Question on Electrocouplers in Legacy

Have you tried disconnecting the coupler electrically?  You would then be able to determine for sure if mechanical or electrical.

If an older R4LC based Legacy, the Triac drive is from the 3rd rail to the coupler, and the coupler returns to track common.  If a newer RCMC Legacy then the couplers are fired on DC from a MOSFET.

SantaFeFan posted:

If an older R4LC based Legacy, the Triac drive is from the 3rd rail to the coupler, and the coupler returns to track common.  If a newer RCMC Legacy then the couplers are fired on DC from a MOSFET.

Very good.

I will research my exact model a little more. It almost seems like there is occasionally a coil to mechanism short, and the metal coupler and truck of the following car complete a circuit to ground and cause it to open, but that may not be electrically possible. Sure is weird, with a metal coupler/truck following it opens every second lap or so around the layout, with a plastic coupler/truck it never opens.

I may just chalk it up to "The Perversity of the Inanimate." 

Thanks again for all your help!

My RX for these is to unplug it and see if it still opens.  That narrows it down between mechanical and electronic.  If it's electrical, try a 1uf 50V capacitor across the coupler.  The easiest place to add it is usually under the motherboard connector for the plug. 

Note that this is ONLY for the older ones fired by the triac, don't put a cap across the RCMC DC powered couplers.

I have one of the new UP auxiliary tenders and one of the couplers opens I think when turning on track power. I haven't analyzed the circuit. Anyone else have this tender coupler issue?

gunrunnerjohn posted:

My RX for these is to unplug it and see if it still opens.  That narrows it down between mechanical and electronic.  If it's electrical, try a 1uf 50V capacitor across the coupler.  The easiest place to add it is usually under the motherboard connector for the plug. 

Note that this is ONLY for the older ones fired by the triac, don't put a cap across the RCMC DC powered couplers.

Your comment is interesting, I figured I would get a bunch of responses stating that it had to be mechanical. Looks like you have had similar issues in the past.

I hate pulling that engine apart, the way the cab lights are installed they interfere with the side of the body during installation, so you need to loosen the cab light supports just enough so the lamps can deflect to clear the body. Even so, half the time the bulbs get pulled off the supports and need to be re-glued. Not to mention the "gasket" between the smoke funnel and the body. I have been using foam tape as an experiment, we'll see how that holds up.

Do you have a theory on why your capacitor idea works? Not doubting it, just curious.

P.S.

My loco has the R4LC.

gunrunnerjohn posted:

If it's electrical, try a 1uf 50V capacitor across the coupler.  The easiest place to add it is usually under the motherboard connector for the plug. 

Note that this is ONLY for the older ones fired by the triac, don't put a cap across the RCMC DC powered couplers.

It was my impression that Legacy engines had these from the beginning.  Is that not correct John?  Also BTW will Hennings have Super Chuffer and Programmable chuff Gens at York?

PLCProf posted:

Do you have a theory on why your capacitor idea works? Not doubting it, just curious.

P.S.

My loco has the R4LC.

In the absence of evidence to the contrary, I'm assuming it's electrical noise that's affecting the triac triggering.  The suggestion of the cap was advanced by Lionel years ago, and since it works, I just use it.

Marty, the R4LC uses the AC triac the same as the TMCC locomotives, it's only the later RCMC that uses DC to fire the couplers.  I have cured my older Legacy GP-7 with a capacitor, so if a cap was already there, it's not working.

We will indeed have the Super-Chuffer, the Chuff-Generator, as well as the passenger car lighting kits and regulators at York.

If it is electrical interference, stray electricity will be stored in the capacitor instead of hitting the coupler.