Restoration Big Boy 20-3807 proto 3 smoking whistle not working

Well, that board is $30, so not the most expensive thing to have fail.

https://www.mthpartsandsales.com

Vernon, Thanks for the input. I also did a search and found it on MTH's parts site. A few questions.........When I went to the site and typed in 20-3807-1 in the search box no items came up. Just wondering why? I had to type in Big Boy to see the parts listed for sale. Secondly, how would I know this is the defective board before I buy another one? Take a chance this is the bad board and just replace it? And of course..........Assuming this is the bad board, What made it fail in the first place? Is there something I did to cause the board failure? Thanks

Does the fan run on 3-5V DC? I've seen some fans run on 9V DC but not at the 3-5V the board supplies to the fan. If it's just a dead fan that can be caused by too much smoke fluid in the unit, which can damage the fan. I'd try swapping the fan motor before replacing the smoking whistle PCB.

If the smoking whistle PCB is actually dead I'm not sure what could have caused it. You'd have to double check for any wiring shorts etc.

@jini5 posted:

Vernon, Thanks for the input. I also did a search and found it on MTH's parts site. A few questions.........When I went to the site and typed in 20-3807-1 in the search box no items came up. Not all new engines have been added to the MTH parts diagrams search section. Perfectly normal and the workaround is use a more common name rather than exact product number.

Just wondering why? I had to type in Big Boy to see the parts listed for sale.

Honestly- Mike Reagan put out tons of videos and tips when the site launched explaining exactly how to use the site, limitations, and how to increase success using alternate searches. https://mthtrains.com/news/718

Excerpt from that news link:

Site

• The new site will include some tutorial videos to assist visitors in their parts ordering journey. While the site is quite intuitive, the tutorial videos are worth a quick watch prior to entering the site to ensure visitors understand how it works and make searching for parts a breeze!! You'll find those tutorials HERE.
• Please take time to explore the site. Each search function has a "broad" search and a "filter" search to help you drill down and refine the results to just the parts you need.
• If you have questions, please do NOT call M.T.H. Electric Trains, instead, email MTH Parts and Sales LLC at info@mthpartsandsales.com as this will be our only point of contact.
• Exploded view diagrams may not exist for every M.T.H. product. While the goal is to create an exploded view diagram for every product we have produced, it’s a slow-going tedious process that just takes time. If a part list does not exist for the product you have, then search the parts database. The new site has access to every part we have in our inventory.

Secondly, how would I know this is the defective board before I buy another one? It's a little hard to diagnose. This board is sort of middle board- between outputs of the PS3 boiler board normally used for lights and other functions- and then takes those and drives the whistle smoke unit both fan and heater. You would have to know both the input states and the function of the board to then check for correct outputs. I mean you tested the fan and it ran on a 9V battery, but pray tell me you heard from @gunrunnerjohn in dozens of his posts- (Edit, and Lou just said basically the same thing) that is NOT the best test for a fan motor and does not indicate it's current draw or other problems that could then in turn easily burn up a controlling MOSFET. And a failing MOSFET, first stuck on as it fails kinda sounds like your symptoms then it just dies and burns open circuit to no longer run the fan. "It sputtered out smoke at first but didnt keep sync with the whistle. After a minute, it quit completely." Again, this sorta sounds typical MOSFET first overheats and fails shorted fan stuck on, then finally burns completely out- never to run again.

Take a chance this is the bad board and just replace it? Even myself, I might be in that boat. I don't know and have not reverse engineered the board as to what output controls fan and heater, what might have a failed and so forth.

And of course..........Assuming this is the bad board, What made it fail in the first place? Likely high current draw of the motor- possibly caused by excess fluid blocking the impeller, a failing fan motor, smoke fluid contributing to the motor commutator slots getting filled with conductive brush dust- thus intermittent shorts as the motor rotates?

Is there something I did to cause the board failure? Kind of an unknown- maybe?? Again, sounds like the smoke unit was recently filled, maybe overfilled into the fan. That extra load on the fan of liquid VS air and it died with repeated attempts to keep using it.

Thanks

Put another way- at least you don't have one of the newest engines with steaming/smoking whistle (remember, the MTH name had to be different than the Lionel name for the same function). I say that because at least you have a separate $30 replaceable board controlling the unit.

On new recent ones (example the recent Heavy Pacifics, Mikados, and so forth 22, and 23 releases) all used a smoking whistle specific boiler board that is all in one. Imagine if you damage that board- with a big fat out of stock label.

Thanks to all so far. I actually did try another fan motor. Still did not work. So I am thinking I will take a stab at a new 30.00 board. I also think I should replace the fan motor with a new one. I searched 3 pages of "big boy" items on the MTH site and did not see a fan motor  (unless I skimmed past it).I am not sure if the whistle fan motor is different from the main stack smoke. Where would I find a new motor?  as always thanks

@jini5 posted:

Thanks to all so far. I actually did try another fan motor. Still did not work. So I am thinking I will take a stab at a new 30.00 board. I also think I should replace the fan motor with a new one. I searched 3 pages of "big boy" items on the MTH site and did not see a fan motor  (unless I skimmed past it).I am not sure if the whistle fan motor is different from the main stack smoke. Where would I find a new motor?  as always thanks

For O scale, there only is one motor for fan. Both the small and big smoke units use the same motor.

https://www.mthpartsandsales.c...ts/240?type=products

Since you have this engine obviously all torn apart, and you’ve removed the motor leads, yata, yata, yata, …..why not check the motor output from the board with a meter ?….then you can confirm it, ……it sure sounds like a whistle board gone bad, but a cold solder joint, broken wire, etc, can make your day bright……I’d be verifying things instead of darts in the dark diagnostics,…..😉

Pat

@harmonyards posted:

Since you have this engine obviously all torn apart, and you’ve removed the motor leads, yata, yata, yata, …..why not check the motor output from the board with a meter ?….then you can confirm it, ……it sure sounds like a whistle board gone bad, but a cold solder joint, broken wire, etc, can make your day bright……I’d be verifying things instead of darts in the dark diagnostics,…..😉

Pat

Thank you for the response. I kinda did that early on.....After unsoldering the fan motor, I put the fan leads to my meter set on 20 v dc. With FSW soft key engaged and the heater making smoke, I used the whistle button and got nothing on my meter.  I guess there could be an issue with the 3 or 4 inch leads but I doubt it. I reseated the sockets to the board a few times.  Not sure how I would get my meter leads on the male pin socket attached to the control board. If that board were good, the slightest slip of a meter lead may short the pos and neg of the fan. Then I definitely would have a dead board.

Hi the voltage cannot be read by a volt ohm meter because the voltage is pulse width modulation "PWM" you could see if you had an oscilloscope you could see the pulse. the smoke motor as far as that goes must run on 2 volts to test, if it won't run on 2 volts replace the motor!

Alan