R4LC function.

The "smoke" output for the Legacy R4LC took on a new function.  I believe it's used for cab lights, at least in some models.  The AC Regulator supplies power to the smoke unit, but many Legacy models also have a separate smoke fan control that would control the smoke fan.

The Legacy R4LC performs just like the TMCC R2LC. It will still drive the smoke resistor directly. If you use an older non Legacy smoke unit that has a 5v regulator for the fan motor then the fan will come on for as long as the resistor is powered. It won't puff in synchrony with the chuff though. You need a separate chuff switch for that but that only goes to the motor. In an early Legacy engine that uses a R4LC the AC regulator is used to control resistor power for speed and load based on the serial data fed to it.

Pete

Not really true Pete, you don't have control of the smoke with the smoke keys on the remote if you try to control it from the remote.  The smoke triac with modular Legacy is not used for smoke.

All the modular Legacy models used the smoke regulator, hence the smoke triac on the R4LC was repurposed for other uses.

John, it is true. That is what I an using in my Legacy CV with a TMCC Niagara smoke unit. Works with Aux1 8/9 just like a TMCC engine. This a true R4LC from Lionel not the dumbed down ERR version.

Legacy engines use the AC regulator but it doesn't alter the ability of the R4LC to respond to signals and drive smoke units.

Pete

I'll modify my statement slightly, but stand by most of it.  The R4LC-S01 appears to indeed respond to the conventional smoke controls.  However, R4LC-S02 through R4LC-S05 ignore the smoke control.  I just personally tested all of them on my test rig.  Most of the Legacy stuff I see has the R4LC-S03.  I don't believe there ever was an R4LC-S04, at least I've never seen one.  I tested the S01, S02, S03, and S05 versions.  Only the S01 responds to the smoke controls.

That implies the triac can not be addressed in any way, not even to turn on a cab light. Pretty sure no R4LC engine had rule 17 lighting so the processor wasn't turning it on.

Pete

I don't know what it implies Pete, I tested them in both TMCC and Legacy mode, and nothing I do to the remote changes the state of the smoke output on anything but the S01 version of the R4LC.  I don't know what, if anything, they use the smoke output for in those later locomotives.

I happen to have a wiring diagram for the early Legacy GP7, and I also happen to own one, the 6-28587 PRR GP7 #8510.  It features automatic cab light control.  I look at the diagram, and there is nothing coming into the motherboard that could offer this control, so it has to be on the motherboard somewhere.  The motherboard is a dumb motherboard with no logic.  The only thing on the motherboard that would control that cab light in my mind is the R4LC, the RS 5.5 or generic power supply isn't likely to be doing it.  Not sure why it doesn't toggle that output in my test set, this engine uses the R4LC-S03.

You may have answered the question if the cab light toggles. I will have to check my R4LC to see what version it is. I know mine will turn the smoke on and off. I had to turn it off on my CV at a show as I was choking everyone out.

Pete

I know the cab light in the GP7 is connected to something as it automatically goes off when you start moving.  Interesting enough, I can't find any key that will allow me to turn off the cab light in my GP7.  But that still doesn't answer the question as to why I can't affect the smoke output on my test set.

Still some little mysteries to sort out for these boards.

If you have other than the S01 version and it responds to the smoke controls, I'll be really confused!