Recommended Improved Convention PE smoke resistor

I'd be interested in this info, too.

I ran our Polar Express set for the first time this Christmas.  I added smoke fluid and turned on the smoke unit.  It hardly smoked at all.  I tried some more smoke fluid and same result.

The next day I saw that the fluid had come right through the engine.  It was on the track (fortunately Fastrack so it didn't get down to the rug) and the loco.  I took off the shell and discovered that there was no wadding in the smoke unit!

The next time I went to run it, I got a short circuit.  I verified that a cat hadn't derailed anything.  Then I realized that I had forgotten the smoke unit was still turned on.  I turned off the smoke unit, and it ran fine.  So, I must have burned out the smoke unit.

I'm not sure what part(s) I need to make repairs.

Paul,  what is the item number of your engine, so I can see what OHM resistor your engine came with. Then we can decide what lower value resistor we can use.

VinceL, when you took off the shell, did you open the smoke unit or move the resistor

around at all. If you did,the positive side of the resistor must have hit the side of the smoke unit and shorted out. You most likely just need a new resistor. I would need the item number to look this up

Alex

Alex, my polar express is the older one with the smaller motor from 2004 / 2005 time-frame (pre CW80 G Revision which was in 2006).  I'm not sure where the box is, but I remember that much, and I was able to upgrade it to ElectricRR mini-commander because there was still room in the boiler unlike the larger motor version.

If that's enough to go on, that will save me the trouble to digging around my storage closet for the box, but I should be able to produce that with some digging.  The loco has never been put back since purchased.

Its probably a 30 ohm resistor.

Bill

Thanks Bill,

I can't find anything on it, so if it's a 30 ohm he can go down to a 24 or 22 ohm

without making things get to hot.

Alex

I took a different approach after speaking with gunrunnerjohn. You'll find the engine will run at ~5v at a reasonable speed with little smoke. At 7v the train is going very fast, but produces a lot of smoke.

The solution: Leave the puffer unit alone and place 2 diodes in the power feeds before the motor. This requires increased voltage to attain the same speed, but puts the 7v or more to the puffer unit as it and produces nice smoke.

I would suggest a repack with fresh batting to hold the fluid.

Just an option.

Edit: I found the wiring diagram, attached, and here is the link for the mouser part that I used. Mouser Bridge Rectifier

There is no engine number in the documents that came with the polar express, or on the download at the time which is just weird, but I found the documentation from 5/05 #73-1960-250.

The Smoke Unit Assbly part number apparently #6208616200 from the pdfs that I stored off long ago when I bought it.

In combing through old my notes, Someone suggested to use a 27 ohm (PN 600-8141-055) which was used in many MPC Lionel smoke units.  Here is a picture of what it looks like.

I have to look at the PE smoke unit again to see if this type of resistor will work without shorting something out.  It may be better to use a ceramic coated one so it's less likely to short out against the smoke unit itself.

I have improved this smoke unit as far as it will go with the stock resistor (whatever it is), so I may give the above a try once I source it unless others have better suggestions.

Anyway, that's why I am seeking advice before I crack open the shell again and give it a go.  Right now I have no resistors to try out yet.

The diode idea I'm sure would work too, but there just isn't a lot of power in the smaller motor PE in the first place.  Let's just say, I don't have to worry about it flying off the tracks when pulling its 6 cars.

Paul,

You can use a 27 Ohm resistor, or even a 24 Ohm. Just make sure the positive side doesn't hit the smoke unit. What I do is install heat shrink wrap on the positive side

and make sure all of the wire is covered so it can't hit the side of the smoke unit.

Alex

Paul, Lionel shows the parts on the web, you just need to select the right engine.  The newer models shifted to 18 ohm 3W.  I have the newer conventional PE and LC PE and they both still use the mechanical puffer, but smoke much better with the new resisitor.

I have them in stock, if you don't want to pay Lionel's $9 shipping fee.   E-mail in profile.  G

I put a 20 ohm resistor in a couple of those and it improved the smoke in a big way!  You can buy them from Digikey for peanuts, let me know if you want the link to the parts.

John,

Please post the link or links with them smoke resistor candidates from digikey. Finding 3 watt resistors locally is not happening.  I can get 1/4, 1/2, 1 and 5 watts, but not 3.  I'm sure this thread will help many improve this PE smoke units.

Thanks.

Paul, 5 watts is fine (better rating) as long as it is not too bulky.  G

Actually, 5 watts is not better.  The resistor is purposely underrated so it'll get hot enough to vaporize the smoke fluid.  A 5W resistor will not give you the same performance.

Lionel units have 2W and 3W resistors, depending on the specific models.

I'd buy several of the 3W and several of the 2W, then you can try to see which one does the job the best.

Paul, here are a couple of possibilities for 20 ohm 3W resistors.

http://www.digikey.com/product...PC3D20.0CT-ND/596347

http://www.digikey.com/product...PC3D20.0CT-ND/596347

Here's a 2W resistor.

http://www.digikey.com/product...A10R0JACT-ND/3777398

I agree with John on the 5 Watts, which is the reason I didn't buy any locally.    Thanks for the part numbers from digikey, if I still can't source any 20 ohm 3 watt resistors locally, I'll order a few from digikey, and this will complete my PE smoke unit upgrade since all that was left is replace the stock resistor.

I've done this upgrade on a few conventional locomotives and it makes a big difference.  Several people came in after buying sets and told us that the smoke unit didn't work!  Actually, it did, but you had to be going warp speed to get any smoke out of it.  With the addition of the proper value 2W resistor, smoke was much more impressive.  I also add additional wick to insure a steady supply of smoke fluid to the heater.

Please explain this to me, since the heat generated is based on the resistance of the element and the voltage applied, not the wattage rating the element can handle.

I have seen larger elements in some K-line and MTH uses it in G.

Frankly for a $1 or 2 I would think it would be worth trying. G

Line them up on your bench with the same voltage on them and measure the temperature.

Ok, But according to ohmite the Watt rating has to do with peak temp the resistor can handle.  Heat is still VA, and factors such as enclosure, element spacing, airflow, ambient temp, and others factors drive peak temp leading to picking a resistor wattage that can handle it.

Airflow being the major factor that allows a smaller wattage rating despite VA much greater than 3 Watts in most applications.

All this given the 5W is not much larger than the 3W, which they usually aren't.

Hard to believe it won't smoke. You said in previous post you leave the coating on which suppress external temperature. G

Actually, I did not say leave the ceramic coating on.  I would only do that if it's a very tight smoke unit and it's likely to short against the sides.  Most of the time I use the Dremel wire wheel to remove the coating, a process that I've previously described here.

I'd agree with gunrunnerjohn - you have to test them.  All you need is a modest (20%, 40%) increase in temp rise above ambient and you should get a lot more smoke, I think.  going overboard is just going to get you really short lifetimes.  

Using a smaller watt rating might get you more heat but it will also get you shorter liftetime - typically lifetime is inversely exponentially proportional to heat: double the temp rise and you are likely to get smething like only 1/4th of lifetime, roughly speaking.  If a 5W doesn't do the job, I'd try to find a 4W, not go to a 3W, which I suspect might have a short lifespan.

Lee, Lionel uses 2W and 3W resistors in most of their smoke units.  I see very few burned out resistors.

I understand -- I think 3W at 18V is pretty standard any more.  But someone brought up 5W, and my point is that if this particular loco had a 5W resistor in it from the factory, switching to a 2W or even 3W might cut life more (but certainly would smoke like demon in the mean time!).  If it were my loco I'd go down only one notch at most: 5W to 4W, or 3W to 2W.  In particularly I would expect a smaller wattage to burn out much more quickly if you were to run out of smoke fluid - the evaporating fluid does noticeably cool the element - with it gone, well . . . stuff happens!

I've never seen a 5W resistor in any smoke unit.

MTH G Gauge and Some K-Line.

Lee the issue was that locally only 5W at 16 ohm were available. Vice the 3W 16 ohm.

Lionel has replaced the 30 ohm in the PE with a 16 ohm.  They are driving it from the board so they may modify track voltage to the newer ones, but I am not sure.

The 5W resistors I have seen are a little larger so surface area is greater so peak temp should be a little lower, how much is what is being debated.

I have seen plenty of burned elements in MTH.  Once you run them with no fan they will burn the element rather quickly.  As soon as the air flow is lost, you loose the cooling factor and you find your over the wattage rating and the peak temp limits.

Loosing the fan is easy to do by motor going bad, tether wire break, or fet damage.  It is hard to detect since folks know they lost smoke but don't realize it was the fan and not the element.  G

Looking at the parts list on Lionel.com, Lionel now is recommending for the conventional Polar Express:

691RS18OHM SMOKE ELEMENT / 18 OHM 3W WIREWOUND

Price is $4.00 plus $9.00 s/h.  I would like to find a source this open style wirewound for better than $13.00.

It looks like this:

My original smoke element was a green coated ceramic one with no numbers left on it the last time I was in there so this element will probably be a huge improvement to whatever the original was.

Check us out,

Bill

Paul I posted this 2 days ago.  I have the Lionel version in stock.  G

Here's a choice from Digikey: 3W wirewound 18 ohm resistor for 45 cents.  The great part about Digikey is you can order small quantities and they only charge actual first class shipping in the $2-3 range.

I take the resistors I get from them and use the Dremel wire wheel to remove the ceramic coating, it comes right off with a gentle touch and leaves the nichrome wire intact.  You won't find them any cheaper I would imagine.