Turning off my GP-30

 It sounds like your loco may be dropping into conventional for a split second.

Try powering up the Legacy base first. Then the layout. It  can take a second or two for the legacy signal to get to the track.

RickO,

Thanks very much. What you suggested worked. Seems like your analysis was right on. I am thinking that must be something of a defect in the engine if it doesn't happen with any other locos.

That scenario may happen if it was the last engine you ran. I have a GP9 and SW1 sitting on tracks and thee SW, which gets run quite frequently will start soon as the track is powered before the Legacy Cab-2 kicks on

Fairly common issue, and several people have cured it by adding a delay to the layout power to allow the Legacy command base come up first.

Thanks for your reply. Unfortunately I don't know how to do that. It was also suggested to me that I turn the Legacy base before turning on the power to the track and that seems to have worked but it surprises me that Lionel doesn't have a fix for this rather than a work-around. 

Thanks also to Dave for your reply. I tried having the GP-30 not being the last loco used but that didn't work. 

The "fix" is turning on the Legacy system, not actually a huge problem, right?

I did something along this line for a bench power supply.  The supply was prone to having voltage overshoot upon power-up, so I delayed the power to the outputs for a couple of seconds to insure that the power was stable before it was connected to the output posts.

Interlock Relay Project for Common 30V 5/10 Amp Bench Power Supply

The two modules used here, the 110VAC -> 12VDC power module and the 10A time delay module  would be put in a metal enclosure with your layout power plug going in and the layout transformers on the output.  Total cost of the two modules was only a few bucks.

Saying that Lionel needs to come up with a "fix" implies that there is something wrong with the Legacy system when, in fact, there is not.

Legacy was designed so that both command control operators and conventional train operators could both operate highly detailed, scale locomotives and that conventional train operators could enjoy running those locomotives w/o having to purchase an entire new operational system. 

In order to satisfy both kinds of operators (it's important to Lionel to make their products backwards compatible as much as possible), Lionel came up with a system whereby when first turned on, the Legacy system sends out a "watchdog" signal. If a Legacy engine "sees" that signal, it knows to start up in command control mode. However, if the Legacy engine does not see that signal and the power is turned on before any "watchdog" signal is received by the engine or if  no signal is sent at all, the Legacy engine knows to start up in conventional mode. 

There's nothing inherently wrong with that system because it's designed to let both command control and conventional train operators to buy and operate Legacy engines.

If you put your Legacy base on a separate power source, like a different outlet or power strip and turn that on first before you power up the layout, that should do it. On my system, I have the Legacy base plugged into a separate strip and leave it on 24/7 to charge the batteries and add the engine I'm going to run to the remote before turning on the transformer. Not much of a "workaround".

Richie,

Thanks very much for your detailed explanation. I learned a lot and now have an understanding of how it works. One thing I am still curious about. I have six or seven Legacy locomotives and the only one that reacts this way is the GP-30. 

Thank you GunrunnerJohn,  your explanation was very helpful and makes me understand I have a lot more to learn.

@Lionelhampton posted:

One thing I am still curious about. I have six or seven Legacy locomotives and the only one that reacts this way is the GP-30. 

Not uncommon, most people that have this only experience it with a few engines, not all of them.  Hard to say what the variables are.

Thanks again.

@Richie C. posted:

"Saying that Lionel needs to come up with a "fix" implies that there is something wrong with the Legacy system when, in fact, there is not."

"In order to satisfy both kinds of operators (it's important to Lionel to make their products backwards compatible as much as possible), Lionel came up with a system whereby when first turned on, the Legacy system sends out a "watchdog" signal. If a Legacy engine "sees" that signal, it knows to start up in command control mode. However, if the Legacy engine does not see that signal and the power is turned on before any "watchdog" signal is received by the engine or if  no signal is sent at all, the Legacy engine knows to start up in conventional mode."

I was unaware Lionel has a "Watchdog" signal, thought that was only MTH, and that Lionel just needed the base powered up prior to track power.

TMCC/Legacy doesn't have a watchdog per se, it's just that the 455khz TMCC track carrier signal comes on.  If the carrier is present, it alerts the engine that is powering on that there is a TMCC command system in operation.  It's a continuous carrier from power-on to power-off of the command base.  The DCS watchdog is only emitted as specific times, specifically when the TIU channel is first powered up. 

The issue being discussed here is the TMCC/Legacy electronics may miss the TMCC carrier if you switch the base and track on at the same time.  Reason being that it takes the command base a small amount of time before the 455khz carrier is being generated, and the engine may have given up and dropped into conventional mode.