TMCC & Smoke

A triac on the R2LC board?

Not sure what a triac is.

Its an solid state AC switch. Here’s a diagram...

https://www.google.com/search?...mgrc=52KHRVJaSFN7LM:

Oh I see now!  This plugs into the mother board correct?  Come to think of it, the backup light on the tender is flickering irratically while the locomotive is in forward motion.  This board controls that feature as well correct?  Where can I purchase one of these?

Lionel parts...half price sale if you wait until Nov 3rd

Someone said that back up light flickering is a chronic issue for that vintage. A new same board may not fix that.

There’s an R4LC- 08 that I think can be subbed for the R2LC...I wonder if that would be a better choice. Maybe someone with the experience will chime in here.

Actually that flickering is not a big deal for me, I just want it to smoke.  I just found a brand new board on eBay for $40.  I think I’ll go ahead and order that.  I thank you for sharing your knowledge with this newby.  

You can buy R4LC boards with 08 code from Electric Railroad.

Thanks Roy

RoyBoy posted:

You can buy R4LC boards with 08 code from Electric Railroad.

Or wait a week and buy them at 1/2 price from Lionel during the annual half price parts sale.

$40 now, $20 in a week.

Thanks guys

I replaced the R2LC board today followed by doing all the required resets per the instructions and still no voltage and no smoke at the smoke unit in neither command nor conventional modes.  Could it be the DCDR board instead?  

The DCDR has nothing to do with the smoke, and even pulling it out of the locomotive would not affect smoke production.  If you still don't have voltage at the smoke unit, trace the wiring, top suspect is the smoke switch.

The other possibility is a short in the smoke wiring to frame ground, that would take out the new smoke triac on the spot.

I traced the hot side of the smoke unit all the way back to the motherboard and still no current.  Switch continuity is good.  Smoke unit itself has been tested as well and no short to ground could be detected.  

John,  are these triac’s prone to failure even if there is no short?  

They're not prone to failure unless subjected to over current.  Did you test the path all the way from the smoke unit to the R2LC socket pins 5 & 6?  Are you sure you're programming the R2LC with the correct code?  That one should be AUX1-4 for a steamer with smoke.

I did all of that but I went back last night and rechecked the smoke unit itself and did find a short to ground.  That being said, I guess that new board got fried as well.  

That triac is easy to replace. The little ones are somewhat harder...lights and stuff 

Chuck, do you know the part number and where can I order it?

I buy them at Digikey, all the little ones are the MAC97A6 (or MAC 97A8), the smoke triac is the 2N6075BG.

2N6075BG at Digikey, 69 cents each.

Thank you John!  I just ordered a few and will install it when they come in.  I’ll go ahead and install a new smoke unit as well just to be on the safe side.  BTW,  what should the normal voltage level be at the smoke unit when it’s working?  I don’t have and schematics to look at.

In command operation, the voltage out of the smoke unit is half-wave track power.  For conventional operation, it's full-wave track power.  Also, with no load, you'll frequently get no voltage out, the triac needs a load to trigger.

Got it!  Thank you very much John.

Ditto 🤓