Hi, this is my first post as a member from over the pond!

I have a US O scale DCC layout that I exhibit in the UK.  One of my locomotives is an Atlas "Pennsylvania" RS-1 that had a Lionel TMSS system. 

I am part way in the process of converting it for DCC use: have (carefully) removed the TMSS and installed DCC with sound.  Electro magnetic couplers have been replaced with standard Kadee 740s.  I found the article by Gene Clements (O Scale Trains, Sept/Oct '07 very useful).  I am now at the stage of attempting to use the TAS AC version smoke unit. 

I am looking for some guidance, if anyone can help.  I have searched for posts about this but none seem to match my requirements.  The photo below shows the Trains America Studios AC version - I have annotated it to help with replies:

1.   There are two red/black connect points A & B - can anyone help as to which would be the track feed and which could be the connect point for a DCC function;

2.   The smoke fan motor C seems to have no obvious electrical connection - fan will rotate when wires are applied to the base of the motor (3rd view C).

3.   I am trying to work out what "??" connects to?

4.   It would also be useful to know if my proposal is feasible?  By the way, I have an ESU decoder Tester that I am hoping to use, pre-installation, if that's possible.


Any help on any of the points would be appreciated, e.g. ideas, links, manuals.

Thanks for reading this.



Images (1)
Original Post

Here is a look at the (EOB)  control board.  Note the (4) wires to the smoke unit. There is a low fluid level (??thermistor??) as part of the smoke unit to inhibit smoke resistor burn out.   There is only one track feed AC to the board.   Depending on how the mother board was programmed, there were different functions/voltages.

TAS turbo smoke unit.   From the resource section of Legacy TMCC control


Last edited by Mike CT


Thanks for diagram - unfortunately, my TAS motherboard differs slightly, it is a ver. 1.5 and has only 3 pins versus the 4 in your board.  However, it is not a problem as I will not be using the motherboard.

Thanks also for the link to the Turbo Smoke pdf file: it has told me that connect B relates to track feed to the heater element and I now know that good practice is to have an on/off track feed arrangement.  I guess it could either be a simple on/off switch or a DCC function to control a relay (I'm told I need an AC Solid State, Zero Crossover switching relay!!).  The heater element works.

I think I now need to work on power to the fan motor terminals C, which oddly had no wire feeds and does not seem to have any other feed via the circuit board.

Thanks again, for your assistance.




The wires labeled B are power, pin closest the smoke bowl is AC hot, pin in the middle is AC Ground. The 3rd pin (furthest from the some bowl) is chuff input, which is not used on diesels.

Not sure what A is connected to, assuming +5VDC from the regulator and ground? If so, these go to the fan motor. 

The question marks were the fan motor, but requires the chuff input to work properly.

hope that helps!


Thanks Mike.

So that helps to rule out"??".  Now, I have the heater element warming and, with A wired to the fan motor, a working fan - all from the track feed B connection.

Not sure what voltage is carrying through to the motor - will have to measure it.


Just an update re the resurrected Lionel/TAS Smoke unit - for proposed use with DCC systems.

1.   Research now completed and a test-bed has been created using ESU Decoder Tester - see (very short) mp4 video below.

2.   Smoke unit heater element connected to DCC input connector on ESU test-bed; have cannibalised the Atlas loco's Variable resistor unit to permit variable fan control.

3.  The heater unit draws requires 10.7 volts and 1.08 amps; the heater fan 4.95 volts and .10 amps.  The video shows a piece of tissue lifted, verifying the exhaust effect.

4.  An AC Solid State, Zero Crossover switching relay, controlled via a DCC function will be used to start/stop the diesel exhaust system (not yet acquired).

Many thanks for your assistance.



Videos (1)
DCC_TAS_Smoke _Unit_Test

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