Smoke Unit repair help MTH Pronto 1

Are you sure the impeller is spinning, or there isn't too much wading in the smoke unit?  Not only do you have to make sure that the fan spins, but that the impeller is tight to the fan shaft, and that the wading isn't in the fan chamber keeping the impeller from spinning, or that there is too much wading that the air can't move through the smoke chamber and out the stack.

If it were me, I'd take the whole unit off of the shell and hold it by hand to the frame and test sans the shell to make sure it is working, and smoking.  I had a PRR S-2 (30-1149-1) that I got nearly new last year that didn't smoke.  I took it apart and after doing some troubleshooting figured out that the wading had been packed wrong at the factory so that it was pocking into the fan chamber keeping it from spinning.  The wading was very black and very hard, and took a while to clean off of the heater.  But it smokes like a champ now!

If the fan motor buzzes and doesn't spin, my guess for a PS/1 smoke unit is a component failure on the board.  The smoke unit for PS/1 is independent, it just connects to track voltage.

You can take the smoke unit out and run it on the bench, it simply requires AC from 6 volts to 18 volts.  You can also unplug the motor and run it on 3-5 volts DC and see if it spins that way.

This is the smoke unit you have, right?

Ok the IC1 D restister next to the fan housing handles the fan...at times they go bad..

The "D Resistor" is really a voltage regulator.   However, they normally would fail with no voltage out. 

had one made my fan acted up..replaced the resistor and bingo..

Thank you all.  John and Josey.

Yes the Fan motor is dead, checked with DC power.  Does anyone know that part number from MTH?  Also what is the smoke wick part number too?

I replaced with a working motor from another Loco and it did not work on that board.  So also the "D Resistor" must be bad?  I have an electronics store near by that has rows and rows of parts.  Do I just ask for a "IC1 D Resistor" and they will know what I am asking?

Thanks

Mark 

One of the MTH experts will know the part numbers for the motor and wick which are order-able items.  If a known-good motor did not work, then IC1 is a good candidate for change.  You will almost certainly see the characters 78L05 as shown below somewhere on the device markings.  This is the relevant part number if you go to a store.  They may try to cross-reference this to the NTE977 which is a private-label equivalent that many electronics stores carry; this would be fine.  I'd guess about $1 each at a bricks-mortar store.  You can get the 78L05 on eBay 4/$1 (search "78L05") shipping included but it will take a few weeks to get them from Asia.

digitkey has them..Gunnerjohn knows the part number..he should cime in with part number...i need too order some more up...there fast on there shipping..

Fan Motor: BE-0000041

Smoke Wick: AA-0000001

The 78L05 is 44 cents at Digikey, they have very fast and cheap shipping for small orders.  Typically, I spend between $2 and $3 for First Class shipping on small orders.  If you come up with a few common parts you might need, you can save money on the shipping, as you get quite a lot for the same small shipping charge.

Also check the rectifier that is not cracked. (Square doo-da with 4 leads). I have replaced a few bad ones.

but if his heat elements are working then its not the rectifier..that IC1 resister is the most comon part thats goes on those mth smoke units..but just in case order acouple of them too..think id ordered 4 of them and 6 IC1 resisters..

Mark, I have the motors, element, gaskets, wick and the component parts for the PS-1 units in stock.  You can contact me via e-mail.  You can get all in one shot, with less shipping then MTH.

Or if you have a good LHS near you they may have all this in stock.  G

THank you all.  Very helpful.

I stopped at my local electronic supply and they are out of stock and D resistor is national backorder.  So I will try Digikey.

Thanks again,

Mark

John

When I searched 78L05 I got a long list of parts with many differnt letters after 78L05.

Is this the correct part 

it is .44 cent.

thats it!!....start ordering some..that what im doing..

Note that my previous post had a hot link for the part that takes you right to the correct part.

THanks John I missed it.  Wow that is easy.