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@Lyle S posted:

thank you sir. ordered. Now one more question. Same engine.... smoke unit, replaced complete unit, resistor heats and produces smoke but fan will not come on. i see no AC regulator on this engine. what am i missing

Catch22 pesky details...

Your engine used a 27 Ohm unit with fan powered by the smoke heat power source using an onboard regulator for 5V for the fan motor.

You said you replaced the entire unit- but the problem is, while it might look identical, it might have the same plug, some units did not bridge the heater power pin to the fan motor power source pin.

Topside view

Either you had a smoke unit with a matching trace connecting the smoke heat pin and fan power pin together


Some engines have a harness where the 3 pin connector wiring has the 2 outer pins connected together.

However, if you only have 2 wires in your 3 pin connector and use a smoke unit without a connecting trace= no fan power.


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There is a possible problem that some Lionel smoke motors fail. Many of us then replace them not with a Lionel part, but rather an MTH sourced fan motor. Again, the reason is, we find they (the MTH motor) are a better part.

Part BE0000041

MTH parts site does not allow direct part linking- however on common parts and upgrades page https://www.mthpartsandsales.c...ts/240?type=products


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Again, given the scenario, you get smoke heat but no fan, the original unit was known to be a common 27 Ohm rectangular unit sharing common heater and fan motor power, you replaced that with another (and at least to me- risk of a wrong or slightly different unit).

#1 might not be getting power into the smoke unit on the fan input power pin- either due to the wiring harness not populating the 3rd pin connector or the PCB of the smoke unit not having the trace to bridge the heater power over to the smoke fan input pin.

#2 the fan motor might jammed or failed some other way.

#3 the smoke unit PCB has a small 78L05 5V regulator- that a bad or jammed fan motor could possibly burn out this regulator, thus even though you are getting near track voltage into the fan input pin, the fan motor pins are not seeing regulated 5V output to run the fan.

Also, just to be sure not another failure- again, the R2LC (the main TMCC radio receiver board but ALSO the same processor runs all engine functions- including smoke output) must be programmed with a feature code - and a correct one for a given engine.

So- that said the engine manual found on the same product page I linked earlier from L support

Again, if you don't set the feature code or it defaults to an incorrect one- then the smoke unit output won't properly output the voltage for the smoke unit. This is because the output can be used for other things like beacon lights or other functions and while it outputs power- not enough power or slight DC bias- and since the smoke unit only used 1 diode in the fan circuit for half wave rectification- then the fan circuit doesn't get voltage but the heater DOES still heat.

So just saying, reset your feature code first- before other troubleshooting.


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Last edited by Vernon Barry

thank you so much! ive just started into this "sport" (bending, crawling, stretching) lol about 6 months ago and Ive  learned so much from these forums and gentleman like you. I try to retain all i can and help others when I can. Im the kid that tore things apart just to see how they worked but then forgot how to put it back together. So again thank you

General information:   TMCC speakers were 8ohm, may be 1 watt.  MTH speakers were 16 ohm, not sure of the watts. The corresponding sound drive boards would match.  One of the problems with the TMCC sound system, was the speaker/sound came on at full power/max sound.  Early speakers failed under full-on.  Later replacement speakers were a bit better.

Problem with both TMCC and MTH speakers,  were the fuel tank placement.  Speaker, a magnet, tended to collect metal from the track/road bed, which de-graded the sound.  IMO, Mike CT.

Last edited by Mike CT

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