Smoke fan motor runs continously

This is normal for this engine. I have it, Century Club 671, and it always runs the fan.  As far as the smoke, mine smokes great one I replaced the wicking and increased the intake hole per Mike Reagan's TMCC smoke unit improvement video.

https://youtu.be/YuCcfmSELe8

Thank you Marty.  With the fan running continuously, I only get smoke when the 9 key is held down.  Once the 9 key is released, no smoke.  Any thoughts?  Sincerely, Hank

What's your track voltage? Works best with 18 volts. 

About 18 volts, varies between 17.3 and 18.7.  Changed the batting material with the resistor change and increased the intake hole size.  Thank you, Hank

In order to get lots of smoke from TMCC equipped locomotives, I do the following.

• Replace the resistor with a 3W 20 ohm wirewound resistor.
• Replace the wick with the Lionel braided wick scrambled as per the Mike Reagan video on smoke units.
• Drill out the intake hole to 1/4", and don't forget to enlarge the hole in the gasket.  I have a 1/4" paper punch that conveniently does the gasket.
• Position the resistor between 1/8" to 3/16" from the PCB and close to but not under the stack.  Make sure there's good airflow from the fan chamber through the smoke chamber.
• Insure the fan is running clockwise, I've found a few running backwards.

Doing all that should result in plenty of smoke without going into boost mode.

Thank you Gun Runner John.  Will replace the 27 ohm resistor with the recommended 3 W 20 Ohm.  Sincerely, Hank

 Never had to change the resistor to get good smoke out of this unit. Certainly worth the effort though to get it up and running. 

You can do fine with the 27 ohm, but you'll do better with 20 ohms.  If you really like smoke, it's a worthwhile change.

This weekend since I had one laying around, I replaced the 691-PCB1-045 board with the 27 ohm resistor with a new one.  Well the smoke started and it would have set a smoke alarm off!! But it did not respond the keys to turn on and off.   Then I noticed the solder joints on the resistor were melting. So I turned the engine off.  The soldier joints solidified.  So it is time to replace the LCRU-2 board.  Thank you for all of the advice and help!!  Sincerely, Hank

Where does one get a 3W 20 ohm wirewound resistor?

Hank, you can just replace the smoke triac on that board much cheaper.

Jim, you can buy 20 ohm resistors at Digikey.  Buy this 5W 20 Ohm Resistor, place it in your vice at a 45 degree angle clamping on the corners.  Tighten enough to shatter the ceramic, you come up with a perfect sized resistor for the smoke units.

So what is the "math" for the resistance and wattage on replacing the 27 ohm resistor?

18v AC track power, 9v AC (I think)at the smoke unit...

It's a little math and a little "seat of the pants" experience.  The wattage is pretty universally in the 2-3 watt range, and you're looking for 5-8 watts of power dissipation in the smoke unit.  In the simplest form, the input to the smoke triac would be a pure sine wave.

Consider 18 VAC sine wave from a transformer.  The P-P voltage is 1.414 times the RMS value of 18V.  So the RMS value of the half wave computes to 12.726 volts.  In general, I consider the smoke resistor to be receiving 12 volts and work from there.  However, that was really only the starting point.  My real limitation with TMCC is the smoke triac on the R2(4)LC board.  I tuned my resistor calculations to the triac running at 75C or less after a few minutes of running.  That ended up being 20 ohms at 18VAC input to the locomotive.  If you use 12 volts and 20 ohms, you compute .6A through the smoke triac.  I'm assuming the triac drops .7 volts in half-wave operation.

The problem is, most modern electronically controlled transformers don't output a pure sine wave, so the computations get a little more complex.  That's where the seat of the pants comes in, but I'm still using 20 ohms as my self-imposed minimum smoke resistor value with TMCC smoke units.

On the locomotive in question, the voltage  at the resistor is about 8.5v AC and about 16v with the "boost" button.  It never smoked well (pathetic actually) to begin with.  Based on the numbers above of +/-12v, I'm wondering if have an output problem with the R2LC...

It's not the R2LC, most cheap voltmeters don't read non-sine waveforms all that accurately.  I get the same numbers with a $10 voltmeter, but my 'scope shows me that the R2LC is behaving properly.

Drill out the intake hole, enlarge the stack hole as much as possible, replace the wick with the Lionel wick, and install a 20 ohm resistor.  Make sure the resistor is from 1/8" to 3/16" spacing from the PCB, and it's close to, but not under the stack exhaust.  Insure there's airflow from the fan chamber to the stack, and it should smoke great.

Thanks.  

I'm starting another post on mutimeter questions, oscilloscopes, etc...