The TMCC and Legacy Flickering Headlamp Mystery

Well, the tender IR connection has nothing to do with this issue, I can tell you that.  The tender connection is a one-way optical connection, it is transmitted from the locomotive to the tender.  The locomotive doesn't even know the tender is there.

How about the actual product numbers of the problem steamers?  I can't imagine this has anything to do with the fact that these have the optical link to the tender.

John, thanks. I'll check the product numbers. I seem to recall I did get a TMCC steam engine with an tether connection on eBay that I returned and also saw the flickering headlamp. It's weird. I did see a thread long ago where there was something like that and it had to do with poor ground in a power strip that the Cab 2 was plugged in to.

The flickering lights are a sign that the TMCC signal is weak as a rule.  This has nothing to do with the tender, it's strictly a locomotive thing.

As a test you can try the following. Hopefully you have an extension cord that has three prong plug/slot receptacle - this extension cord will have hot, neutral, and earth ground in it. Turn all power off. Unplug the AC to the TMCC base and plug base into extension cord, then plug other end of extension cord into the AC outlet the TMCC base had been plugged into. Run the extension cord along the outside of your track where ever you can, power up, and see if your engines run okay on the track in the area where the extension cord is run.

Earth ground is part of the antenna system that makes TMCC transmission possible.

I will repeat the basics which you may have already done, but here goes.   Much of this has been compiled from the collective wisdom of the OGR forum.

1. TMCC signal problems
As others have stated, you probably have a weak TMCC signal combined with less efficient antennas in the 2 steam engines.  Make sure that your base power supply is plugged into a 3 prong outlet directly or through a 3 wire extension cord (not a power strip).  You may even want to test the outlet ground with an outlet tester.  

The extension cord test outlined by MED is helpful.  If it fails to fix the problem, at your workbench, test your locomotives on a section of track connected to your base.  This will confirm that the signal from your base is good, but now you are back to troubleshooting the layout. If by chance the 2 steam locomotives fail here as well, you may have antenna problems on both locos and less likely a faulty base.  You may need to confirm this by testing the locomotives on another layout.

If the extension cord fixes the problem, here are permanent solutions:  

If poor signal only occurs in certain areas of the layout, lay a wire near the track in the affected area connected to earth ground. The preferred earth ground source is Pin #5 on the DB9 connector on the TMCC or legacy base or the outside barrel of the command base power brick.

Alternatively buy a 3-prong electrical plug and attach the wire to the ground plug (DO NOT DO this option if you are not 100% sure which plug is the ground plug. I don’t want to be responsible for your electrocution.) The wire should not be run in a bundle with any wires feeding power to the track, nor should it be run closely parallel to the track.
The wire should be at track level or above (preferably above) and minimum 2-4 inches away from the track. Telephone or Telegraph pole wires are a good way to accomplish this if a track level wire does not work.  

If you determine that the locomotives are the problem, here are some troubleshooting steps

2. Locomotive Signal Problems
a. Antenna problems. In a diesel locomotive, remove the shell and trace the antenna wire.  It will either be connected to a handrail or may be taped or glued to the inside of the shell. Check continuity from the handrail to the chassis. It should not be shorted to the chassis. If you don’t find it disconnected or shorted, try connecting a short wire in place of the antenna lead and run the locomotive without the shell. If that fixes the problem, you have a broken or shorted antenna.
In a steam locomotive, the antenna lead can be in the engine or the tender. In the tender, it is either buried under the coal load or connected to the metal shell of the tender (which is insulated from the frame). In the engine, one of the handrails is used as the antenna (insulated from the shell). As with the diesel loco, make sure there is no continuity from the antenna to the frame. A common problem is the brass tender shell shorting out to the frame. Often, the only insulation is electrical tape. To verify an antenna problem, try connecting a short wire in place of the antenna lead and run the locomotive without the engine or tender shell (wherever the antenna is located. Antennas function better if separated from a grounded chassis or shell. Even a ¼” separation can help. Use as long a wire as is practical.

b. Failed board connections
Check if board is seated properly and retest. Then pull out the board, check for broken pins and connectors on the motherboard and the TMCC receiver. Note: Whenever removing/replacing boards, be sure to line up the 24 pin connectors properly. They can easily get offset by 1 pin, which will burn out components when you power up.

c. Failed Radio board
If the above procedures fail, then the likely problem is a failed (or failing) R2LC or R4LC radio board. Replace with a known good radio board.

Bob

Thanks Bob and MED. And ouch, that's my bruised ego. I now remember when I was adding the Cab 1L that I needed good ground. I checked the primary power outlet in the train room and the ground was shaky. So I crawled under the house, ran a heavy gage copper wire to a ground spike and got good ground on the outlet. Then, , I plugged a power strip into the outlet, connected another power strip to that power strip and then ANOTHER power strip and plugged the Cab 1L into that. Yikes. I did plug the Cab 1L straight into the wall outlet this am and still no headlamp but at least I'm headed in the right direction. Next, I'll follow Bob's advice and connect the Cab 1L directly to my test track and see what I get.

You have to be careful adding a ground.  There should only be one earth ground and that's at your main panel.  Code these days requires 2 ground rods a minimum of 5 feet apart at the panel.  If you add another seperate earth ground you can create ground loops and possibly affect the function of gfis since the leakage current could have a path other than to the main panel ground.  Perhaps running a new power feed for the layout directly from the panel would be the best solution to a shaky ground at your layout outlet.  And subpanels should all connect to the main panel earth ground.