Smoke fan not working on MTH S-2

The PS/1 locomotives have a self-contained smoke unit with the fan being driven from the same voltage that runs the resistor.  Top suspect would be the fan motor, followed by a component failure on the smoke unit PCB.  Either can be fixed inexpensively.  If you have some basic electrical skills, chances are you may be able to do this yourself.

That's good to hear.  Sounds like I need to find some time to open her up and poke around.

Yep, since you have power to the smoke unit, it's all right in one place.

John,  No quite true.  The AC power comes in and is rectified by a 1A bridge.  The bridge powers the heat element and a small IC 5V regulator.  The 5V regulator powers the smoke fan.

Sinclair, An easy test if you don't have a meter is test the fan as Luke said with battery and plug a 5V bulb into the fan motor 2 pin connector.  If the bulb lights the motor is bad.  IF the bulb doesn't light the 5V regulator is bad since you are getting heat to the element.

Don't run smoke without fan, you will burn the wick and overheat the element causing fracture or reduced performance.  G

George, I was referring to the track voltage coming in.  The fact that he's getting the smoke resistor indicates the problem is clearly with the smoke unit itself and not an external cause.  I realize that there is electronic control of the smoke resistor and fan on the PCB.

Here's the PS/1 smoke unit schematic.  There may be some component differences, given the handwritten corrections, but it's generally accurate.  I've used it to repair several of these.

John, I was just clarifying.  As you stated it, the implication was the smoke fan gets the same voltage as the Heater element, which is not true.  Just want to be sure some one doesn't think they can apply Track voltage or high voltage to the fan motor.

The additional details I provided help him isolate his testing.  The bridge is ok because the heater gets hot.  So he can hone in on fan motor and 5VDC regulator.  G

I check the fan motor first, then move on to the electronics.

We'll see if I can put some time in this week to work on it.  I do have a meter around the house somewhere.  When I found it while looking for something else (most of our stuff is still boxed up from the move) I think I put it with the rest of my tools so I could find it easily. Thanks for the info.

Okay, I took the shell off and powered it up, I got 5V at the fan (using my multi meter (MM)).  I did nice that I could here the typical hum/buzz of an electric motor trying to turn but wasn't, so I removed the 4 screws on the PCBA and pulled it up.  The fan fell away, and the board had teh wick/wad burned to the resistors, and it was really crammed in there.  It was burned to the resistors, and took quite a bit to yank it free.  I powered it up again with everything loose and the fan turned just fine.  I think the wick was jammed up against the fan impeller keeping it from moving.  That or the gasket as it was hard and bowed away from the PCBA into the fan impeller cavity.  It's also an oily mess in the front, so I'm sure it was over filled.

So with the good news that the fan is just fine, I have to ask where to get a new gasket, or make one from what, and where to get new wadding.  I might as well get a bunch of wadding since I have a couple K-Line TMCC steamers I want to do the smoke unit mod on to get visible smoke out of.  And how much wadding should I put in so that there isn't too much or too little?  And do I need to jam it between the resistors or is just under them in the bottom of the smoke unit box fine?  And what's the best way to clean the smoke fluid off?

Sometimes the impeller hole gets to large and the motor shaft spins inside the impeller.  The wick should be pinched between the to elements.

Soak up the fluid with a rag.  You can use insulating material for the wick, or strands off the tiki material for oil lamps.

For gasket material permatex non hardening gasket liquid, or purchase from MTH.

What is the resistance of the elements?  Should be 16 ohms each.  You may want to replace them if damaged.

WHen putting fan together ensure impeller is pressed in to clear PCB/gasket.  Add a drop of locktite or Super glue to the impeller hub/fan motor shaft.   G

You normally stick the smoke wick between the resistors. That's the way the stock MTH smoke units are built, and we all know how well they smoke.   I clean the resistors by soaking them in solvent if they're really bad, then using an old toothbrush on them.  For the fan gasket, I normally trim away the part above the fan blade so it won't swell and block the fan.

I'd like to find some thin gasket material so that I could make the gaskets instead of paying $9 shipping for one part when I need one.  It's not a think you'd normally keep in stock.

You can get the wick and the smoke unit gasket from MTH, but I'm guessing the gasket may not always be in stock.

John,

Gasket vellum is usually available from an auto parts store, and it cuts easily with scissors or a hobby knife. Try making a gasket template by from a photo copy of the gasket surfaces. Paste the template to the vellum and cutout the gasket.

I follow GGG's advice and use automotive silicone gasket material:

>Clean the gasket surfaces with isoprophyl alcohol;

>Butter the gasket surfaces with a very thin film of silicone, and lightly screw down the circuit board to avoid squeezing the silicone out;

>Snug the screws after the silicone cures .

If gasket material from my local auto parts store will work, I'll just go that way.  I work for a company that makes laser cutters/engravers so I can make my own exact fit gaskets during my lunch breaks (I've also toyed with the idea of bringing my rolling stock in and engraving my name on the bottom.).  What's best to clean the locomotive body with that won't hurt the paint?  As for the impeller, I know it's nice and tight because I stopped it with my finger and could tell that the motor stopped.  I think that the wadding ended up in the opening between the fluid box and the fan and pressed against the impeller not allowing the motor to move.  And judging from how burned and crispy the wadding was I'm guessing it's been like that from the factory.  The guy I got it from said he pretty much never ran it because he didn't like the sounds.

I couldn't find stuff thin enough for making the gaskets, anyone got a source?

If you can't find proper gasket paper easily, then commonly available alternatives include baking paper, or the paper from a bag of sugar. 

Did you try carburetor gasket material?  That's what I was going to try since that's the 1st thing I thought of when I saw the gasket on the smoke unit.  At one time you could get a roll of it to make your own, but that was over a decade ago when I last got some.

I'm not sure what"baking paper" is, and the stuff on the sugar bags we get doesn't look like very good gasket material.

I'll keep looking.

Well, I found out that my favorite LHS happen to have the old MTH service parts kit, that he happen to stumble across as he was cleaning the back room, so I bought wick and gaskets from him.  Last night I got it all put back together, and wow, talk about tons of smoke.  4 laps around the living room and it looked like an old time film noir smoke filled bar.

I also took measurements and drew up the gasket in SolidWorks, and then bought a sheet of Fel-Pro gasket material (Part#3157).  So sometime I'll cut a bunch of gaskets out on a laser here at work and have a stock pile of smoker gaskets for servicing my ever growing fleet of PS-1 steamers.  One of these days I'll take my Big Boy and Allegheny's smokers apart and draw up and cut some of those gaskets too.

Isn't that gasket material pretty thick?  I'd like to find some really thin stuff to make gaskets from.

The stock gasket is .021".  The Fel-Pro stuff I got is .03125".  In this case, I don't think 10 thousand over is going to hurt anything.

I'm going to have to look at that stuff, when I went into the auto parts place, all the gasket material was pretty beefy, and didn't look to be suitable.

I looked online, found an Autozone that had several options online listed as in store, and went in person.  When I said I wanted to make my own gaskets, he took me into the back to show me a folder of what they had.  He kept pulling out thicker cork stuff, so I finally "pushed" him out of the way to look for myself.  Because I looked online, I knew what I was looking for and dug around in the folder until I found what I wanted, a 1/32" thick rubber-fiber gasket for oil, water, or gasoline.  If it can handle a timing cover or distributor base like the insert says, then a smoke unit should be a walk in the park.

I'll have to look again.