound?

Are the wheels clean?

I'd also try putting a battery in the Shay (I realize though that it may not fit because of close clearances inside)?  It's used when in  conventional mode in order to tide the sound over during power dropouts.  It should work here too.

Mike

There was a topic a few years ago about adding a 0.1yF 50V Ceramic Capacitor across the gap of the insulated out rail.  This is to help maintain the TMCC signal on the insulated section.  I guess it would work with Legacy.

I have some .1yF 100v capacitors.  Would one of those maybe work?

And I will check for dirty track/wheels, but I cleaned the track recently and it runs fine and the DC does clearly get through.  I may try reversing direction of the locomotive to see if there is something to the wheel / axle conductivity issue.

I appreciate the help!

@Burl posted:

I have some .1yF 100v capacitors.  Would one of those maybe work?

No idea.  Maybe one of those involved in the discussion back then will chime in.

The caps you have would be suitable.  Also, you could use something that has a lower inrush current and no inductor directly connected to the rails.  The relay coil making and breaking may be the source of the transient that is tripping the sound.  One such design is my Insulated Track Signal Driver, Rev. 2 that is sold through Henning's Trains, it has inrush protection and DCS isolation as part of the design.  You might consider doing something like this for the relays, or even buying my product.

As for a battery, I have that covered as well.  Since it's a PITA to keep taking stuff apart to put in an Alkaline battery, not to mention the leak possibility, try the YLB - RailSounds Battery Replacement for a once-and-done battery installation.

Burl,

I do a similar approach to what you are doing but using low current DC 12 volt relay. The + end of the supply goes to one relay terminal, the other terminal goes to one insulated outer rail. The - end of the supply goes to track common.

Absolutely no problem with older Railsounds using a battery (BCR) or newer Legacy engines.

No other components are needed unless the signal specifically requires a capacitor (like a 3 position red-yellow-green signal).

Bruce

Bruce, yes, that's exactly how I have my layout wired for the block control lights, and also for crossing gate activation.  No issues ever with anything until I ran this shay.  It only does it on one block, and doesn't matter which direction it's ran or in what direction it's facing.  I have determined it doesn't happen just randomly.  It loses sound as the locomotive clears the insulated rails and the relay disconnects.  I've swapped relays thinking it might be something odd in the the coil providing feedback, but same result.

I thought I had the capacitors, but if I do, I can't find them.  But, as I think about it, it isn't that their isn't TMCC signal in the insulated rail.  All other functions still work.  It just loses sound when the locomotive exits this one block and the relay opens again.

Any ideas for further troubleshooting?

I don't think people realize how many 3 rail engines actually have bad/limited ground pickup. Consider it's wearing nice rubber insulators (traction tires) on two or more wheels and then cut the ground pickup in half with an insulated rail and you might get the idea. Try parking a boxcar in the insulated section to see if your engine can enter into the section without conking out. Your engine may appreciate using the boxcars axles as a bridge across the outer rails (two rails will always be better than one for ground). I had this happen with a couple engines as I was installing my signals a few years ago. It at least gave me a clue as what to chase as opposed to scrubbing my rollers two or three times.

John, I just scrolled up and saw your post, and it was very timely!

After digging through drawers, I found the capacitors and after reading your post they would be ok to use, I put one over the insulator between outer rail sections to give it a try.  Much to my surprise, that fixed it!  I've made 10 laps around the layout, not a single loss of sound.  I did learn before that it was only happening as the locomotive was exiting the insulating block, so as you say, I think the coil was creating a "transient" as electricity was removed from it.  Sometimes I think I should have chosen the EE (Electrical Engineering) major instead of mathematics.  I can't say it would have helped any in my professional life, but it sure would have been useful in this hobby nowadays!

I really appreciate everyone's help with this, and so many other topics!

Bruce Brown:

Can you tell us what software you used to draw the circuit you posted? Thank you!

@Arthur P. Bloom posted:

Can you tell us what software you used to draw the circuit you posted? Thank you!

Arthur,

It is free software from Digi-Key called Scheme-It.

https://www.digikey.com/schemeit/home/

https://www.digikey.com/schemeit/project/

I have changed the topic title to indicate I've learned more.  While the insulated block triggered the engine's behavior, I do not think it was the root cause of the problem.

I had been running it on my outer loop, and decided to run on the inner loop, which has more insulated blocks.  I observed the same behavior on another insulated block, so just put another capacitor.  This time, it did not fix the problem.  But, on my outer loop, the block in question was mostly in a tunnel, on the inner loop it was used to trigger a crossing gate where I had a clear view.  I noticed sparking from the drive shafts and the frame!  This seemed very odd to me indeed!

So, I was planning on swapping out a bad coupler anyway, and just went ahead and disassembled the locomotive to start that process and hunt for a short.  What I found was two sets of wires that were pinched, not enough to visibly break the insulation, but evidently enough that there was conductivity as the locomotive passed the insulated block and the drive shaft side became a required route for the electricity to reach the insulated outer rail.  It took nearly two hours with a multi-meter and testing to find the problem since a visual inspection of the wires only showed them being mashed, but no insulation break.  I don't understand why a capacitor countered the problem on the outer loop's insulated block though.

I also made the "fix" to the O31 problem with these engines shown here, and am very pleased now with how it runs throughout my layout.

https://ogrforum.ogaugerr.com/topic/lionel-2-truck-shay-031-solution

I hope this may help someone else who discovers a similar set of symptoms.  Thanks again for everyone's help!

Like I said, your engine had a bad ground.

Bruce, thank you for the links.

@Burl posted:

  I don't understand why a capacitor countered the problem on the outer loop's insulated block though.

If the problem was happening in other places it is questionable if the first capacitor really did anything to fix the issue. It seems more likely the bad ground Norm points out was/is intermittent.

A further update and some clarity.  After running the engine this morning several laps to fine tune the "O31 fix" with a little more dremel work, I found it does on occasion lose sound on the inner loop insulated block.  I had removed that capacitor, but decided to replace it.  Problem gone.

So, I think I had a dual issue going on.  One with the signal, and another with the short.  The capacitors seem to have fixed the signal issue.  On the short, to be clear, their was no lack of ground if the definition of ground means connectivity to the common run through the outer rail.  In fact, if this were the case, I don't think I would have observed the sparking.  The issue was a short through insulation on a "+" wire in the locomotive that had been pinched very thin and evidently had a hole too small to see, but large enough to allow electricity to flow with adequate voltage and a strong path to the ground.

Again, thanks to everyone for the help, and I help this post will help someone else with similar problems.