Lionel Mountain Smoke Unit Fixed; Now We're Cookin'!

Is 16 ohms ok to use with tmcc electronics. May try one in my unit. Great smoker!

That looks great Rod!  I'm glad you got it working well.

When I received the locomotive last year, the smoke unit was dead. I purchased a new one from a Lionel tech who said it was 'modified' to smoke better. It would smoke well but only when I ran it at 19v-20v and hit the boost from time to time as shown here. Looking at the 27ohm resister you removed I can see what my boosting did!

At the normal 18v it would barely smoke at all...

You're probably pushing the triac pretty hard.  If you have room, I'd probably consider rigging a small heatsink on the triac to help it dissipate the heat.  Pretty much any shape will do, just some mass to help with the heat buildup.

Also forgot to ask. Can the 18 ohm resistors be used in puffer type units? Or Would the heat from the resistor melt the insulation that goes through the pot metal of the cap. And as their is not constant air flow as with a fan driven unit.could the wicking char faster?

Can anyone point out the physical location of the smoke unit triac on the R2LC board??

I assume it's perhaps a TO-220 package or something similar?

I also found out something quite interesting.

Most MTH engines ramp up the current draw by .7 to .9 amps or so wheen the smoke unit is switched on.

Surprisingly there is no difference in the current draw when the Mountain's smoke unit is switched on or off. Can't quite figure that one out yet.

 

Rod

I may have an answer for you very soon.

My next project is a K-Line Berkshire which has a lethargic plunger puffer style smoke unit. We will see what an MTH heater will do for it.

 

Rod

Sam;

I am pleased with the results because now it smokes quite well at normal track voltage of 18 VAC or so. Plus no boost is needed at all.

That original resistor actually does not look bad at all as far as charring. I have seen much worse. None of the original batting was fused to it at all. It just does not get hot enough to make decent smoke.

I removed all the wadded batting and just used a rope of tiki torch wick material per the pictures.

Rod

Rod,

I bend the wire resistor a little towards the fluid input hole so fluid drops down onto the resistor there. Regardless, your engine smokes real well there. The 27ohm one that Lionel used then did not get hot enough and that was the reason why folks had to turn up the track voltage to 20 volts just to get smoke emitting from their engines.

OK my mistake. I was misreading my ZW ammeter.

The power draw increases by about .6 to .7 amps when the smoke unit is switched on. That is pretty close to what an MTH draws and to my thinking is right in line.

So I don't think that the triac or anything else is being overloaded by the new smoke resistor.

 

Rod

Lionel service tech said he replaces all units he repairs with 27ohm resistors. I tryed two tied together in a Lionel puffer type.I got great smoke output but ask tech and he said I could damage somthing so that's when he told me he uses the 27 ohm ones in all his repares.I also found out from authorized repair tech and owner of electric train outlet. Bob is his name that Lionel uses the ceramic coated ones in most starter set locos because they don't burn out as bad as wire wraped ones. He said these engines are targeted mostly to newbies and because most of the time they don't keep proper amount of fluid in them and will run them dry.the ceramic ones hold up better. although they don't produce as much smoke they feel the trade off is better than having an angry customer who has to send it back in for repair. Also if while mike regan when still at TAS developed their smoke unit which is supposed to not burn out when low on fluid.I think they were called supersmoke. I saw one of these in action.I think in a video somewhere and it smoked great! Why is Lionel not using these units in their products?

 Those Ceramic Smoke elements are junk. I have replaced them with the Wire wound ones with good results. I use these when converting Pill type elements to liquid also. 

Instead they send them back in droves saying the smoke unit doesn't work anyway.  You then have to hand it back saying it is just a poor smoker.  I think it is rubish.  The on off switch protects the smoke unit, put it on every engine even the starters.  As Forest says the wire wound are much better.  Heck, install the older unit from the PW era, they seem to smoke even 60 years later and they work with liquid.   G

The Triac is Q1 on the circuit board.  If you can read the ID number off it, you can do a data sheet search to determine the rating.

 

At the voltage used on the smoke unit I think you will be ok.  If it goes, you can replace it with a one with a higher current rating.  Not sure you can get a heat sink on that package style.

 

A TRIAC is a device that can act as an on off switch for AC current flow.  Power comes in on one lead and goes out to the device (smoke element) via a second lead.  But the device is off.  The third lead is the trigger for turning the triac on.  A small current flow into this lead from the (R2LC) turns the device on and large current flows uninterrupted from the power source (track) to the device (smoke unit)

 

Unlike DC transistors where current can only flow one direction, triacs can handle alternating current from our AC track voltage.

 

I have put 16 ohm heater elements in sleuth units, but I use a sleave around it. (This is how most sleuth styles operate).  Since the starter engines can run pretty fast down at 10 volts your only pulling .625 Amps (10/16).  6.25Watts.  The bulbs in a night light are 4 watts.   G

 

 

  

The Lionel 27 ohm wirewound resistors work very well. I have swapped out a lot of the ceramic ones with them and have gotten great results! Here is a video of my Polar Express Berkshire with whistle steam with one installed 

I havealso found that pink insulation works very well as batting as long as you install it properly and soak it well with fluid. In the video I am using Jts mega steam smoke fluid.

On newer boards, the 2N6071A is used, however for older boards they used the T2322B.  For any replacement, the preferred choice is the 2N6071A, it has a higher maximum current specification.  You can get the datasheet from Digikey.

 

Heatsinking is still a really good idea for a higher current smoke resistor.  Note that you are also putting more current than they probably designed it for through the PCB and motherboard, don't know what effect that might have.  I have had shorted smoke unit wiring take out a trace on the motherboard and not the triac, so that's a consideration.

Thanks to everyone! Now I am understanding this triac part and how it works with the smoke unit. One question. What would one use as a heat sink? And what is the bolt and nut size? And if I am reading you correctly John. You attach the heat sink directly through the hole on the triac itself. On the side with heat sink of course right?

The heatsink can be pretty much any metal mass, obviously the ideal is something that will have surface area to conduct the heat away from the triac.  I don't think many conventional heatsinks will work here, since the positioning of the traic on the board wasn't done to allow them to fit.

 

You just bolt it contacting the metal side of the triac.  I'd probably use a small chunk of aluminum around the corner.

 

IMPORTANT SAFETY TIP:  You must insulate the heatsink from the device with a thermally conductive spacer as the metal side is conncted to pin 2 of the triac!

Rod, FWIW the 2N6071A is rated for 4 amps. Worse case with 22 volts and 16 ohms you would be drawing ~1.4 amps through the triac assuming its not driving the fan as well. A heat sink wouldn't hurt though. BTW don't use those 16 ohm resitors in a plastic car like a smoking caboose unless you are trying to model a wrecked one.

 

Pete

Note that it's rated at 4 amps properly heatsinked!  It's not rated at anything close with no heatsink.

Rod, If the smoke resistor is connected directly to the Triac the voltage to the resistor will essential be track voltage minus a few volts drop of the triac. That would account for the lower current draw.

 

BTW assuming the resistors are wound with nichrome wire, the value will not change very much with temperature. nichrome has a very low temperature coefficient which is one reason why its used.

 

Pete

The triac is NOT protected against excessive current or heat, it's a simple device.  The Thermal Resistance, Junction-to-Ambient is 75 °C/W.  I believe that would say if the package is dissipating one watt, the junction temperature would rise 75°C assuming no heatsink.  With an ambient of around 30 inside the shell at the board, you're almost at the maximum junction operating temperature.  I suspect with no heatsink and a 16 ohm resistor, you're running very close to the maximums.

 

Again, I recommend a heatsink.

 

We're also talking about the 4A device, the older R2LC boards have a 2.5A device.

John;

I have studied the data sheet and I see that the triac is not overload protected, as you indicated.

From what I can see from the power dissipation curves for RMS current, the worst cas dissipation at .7 amps load is about .7 watts. Using the 75C/W junction to ambient value, this should produce a junction temp of about 50+30=80C; well within the 110C limit.

I figure the triac is likely good for any load up to about 1 amp with no sink; but I agree a sink would be wise regardless.

Next time I have it apart I will look at attaching a small sink. I may be able to cut down a TO-220 sink and shoehorn it in.

Thanks to all for the comments and suggestions.

 

Rod

Remember when you go into boost you get additional current through the resistor.  Granted, you don't do that often, but it's a consideration.  That little triac's heat dissipation isn't all that good, and it's also packed in with the rest of the components.  In any case, you're running somewhere close to the edge.

The Triac on the R2LC was pretty tight as I remember, not sure if a heat sink will fit.

 

How many folks have a smoke triac burn out other than a direct short?  G

Can't really say, I've seen threads on triacs being out with no stated shorts, but it's hard to say what actually happened.

 

Depending on what's beside it, you could have a heatsink alongside the board, the metallic side of the triac is at the edge of the board.

Here is a pic of the smoke triac on the R2LC.

 

 

 

It is along the side of the board, and the metal part faces outward. So it should be easy enough to cut an aluminum tab say 1/2" wide x 1" long with a hole in one end. It should clear any boiler obstructions without issue.

 

I ran another test of current load with boost and without.

Guess what: there is no difference! .7 amps with boost and the same without.

So can any trained Lionel techs tell us what exactly the boost does to produce more smoke, since the triac is simply an AC on/off switch?

It can't be increasing the voltage to the smoke unit, as this would increase the current as well, and it is supposedly running at full track voltage already.

 

Rod

Rod, the smoke unit heater receives half voltage from the triac in normal operation. When the BOOST button is pressed, it allows full track voltage to the heater, that is why it is easy to burn the heater out if you hold it for more than a few seconds.

So can any trained Lionel techs tell us what exactly the boost does to produce more smoke, since the triac is simply an AC on/off switch?

It can't be increasing the voltage to the smoke unit, as this would increase the current as well, and it is supposedly running at full track voltage already.

 

I'm not a factory trained tech, I just play with trains. I always understood the boost to be an increase in voltage. I found this on the internet to back it up so it must be true.

 

Steve

OK it all makes sense now.

Thanks to all who posted answers and suggestions.

 

The best,

Rod

Now, that was FUNNY!

Rod,  I do think this is getting over engineered.  I believe the values you are seeing are correct and well under the rating of the TRIAC.  Placing a small heat sink with no air flow, and not mounted to a larger heat sink won't do much.  It will just take slightly longer for the TRIAC to reach equillibrium.

 

Most items that are getting heat sinks carry much higher current and are mounted to the chassis a much larger heat sink.  Full Bridge Rectifiers, motor driver TRIACs, etc...

 

You run more risk damaging the $45 R2LC, then saving the $1 triac, but like Tool Time "More Power"....  Just an opinion here.  G

Rod,  The smaller TRIACs are the MAC97 which are 1amp.  Good for the lights and couplers.

 

For the Turbine fan experts out there, it looks to me like the impeller blades are curved the wrong direction for the orientation of the vent to the smoke chamber.  I would think the blades should be reversed with a Clockwise rotation?  G

I was told the blades are curved to reduce noise and it really didn't matter which way the curve is, it still produces the same amount of air flow.

Since there is obviously no way to change the shape of the blades, I'd suggest the fan is in there correctly.

 

And you talk of over-engineering?

Chuck,  Thanks, maybe they are correct and the design creates the low pressure area to draw in the air in.  I just don't remember the theory from my College days.

 

John, I was just questioning if there was an error when manufactured.  Weren't there some fans wired to run backwards at the factory?  Lionel units aren't known to be good smokers and with all the mods required, it is not so far fetched that an item is built incorrectly.  Maybe it just needs a heat sink on it:-)  G

 

Well, it could be wired backwards, that's certainly true.  OTOH, you were commenting on the shape of the blades, something that probably wouldn't be affected by wiring.

 

John Your a tough cookie.  My point being that manufacturers make errors, therefore blade orientation could be an error, I realize wiring doesn't effect the blade design.

 

I think Chuck nailed it.  I did some research.

 

collection impellers use impeller blades which are straight, angled, and curved. Straight blades make lots of noise but work well. Blades angled away from the direction of spin known as backward inclined or BI blades reduce noise but also reduce airflow efficiency. Backward curved or BC blades have the curve part lead and the blade tips trail. This also reduces noise without so much loss in efficiency. You can run a curved blade backward and it generally will move more air and generate more pressure, but at a big cost in noise and increased horsepower draw.

 

So to limit noise and motor current draw, the blade is a BC blade, but does reduce the air volume output slightly.

It was just such a tempting target.   I'm guessing the airflow would really suck if they wired the motors backwards. but I'll bet it probably would send some air out.

BC or BI blades, or whatever they are, the Mountain smoke unit moves some air now, and makes lots of smoke. (So far the triac is still happy.)

 

The next problem I have encountered is that the stack inner hole diameter is too tiny at  only 5/32" diameter, which produces a wimpy thin smoke plume that shoots straight up about a foot or more above the engine. Not too realistic.

So I drilled it out to 7/32" diameter. That's nearly a 100% increase in flow area.

Now the plume flows much thicker and exits with more turbulence. It doesn't shoot straight up high above the engine. It looks loads more realistic to my eye.

 

Next on the agenda is figuring how to make it chuff instead of just a steady flow.

One idea I have is to replace the SPDT cherry switch (that sequences the chuff sounds) with a DPDT cherry switch, and using the second set of contacts to interrupt the power to the fan motor. Then I figure I will add a small resistor across the switch leads so that the fan will turn at a slower speed when the switch is open. I expect that there will be some experimentation with the resistor values.

 

The poor hapless Mountain has become a test bed for all manner of mad experimentation! Ya gotta love trains. There is always something that can be improved.

 

Rod