Spurious Flipping From TMCC to Conventional

Rick486OGR Forum Member

I’ve been having a problem with one particular engine on my Christmas layout that’s been bugging me. The TMCC operated Lionmaster “Big Boy” has occasional spurts where it goes from TMCC then flipping to conventional control. Of course, when that happens, the loco picks up the full voltage from the track and shoots down the track at full speed. Fortunately by the time it gets to the curve, it reverts back to TMCC and avoids a derailment.

It is an annoying problem and one I mentioned to someone in our local Atlanta train club. This club member, who is our electronic wizard, said that if you have parallel tracks, the TMCC signal can become “out of phase” I believe, causing the train to go into conventional mode. Well, I have 8 TRACKS PARALLEL for about 5 feet in my living room Christmas layout. I obviously can’t change the layout at this point.

So I’m looking at the consist being pulled by the “Big Boy” and notice that there are two all metal cars in the train, a scale coal hopper and a bulk carrier. The rest of the consist is mostly plastic cars. I took the two all-metal cars off the consist and VOILA, the problem went away.

Someone can probably explain why this occurred as I’m not electrically gifted, but I think the all-metal cars somehow amplified the interference caused by the parallel tracks. The problem is only with the ALL-METAL shell “Big Boy” engine, which when added to the metal cars, creates this problem.

Anyway, I thought this was interesting....

12/23/1111:32 AM

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Dale ManquenOGR Forum Member MEMORIALIZED MEMBER

A better explanation of problems with track signals is here.

You can solve the problem by connecting a wire to Pin 5 of the Command Base 9-pin connector and routing the wire between the multiple parallel tracks. One wire in the center might be enough.

12/23/1112:30 PM

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Rick486OGR Forum Member

Pardon me as I'm electrically challenged...but would "pin 5" be the right hand pin on the top row (looking at the plug from the exterior)? And how should it be hooked to the track(s)? To the outside rails of the offending parallel tracks?

Thanks

Rich, The Electrically Challenged

12/26/115:28 PM

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Dale ManquenOGR Forum Member MEMORIALIZED MEMBER

The TMCC and Legacy 9-pin connectors are upside-down with respect to each other, so be careful in identifying pins.
For a TMCC Command Base female 9-pin, Pin 5 is on the top row in the lefthand corner. (My TMCC Base has the pin numbers molded into the connector.)
For a Legacy Command Base, the row with 5 pins is on the bottom row. Pin 5 is in the lower righthand corner.

Wires to Pin 5 are placed between the tracks as antennas, but they MUST NOT connect to the track!! They just dead end there. If you test with an ohmmeter, there should be no continuity (an open circuit with infinite ohms) between Pin 5 and the outer rails.

12/26/115:45 PM

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Rick486OGR Forum Member

Yes, thanks, I've looked at the Command Control 9 pin plug and I see the numbering on the pins. I'll try your suggestion.

12/29/1110:11 AM

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Rick486OGR Forum Member

As Dale suggested above, I did try running wires hooked to the #5 terminal of the CC plug, first on one side then both sides of the offending parallel track, however the problem continued.

Obviously, it has to do with the "weaker" antenna (handrails) on the metal shell loco, I think--easy now, remember I'm "electronically challenged". Sometime in the future I may open the shell and examine how the antenna is hooked up and possibly add some additional "steam pipes" (black wire antenna)to the exterior boiler and see if that helps.

Otherwise, I'm stumped on this

1/22/123:08 PM

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gunrunnerjohnOGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER

I'd check the antenna connections, maybe one or both are disconnected...

1/22/124:17 PM

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Dale ManquenOGR Forum Member MEMORIALIZED MEMBER

Rick, now that we have a photo of your layout available, could we go back to your attempt to add a ground-signal wire? Where did you place the wire, and where was it connected?

2/1/127:07 PM

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Rick486OGR Forum Member

Thanks Dale for your continued help to solve this problem. If you look at the layout in the photo, I ran the "pin #5" wire from the beginning of the straightaway, just behind the car on the track behind the "B" arrow and continued up the "B" straightaway to just before the bridge in the foreground.

I initially tried just one side (closest to the fireplace), taping the 30 ga wire to the FastTrack roadbed on the up or visible side. No improvement in the jumping to conventional along straightaway "B". I then continued the wire under the track at the bridge and ran down the other side of "B" track, i.e., both sides of the track had a wire connected to #5 pin of the Cab Controller. No improvement.

Someone in my train club suggested I connect this supplimental antenna wire to the ground of the wall socket. Again, no improvement. There is some improvement when I clean the track and the wheels of the UP Big Boy, but it still jerks full speed somewhat.

I put the offending locomotive on Loop "A" and it jumped to conventional on that straightaway in front of the fireplace, similar to when it was on Loop "B". Oddly, of my 6 TMCC engines running on this layout, including a Digital Dynamics TMCC rigged 027 Polar Express (in which all the electronics and antenna were in the PLASTIC tender), the Big Boy is the only one with this problem. One of the non-offending engines which doesn't jump to conventional is a METAL SHELL scale Lionel GG-!, so the metal shell is not necessarily the problem causing agent.

Thanks again for any insight....my next step will be to buy some TV rabbit ears from Radio Shack and bolt it to the cab of the loco.

Rich

2/1/129:28 PM

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Rick486OGR Forum Member

Solved problem by sending back to Lionel repair (Ohio). They replaced the electronics and fixed a broken handrail stanchion. Now runs flawlessly. Here's the layout that was causing the problems in the early construction stage: