TMCC Command Base Ground Pin & Legacy Serial Cable & Wall Wart

Not an issue if you're using the Legacy command base as you aren't using the TMCC track signal output of the TMCC base.  The earth ground is only significant when you're actually using the TMCC 455khz track signal.

John,

Thanks.  That's good news.  So can now use the "good" wall-wart for the Christmas Tree layout, and power the one in the basement with a "generic".  

While we are on it, what is the difference between the TMCC  and Legacy signal output?

-Jim

The actual signal has the same characteristics, 455 khz FSK modulation.  Typically, the Legacy signal is about 50% greater amplitude than the old TMCC base output.

Jim Harrington posted:

John,

Thanks.  That's good news.  So can now use the "good" wall-wart for the Christmas Tree layout, and power the one in the basement with a "generic".  

 

After rummaging through my collection of wall wart transformers, i did not have a suitable generic replacement.  The Lionel one is rated at 12VAC, 100mA.  I ordered up a JAMECO 12VAC 500mA model, as I didn't find one with the correct jack in a lower amperage rating. 

BEFORE pluging it in to the Command Base, I checked it with my meter, and it put out 14.71V  with no load; I added a lightbulb for load and it put out 13.48V.

For a sanity check, I measured the output of the Lionel wall wart, and it put out 13.10V and 11.14V respectively.

Is there a chance that the slightly higher voltage  will damage the Command Base, or does the base have an internal regulator that would dismiss the concern?

Thanks,

Jim

I seriously doubt the slightly higher voltage will have any effect.  There is a rectifier and a regulator when the power come in.

I actually use a generic 9V AC 500mA without any issue.  Here again you must address the grounding issue if you do not tie this to a legacy base.

Thanks.

gunrunnerjohn posted:

I seriously doubt the slightly higher voltage will have any effect.  There is a rectifier and a regulator when the power come in.

Do you know what the internal regulator drops the voltage down to?

DaveGG posted:

I actually use a generic 9V AC 500mA without any issue.  Here again you must address the grounding issue if you do not tie this to a legacy base.

I'm guessing below 9V if this solution works...

Just a wild guess, but I'd say it drops it to 5V.

John,

Thanks.  An endless source of information you are...

-Jim

I have only have had my Cab-1L a month. Tonight it stopped working. With all the amazing information in this site I decided to pry open the transformer.  I can confirm there is nothing amazing going on in there. Anybody should be able to create this until with locally sourced stuff. It’s a step down transformer (10.8vac), a fuse, a jumper wire to the ground pin, and some really poor wiring techniques.

My fuse is blown.  

When the fuse blew in my Legacy command base brick, I replaced it with a PTC.  That protects the unit but doesn't require me to open it again if it ever experiences an overload.

I put the fuse on the outside.

The base blew the fuse, but not knowing, I tried another power supply, blew another fuse. So I had two to fix.

The PTC just fixes is so you never have to worry about the fuse again.

I replaced the fuse and confirmed I had 10v at the connector.  I plugged it into the base and it instantly blew the fuse. The base is not connected to the track.  So there must be a internal short in the base or a faulty part.

John, you mention the PTC but don't explain how to pick the correct one or where to get it.  I suppose in this situation the PTC would make it hard to diagnose the problem.

Well, the fact that it immediately blows the fuse narrows it down considerably!  I'd be looking at the indicated components first.

Here's the complete schematic for the TMCC Command Base if you have to go a bit further.

Lionel TMCC Base Schematic.pdf