I've got a modern Lionel Hellgate bridge on my fastrack layout. When my engines get about mid-way through the bridge they loose the TMCC signal and stall. Strange thing is this only happens when I have the bridge lights powered. If I disconnect the lights all is fine. I'm using a modern ZW for power. If the bridge lights are powered with track power the engines really die, and the only way to get moving again is to disconnect the lights. I also tried powering the bridge with one of the accessory outputs on the ZW, and in this case, the engine stalls slightly, but I can usually get it through the bridge by increasing the engine speed. I'd much rather power the bridge lights with track power as it's easier to jumper from the track to the bridge, rather than running power from an accessory transformer output.

Any thoughts on what I might do to be able to power the lights with track power and cure the signal problem?

Matt

Please check past threads regarding earth ground and TMCC signals. The bottom line is that Metal Bridges, close parallel tracks, and overhead tracks and confuse the engine reception of the TMCC signal. Running a wire from a water pipe under the track (or over as a pseudo telephone line etc.) can eliminate the engine signal confusion. If the lights blink, or the engine also runs when you place your hand over the engine, that is the issue. I have a Legacy SD 40-2 that just started to exibit that behavior after 6 months of running. Connecting the wires I ran between the homosote and the plywood on the 2nd level, permitted the engine to exibit normal behavior (stopped stopping and blinking its lights.)

Thanks. I did try connecting a grounding wire from the 3rd prong of the power strip where the ZW is plugged in to the bridge itself. Thought this would have the same effect, but guess not as it didn't seem to help. I'll try running a wire right under the track next.

Matt

I'm not sure how the track is mounted to the steel frame of the bridge, but if it directly sits on the bridge it will need to be isolated from it. I use small pieces of electrical tape under the metal ties on other metal bridge structures and it helps a lot. If you are grounding the bridge and the ties are on the bridge metal you are effectively grounding the signal.

Using Fastrack, so pretty sure the plastic roadbed keeps the rails from touching the bridge (just lays on top of bridge), but I'll double check this.

If you are using Fast Track this is probably not the issue. Is there any lighting in the HG bridge? If so does this power originate from a transformer that is part of the track supply? By grounding the bridge you could be inadvertently grounding the TMCC signal.

Your house wiring may not be true with the ground prong (3rd). Many houses do not have that plug properly grounded. If your hand over the unit effects the lights blinking that might be the case.

Try lighting the bridge from a seperate power source... one that isn't connected to the layout in any way. If you have a small accessory transformer or one from a starter set that will do fine.
The problem comes when you hook the bridge into the layout ground it screws everything up.

quote:

Originally posted by MartyE:
If you are using Fast Track this is probably not the issue. Is there any lighting in the HG bridge? If so does this power originate from a transformer that is part of the track supply? By grounding the bridge you could be inadvertently grounding the TMCC signal.

Yes, there is lighting in the bridge, and it's only when the lights are connected that I have the issue. If I disconnect all if fine.

I'm using a modern Lionel ZW, with 2 180W bricks. 1 brick powers outputs A & B, and the other powers outputs C & D. The track I'm testing on is powered by A. If I power the bridge also with A, the engine dies in the middle of the bridge. If I power with C, the engine still seems to suffer some signal loss, but not as bad (slight stall/light blinking in bridge, but can get through by increasing engine speed).

I'll try powering the bridge from a totally separate transformer as RD suggests to see if that clears up the problem. Would like to avoid doing this on a permanent basis though as will be a pain to have another transformer just to power the bridge.

Pretty sure I'm not grounding the TMCC signal, as when I tried this still just had problems within the bridge, TMCC worked fine elsewhere.

quote:

Originally posted by winrose46:
Your house wiring may not be true with the ground prong (3rd). Many houses do not have that plug properly grounded. If your hand over the unit effects the lights blinking that might be the case.

Pretty sure my house wiring is ok, as all outlets test ok with an outlet tester (no open grounds indicated). My house is wired such that the conduit actually provides the path back to earth ground at the box. I'll try the hand over the engine test later tonight though.

Thanks for all the suggestions so far,

Matt

If you power the bridge from the ZW and then ground the metal chassis of the bridge, you are grounding out the TMCC signal as the ZW's commons are all tied together. I think the only way to fix this is to power the bridge from a source other than the ZW and DO NOT connect the commons of the ZW to the power source for the bridge. You can use the bridge power supply then to feed other light and such on the layout if need be so it's not a waste.

quote:

Originally posted by MartyE:
If you power the bridge from the ZW and then ground the metal chassis of the bridge, you are grounding out the TMCC signal as the ZW's commons are all tied together. ...

Marty, wouldn't this kill the TMCC signal everywhere?

It certainly won't help it.

Adding to others' comments and advice, I strongly suggest two solutions:

First, ground plane wires for strengthening the TMCC/Legacy signal must be wired to a TRUE EARTH GROUND. This cannot be the common post on a transformer, and in most houses (despite your explanation), the ground plug on your electrical outlets won't suffice, either. We also found that even wiring directly to a water pipe is not always sufficient. If you are able to do it, going to a true earth ground outside the house is the optimal and certain solution.

Second, try suspending the ground wire above the track (not adjacent to it on the bridge floor). The ground plane wire does not need to be naked copper; a shielded small gauge wire will do. Make sure the wire does not come in contact with the bridge.

On my layout, the Duckunder Terminal Railway, the above actions were effective in eliminating poor TMCC/Legacy signals. George Lasley and I are preparing a new article on how to optimize ground planes for Legacy.

Hope this helps. Please let us know the results on your layout if you try these solutions.

Here's what I tried. As many of you know, Lionel's modern Hellgate bridge is all metal and looks like:



First of all, powering the bridge with a separate transformer, that's not connected to my track at all clears up the problem. This is probably what I'll end up doing (will likely use an old CW-80). Was hoping I could use one of the accessory outputs of the ZW, but as Marty noted, since the ZW's commons are all tied together, this doesn't work.

As far as running a ground plane wire, here's what I tried. Referencing the picture above, I first ran a wire (used shielded solid 12 gauge wire, connected to a cold water pipe) around the base of the bridge (blue line). Was hoping to be able to run the wire under the track so it's out of sight, but this didn't work (note I'm running two parallel fastrack tracks through the bridge). Tried running just a single wire under the track near the middle of the bridge - didn't work. Next tried running the ground wire over top of the bridge (red line) - also didn't work. The one thing that did work was running the ground plane wire over the track, inside the metal bridge (green line).

Since running a wire through the top of the bridge doesn't look that great, I'll likely just use my CW-80 to power the bridge and maybe a few other things on my layout.

Thanks everyone for your help and let me know if any other ideas.

Matt

This message has been edited. Last edited by: mclemens68,

quote:

Originally posted by Will Allen III:
... If you are able to do it, going to a true earth ground outside the house is the optimal and certain solution...

Will, just a follow-up. Given my description above on what I tried in running the ground plane wire under the track, do you think it would improve things if I did go straight to the grounding rod outside?

Referencing the picture of my layout below, I currently have the ground wire coming down a support pole from a cold water pipe just north of the bridge (the red dot near the transformers is the support). It would be a bit of a pain, but I could route the wire across the ceiling out to the grounding rod, which comes in the house near the breaker box which is at the top right of the picture (a bit to the right of the gray circle).

Also, if I try this, what is the optimal place under the track to route the wire(s). Would one wire between the track be sufficient, or should I have a separate ground wire under each track, and is under the center rail the optimal spot?

Thanks,

Matt

As you are learning, the wire antenna works best if you have a physical spacing between the antenna and the metalwork and track. The TMCC signal is strongest in the gap between the antenna and the metal. When you route the wire around the base of the bridge, the antenna is too close to the metalwork to radiate a good field out into the center of the bridge opening.

Placing the wire on the outside of the bridge top generates a good field above the bridge, but the metal top blocks the signal from getting into the center of the bridge.

Tucking the wire into the corners of the metalwork is a common technique we use to shield wires (reduce the chance for radiation) in audio equipment, which is just the opposite of what you want.

Do you have copper plumbing? If so, I would concentrate on your wire placement in the bridge rather than running separate ground rod wires.

Also, you could use a very small magnet wire (22-26 ga) with enamel insulation will work just as well as the insulated (not "shielded") 12 ga wire. One or two wires at the height of the inside top of the arches should work well while being very inconspicuous.

quote:

Originally posted by Dale Manquen:
As you are learning, the wire antenna works best if you have a physical spacing between the antenna and the metalwork and track. The TMCC signal is strongest in the gap between the antenna and the metal. When you route the wire around the base of the bridge, the antenna is too close to the metalwork to radiate a good field out into the center of the bridge opening.

Placing the wire on the outside of the bridge top generates a good field above the bridge, but the metal top blocks the signal from getting into the center of the bridge.

Tucking the wire into the corners of the metalwork is a common technique we use to shield wires (reduce the chance for radiation) in audio equipment, which is just the opposite of what you want.

Do you have copper plumbing? If so, I would concentrate on your wire placement in the bridge rather than running separate ground rod wires.

Also, you could use a very small magnet wire (22-26 ga) with enamel insulation will work just as well as the insulated (not "shielded") 12 ga wire. One or two wires at the height of the inside top of the arches should work well while being very inconspicuous.

Thanks Dale, I do have copper plumbing, so you're right that running a line right out to the grounding rod likely not going to make much difference. I'll play around with the wiring inside the bridge some more. Can you typically find enamel insulated magnet wire at a local hardware or big box store?

--Matt

So even though the other suggestions are all good, I have to ask... What is easier? Running all these extra wires or using an extra power supply. To me this seems like an incredible amount of work for one trouble spot. If the separate supply does the trick, that 2 wires and a transformer. I personally wouldn't over engineer this.

If my issues were more layout wide I would definitely be trying more of the above. But even if you wanted you could use the transformer to supply lights to other objects and things on the layout as well.

Just my opinion.

Over engineering's part of the fun of this hobby .

I see your point Marty and I may end up going this route. Just that if I can figure out how to get working without using the extra transformer I'd prefer to go that route as I already have the ZW, and another transformer will add to what's already a pretty cluttered mess on the floor (need to get going on building an enclosure to get the transformers up off the floor and hide the rats nest).

Matt

The issue is double grounding the bridge with the common side of the lights circuit. If you took a battery and lit the lights the engines would be fine crossing the bridge. This indicates the TMCC signal is fine with the metal bridge. Adding the AC powered lights circuit causes a mis match or ground loop issue that affects the TMCC. You are LUCKY you can just use a small accessory transformer to get out of trouble. Leave the copper pipes alone and keep it simple. A "two second" fix and back to fun operating...

Matt, Radio Shack probably has small spools of magnet wire.

quote:

Originally posted by mclemens68:
Over engineering's part of the fun of this hobby .

I see your point Marty and I may end up going this route. Just that if I can figure out how to get working without using the extra transformer I'd prefer to go that route as I already have the ZW, and another transformer will add to what's already a pretty cluttered mess on the floor (need to get going on building an enclosure to get the transformers up off the floor and hide the rats nest).

Matt

Matt,

I completely agree with what MartyE and Billman730 said. You ARE lucky that a small transformer will remedy this problem in the one weak signal area, and that's definitely what I'd do instead of using ground planes. If you had extensive weak signal areas, then I'd install ground planes, and I'd find the best earth ground I could to do it, but in your case, put in the accessory transformer and be happy.

I also want to acknowledge that Dale is dead on about using small gauge wire and keeping it up and isolated from any metal interference. He is also right to correct my adjective "shielded" when I should have said "insulated" to describe a wire to be used as a ground plane (thanks, Dale).

For what it's worth, on my layout I have a totally separate bank of transformers to light up lights and operate accessories. My track power transformers are dedicated to that single purpose.

Lastly, nice layout drawing in RRTrack!

I have been having the same issue with the Hellgate bridge. TMCC engine stops within the bridge.

This happened under the following conditions

1) Bridge lights not connected up - Loco stops within bridge

2) Bridge lights connected to seperate CW-80 for power - Loco stops within bridge.

3) Bridge lights connected to seperate CW-80 for power. I then connected a wire from one of the bridge handrails and
put the other end on a earthed metal light fitting (pool table light) - Loco operates perfectly.

I use a power supply and inverter setup to get 120V 60Hz power from our 230V 50Hz. This setup is fully earthed or grounded.

I am thinking of earthing the bridge permanently to the earth of a 3 pin plug. I know the earth of the building is spot on as I wired it and it was independently checked and signed off for building regs (our version of code).

Any thoughts on this guys?

Nick

I solved my problem using magnet wire inside the bridge as Dale suggested that then goes to a cold water pipe. Very discreet and you really can't see the wire in the bridge. I'll try to post some pictures in the next couple days.

Matt