MTH Big Boy 20-3414-1 smoke issue

you probably added the smoke fluid to fast and you got air bubble in the smoke stack. you can try to blow with your mouth a fast hard blow and it might clear the smoke tube. when you stored it away did you put any smoke fluid in the engine prior too storage. did you try the engine on with  dcs at the highest smoke setting ,is your fan running when you turn the smoke unit on with remote! how many amps does the engine draw  when smoke turned on. should be around 1 to 1.4 amps? also sometimes when the engine sits for a long period of time the smoke fan does not spin, in that occasion you can sometimes give the impeller a small movement with something tiny enough to move the fan and it will take off , if that works Then i would either change the smoke fan or try a small drop on oil on the impeller shaft side by removing the impeller and 1 drop of oil on shaft and then reinstall impeller being careful not to press the impeller all the way down or it will bottom out and then can turn without backing it up a tiny  bit!

Alan

Yes, a simple air bubble can do that. Just clear it first. Happens all the time to me when I add a lot of fluid after sitting.

If you had a lot of smoke settling over the stacks, it is not a bubble in the stack because the smoke wouldn't come out at all past the bubble .  I would think that your fan is not running to push the smoke out of the stack.

A common issue with MTH smoke units is the impeller starts slipping on the shaft.  This is because MTH uses dynamic braking on the motor to better define the chuffs, the abrupt stopping eventually loosens the impeller.  You can also turn off the sound and listen to see if you can hear the smoke motor pulsing with the chuffs.

Question:  Does the smoke come out more normally stopped at idle?  Since there's no starting or stopping, usually the loose impeller is able to get up to speed and act normally.  If that's the case, it's likely the impeller.

Thank you all very much for your responses!

I have the smoke unit accessible to remove the cover, motor, etc., but would like to try something first: apply voltage to the motor to see if it runs.

In the picture below, which is the positive wire (within the red circle)? I imagine that it would not hurt to get the polarity backwards just for testing, but easy enough to ask. Also, what voltage should I use to test it?

Thanks!

Alex

A 9 volt battery works fine for testing, just be sure to disconnect the smoke unit before applying voltage. Failure to do so will damage the board.

Wrong a 9 volt battery will destroy the fan motor only test with 1.5 to 2 volts and the motor must start by itself or you need to replace it. the motor is only cost $6.00 plus shipping from mth! as far as testing the motor the polarity does not matter for testing only makes a difference when you install a new motor you want to hook it up the way you found it ok otherwise the draft will be in the wrong direction! the fan motor runs on five volt pulses when running!

Alan

if you need the fan motor or impeller let me know I have them in stock motor $6.00 plus shipping.

https://mthtrains.com/part/be-0000041     fan motor

https://mthtrains.com/ai-0000019 impeller $2.00 pus shipping

Alan

p.s. be glad to help you let me know? I have them in stock

Momentary application of 9V won't kill the motor, but it's also not a very good test.  If the motor won't run on a couple volts DC, it's time for a replacement.  As others have said, clearly you want to unplug the motor.  I test motors with 1.5V from my bench supply, if that doesn't spin them, I replace them.

Gray is the positive lead, but it doesn't really matter if you're just trying to see if the motor runs. 

      Alan Mancus:                                                       Looking for a alternative supplier of Mth parts   I assume you sell other parts like tires     dbrodmerkel@optonline.net

I use 3 volts DC to check the fan motors. Be sure you unplug the fan from the harness before testing it. You will cause damage to the board if you don't. You can also check the resistance of the smoke motor while you're at it. Should be around 12 OHM. 

If the smoke fan motor checks out fine then it could be a board issue. In that case talk to John, George, or anyone else who does component level board repair. 

Lou1985 posted:

I use 3 volts DC to check the fan motors. Be sure you unplug the fan from the harness before testing it. You will cause damage to the board if you don't. You can also check the resistance of the smoke motor while you're at it. Should be around 12 OHM. 

If the smoke fan motor checks out fine then it could be a board issue. In that case talk to John, George, or anyone else who does component level board repair. 

I tested the motor with 1.6v, and it runs fine.

Alan, John, George, et al.:

Before I assemble everything back together, is there a way that I can test the board to see if it provides the necessary output for the motor?

Thanks!

 Alex

Oh boy, I sure hope you tried to just blow air down it first. I have seen smoke come out the bottom because of a simple air bubble. I believe the air flows reversed, but hey! I'm no expert here. I only have 100 engines that I service myself.

 Of course the blade could be loose. That's never happened to me yet.

You could blow the fan output on the board. That happened to a PS3 board install of mine.

You can overpack the smoke unit with wick and block the hole. I've done that too.

are u sure the impeller is tight on the shaft so it will not slip. also there is the possibility that you moved the impeller like  suggested and it was stuck! if it starts on its own with 1.6 volts as  I said it will work as long as you have voltage on the motor from the electronics board ps 2 3 volt board , if  a FET has failed  on the smoke fan control there wont be any voltage . the smoke is driven  from the PV positive voltage and the fet grounds the circuit to turn on the smoke fan motor. you can have the board tested in a ps2 test fixture if you have an ASC tech near wear you live. or if you have a 6 volt grain of wheat bulb and connect it to the wires that would have gone to the smoke fan motor BUT DON'T LET THE WIRES TOUCH together or you'll blow the board! only hook the 2 wires to light bulb and void short no matter what! if you lived somewhere near me in new jersey I could test your board!  

Alan

Engineer Joe - I have a bulb that I use to blow down the smoke stacks every time I add fluid to the locomotives. I did that even after a generous amount of smoke came out of the stacks, but just settled there. I do not believe that was the problem

Alan - I am not sure how tight the impeller is on the shaft, and I am hesitant to power the motor while carefully blocking the impeller, as with a slim piece of paper, to determine if it slips. I can measure the output of the board (to the motor) with a voltmeter or with a scope, but not sure how to power up the board.

Alex

Alex,

I fire it up on a test track with the smoke unit supported on the bench.  Then you can measure the voltage.  However, if the smoke unit fan runs and doesn't draw more than round 40 milliamps, and it won't run in the engine, I'd be looking at wiring or the smoke fan output circuit, that FET may have croaked.

Alex sent you an email contact me and I will help you. 

Alan

Ingeniero No1 posted:

Engineer Joe - I have a bulb that I use to blow down the smoke stacks every time I add fluid to the locomotives. I did that even after a generous amount of smoke came out of the stacks, but just settled there. I do not believe that was the problem

Alex

Ahhh do you have to humble me so much! 

So do what the techs say and test it in the engine. You can hear the motor run usually if you shut off the sound. If you hear it run and get nothing, I'd say the blade has slipped. I've never seen that but it's a well posted problem.

If you don't hear the motor, the motor FET has popped.

(& If it now smokes, blow harder next time! )

Be very careful you do not ground the smoke fan motor to the chassis, that will cause immediate damage to the PS-2 board.

You can use a 6V bulb to test the smoke output plug.  Just plug the HL bulb into it.

Your unit looks like it is sealed pretty well. Is there a black gasket between the smoke housing and fan housing?  You can drop the back two screws to get the fan housing off without effecting the heating elements.  Just make sure gasket does not stick to fan housing.  Use razor to keep gasket on the top.  If impeller comes off easy, that is your issue.  If you pull with tweezers and it does not come off, that is not the issue.  G

GGG, et al -

I tried to pull the impeller with tweezers as suggested, but all I could feel was the slight end play of the motor shaft; the impeller is secure.

Since the motor ran fine with 1.6V, I am going to reassemble everything and try it. Will report later . . .

Thanks!!!

Alex

Check for shorts or opens from the smoke motor to the board connector.  If the fan motor is good and doesn't draw too much current, that's the next place I'd look.  If you open the tender shell, you can do an end-to-end check of the wires to the smoke motor.

Success - it works now!

I get a nice (upward) stream of 'steam' from the front stack, but only lingering 'steam' from the rear stack. Nothing from the bottom of the loco, though.

I blew (with a rubber bulb) down the rear stack, and this appeared to make it better (or just wishful thinking?), but definitely not the nice and forceful upward steam as from the front stack. It is as though something may be plugged up; but before I take it apart again, what should I be looking for?

Thanks again!

Alex

Not really surprising the stacks aren't balanced, that happens a lot with dual stack locomotives.  The only thing in the path is the smoke funnel, so if anything's blocking it, it's right there.

I have an Allegheny 2-6-6-6 (MTH  30-1612 ) and a Northern 4-8-4  (MTH 30-1601 ) both double smoke stacks.   I was able to balance the output of the two simply by inserting a good toothpick or a spraycan extension tube into the top of the fluid hole and and moving the wick inside around a little.

The wick is wound around the heating element and seems to be bunched up in certain areas inside the smoke housing.  Trial and error and a pinch of patience did the job. 🤔

Don't use the plastic spray tube if you have been using the smoke unit as the heating elements are in the vicinity of the main stack opening.   Anything that would be a little flexible but non metalic should work. 

Other than the wick arraignment there could possibly be some kind of manufacturing miscue on the inside of the double stack opening but that would require removing the boiler casting from the chassis to make an examination 😮

I just watched one of my YouTube videos (below) of the locomotive, when it was rather new (early 2014), and the smoke output was as it is now. I will see if attempting to move the wick around helps, but if not, I will let it go as it is.

Thanks!

Alex

The layout was three years old in this video, and I have 'improved' it quite a bit since!

Just watched your 3 year old video .

Observation  ONE.......

When the Big Boy was coming out of HIDDEN  PASS  MOUNTAIN  AND  ENTERING  MADERA  HEIGHTS as well as some other areas of travel   the  high output smoke from  both stack openings looked pretty good  Alex.

Observation  TWO......

 I've seen many layouts on the' Tube'    🤓 ......   Pretty fantastic looking layout YOU had there 3 years ago.  And  IMPROVEMENTS since then !!!???🤤

Really nice work Ingeniero 

I've done some tapering inside of the funnel for dual-stack locomotives to aid in balancing the smoke.  It's really a trial-n-error procedure with careful application of files and Dremel tools.

Dallas Joseph - Thank you for your kind comments.

Well, (or not so well) the smoke from the stacks stopped after a few minutes of operation. I again disassembled the engine to gain access to the smoke motor, and it still runs fine; hence, it must be the output from the board. I have the disassembled loco on the track and ready to power it up.

John, Alan, George -

Q1: I cannot find a 6v bulb to test the output of the board. Can I use an LED with a 200-ohm resistor? (I can't remember the output voltage.)

Q2: Does the tender have to be coupled (connected) to the engine for the test?

Thanks!

Alex

Q1: Yes

Q2: Yes

The gray lead to the smoke motor is positive, the green one negative.  I'd put a load on the output, say another 220 ohm resistor directly across the smoke motor connection, then use a bulb or LED to test the output.

FWIW, I'd suspect wiring/tether, normally the smoke motor FET either works or doesn't work.

Alex , John is possibly on to something here.

He mentioned a possible problem i had with wiring at the 12 pin connector .  The one with the scramble of tiny wires .

I had a problem with a loss of ditch lights on a proto 3 Premier Gp38 diesel .  I finally traced it down to  a wire separated from its pin at the  connector.  The wire  insulation showed no problem but a little wire wiggling made me get the VOM out .  Showed a loss of continuity. 

I removed a wire with the correct pin from a defunct unit and soldered it to the original wire .  Ditch lights worked at the completion of the job.  I rerouted the longer repaired wire away from the rotating motor housing just in case that was what caused tension on the wire and separation from the pin.  🤔

First, I assume this engine has the PS-2 3V board in the tender correct?  Is it using a 10 pin tether or drawbar?  Do you have access to a transformer with current reading like the Z-4000?

What I typically do is start up engine conventionally with smoke off and see the current reading.  Lets say .3 to .5amps.  The I turn smoke on.  Amps jump to 1.0 to 1.2.  I know I have heat.  That isolates to bad wick or smoke fan.

Frankly, you can unplug the headlight and plug into smoke fan plug.  Mentioned that quite a few post ago.  Or borrow the tender reverse light.

20 minutes is a good long time, did it run out of smoke fluid?  Did you blow through stack after adding fluid?

This is either an intermittent wire issue, or smoke stack getting plugged up.  IF wick is burned, output will drop significantly.

Solder joints crack under heat shrink of the 2 pin molex, wires pinched.   PCB joints crack at back of engine or tether wires break.

If markers stay lite and speed control/chuffing stay your 5V wire is good.  IF fan is running, the green return for fan is good.  If lights are on PV (positive voltage is good) which only leaves brown smoke element return.  I doubt this is a board FET at this point.  G

why not just change the wick sounds like everything else has ben covered . only other thing could be a bad cold solder joint like, was mentioned not much else it could be!

Alan Mancus posted:

why not just change the wick sounds like everything else has ben covered . only other thing could be a bad cold solder joint like, was mentioned not much else it could be!

Good idea, but since smoke was coming out in high volume, and it did work fine for a while as I mentioned above, I did not think it was a wick problem. 

Anyway, I proceeded with the recommended test for the board output. I did not have a connector to match the white connector from the board to the motor, so I modified a servo connector (from my R/C days) by cutting off one of the outer contacts, and this worked fine. I used a 220 Ω resistor and an LED, and with the loco and tender (properly coupled) on the track, the LED lit when the smoke was turned on by the remote. Then I connected the actual smoke unit motor and heater while these were out of their proper location, turned the smoke on, and it worked. 

I ran the engine around the layout for a few minutes, back to the turntable and its stall, and ended the test.

Thanks to a for your help - again.

Alex

So, I ended up here with the smoke from the bottom bit (not consistent, I didn't know about air bubbles, need to test), but ended up with a different question!!

Just exactly how much train can the mth 2-6-6-6 premier pull? The train being pulled by the big boy above, solo, was LONG!

Thanks!

My new 2 rail MTH Bigboy seems to be power hungry. I normally run my mainline using Lionel PH180 bricks at 18 volts. I had to raise the track voltage using my Z4000 on the main to get smooth running out of the Bigboy with the smoke on. When the smoke's off, the engine runs much better.

I'm having issues with this engine and haven't pinned them all down yet. I'm just thinking that it produces higher smoke volume, and maybe they used an extra smoke resistor? I hate pulling apart a brand new engine that is working. The issues seem to be growing so I'll have to do it soon. When I do, I'll look closely at the smoke unit to see if there's some change?

Maybe it's just a programming thing in the sound file to produce more smoke using more power?

I'm also looking at what's causing missing chuff issues. I'm thinking there's too much power draw thru a given pickup. I've seen that before with my one gauge Triplex melting a printed circuit board for power pickup handing. I've added wipers to other O scale engines to help smooth out power problems.

Anyways.... you may find like me, that this engine is a power hungry beast using the smoke. Maybe it's just mine?

@Engineer-Joe posted:

My new 2 rail MTH Bigboy seems to be power hungry. I normally run my mainline using Lionel PH180 bricks at 18 volts. I had to raise the track voltage using my Z4000 on the main to get smooth running out of the Bigboy with the smoke on. When the smoke's off, the engine runs much better.

I'm having issues with this engine and haven't pinned them all down yet. I'm just thinking that it produces higher smoke volume, and maybe they used an extra smoke resistor? I hate pulling apart a brand new engine that is working. The issues seem to be growing so I'll have to do it soon. When I do, I'll look closely at the smoke unit to see if there's some change?

Maybe it's just a programming thing in the sound file to produce more smoke using more power?

I'm also looking at what's causing missing chuff issues. I'm thinking there's too much power draw thru a given pickup. I've seen that before with my one gauge Triplex melting a printed circuit board for power pickup handing. I've added wipers to other O scale engines to help smooth out power problems.

Anyways.... you may find like me, that this engine is a power hungry beast using the smoke. Maybe it's just mine?

Joe the smoke unit elements and fan use huge amounts of power.

I tried to work out issues of erratic running when working with GRJ with a ps2 and ps3 Challenger and finally ended up with the fact that the smoke units use humongous power to perform.

  Make sure no other power hungry things are in use at the same time.......dirty wheels or tracks ......tight clean electrical connectors......no incadescent lights ........no passenger trains or cabooses with non LED lights........ETC.

Using the Z4000 you should be able to tell the difference when the smoke unit is on or off.   If you are using the Full DCS and remote ,is there a difference between the different smoke needs ( min, med or max ) ?

Hi, I had to send my Railking back for smoke issue…It was a failure of the wicking.

it is fine now…

Rich

from memory, the smoke settings of medium and high seemed to draw near the same. The "low" smoke setting seemed to help. The engine ran much better with the smoke off.

I cleaned all the wheels and did general maintenance. I was trying not to take her apart yet.

The chuff sounds seem to still skip slightly still, so I have to go further. Maybe it will break totally so I can find the issue easier?