Smoke unit not working

You don't need to change the smoke unit, and that would be a significant mechanical undertaking.

The symptoms suggest that it's in the smoke unit itself.  Either the smoke motor has quit, or the 5V power supply on the smoke unit has crapped out.  Neither are expensive or that hard to fix.  You will have to open it up to do a little diagnostics.

You are still hearing the chuffing in the audio, right?

Hi John. Yes. I still hear the chuffing in the audio.

That's a good sign, it's likely a simple failure within the smoke unit.  If the heater is getting hot, the regulator is working, so that just leaves the smoke unit.

So I just need to replace the smoke unit?

Note I said 'Likely".  Also, replacing the smoke unit isn't necessary, you can rebuild them as easy as replacing them.

Ok. So what do I do? Please keep in mind that I am nowhere near your experience level and I need a bit more guidance. Please.

You are out of luck replacing that exact smoke unit. Lionel parts show it as unavailable. https://www.lionelsupport.com/ReplacementParts. Part 86.

If you are good with soldering you can possibly repair it yourself. If not then you need to send it to someone that can. I can test the smoke unit or John or any other Lionel Service tech. The smoke unit might not be the problem. Read on.

If the smoke element is getting hot but the fan not running you must determine if the fan motor is working and if not, determine if there is 4.5 to 5.5 volts going to it. To do this unplug the smoke motor leads from the board and measure the DC voltage across the two pins that the motor plugs into with 12 volts ac going to the three pin plug.  AC Hot to the outer pins and ground to the center pin of the three pin plug. It is best to have the smoke unit removed from the engine and powering it up though the three pin plug using a plug made up and plugged into it for testing.  If you try this with the three pin plug plugged into the engine wiring using power from the engine and you short out the outer pins to the center pin on the three pin plug, bad things can happen.

With this test if the element gets hot and you have 4.5 to 5.5 volts across the two pin plug the motor is bad. If no voltage across the two pins you will need to replace the Voltage regulator on the smoke unit board. It uses a LM78L05ACZ, TO-92 case 5 volt regulator. If the smoke element does not get hot with the smoke unit plugged in then you may have a bad smoke switch or possibly the R2LC board needs to be replaced. It might also be something as simple as a broken wire connection.

This is why a novice should not be trying to make these repairs unless you have experience doing this kind of work. Make the wrong move and bad can go to worse in a heartbeat. Good luck.

Forest

Since he says the element is getting hot and the smoke just isn't being moved by the fan, my top suspects are the motor or the regulator circuit on the smoke unit.

It's remotely possible that the chuff signal isn't making it to the smoke unit, so check the integrity of the wiring and connector.

John; I am sure you get more of the modern Lionel engines in for service than I but this is a little confusing.  I took another look at the parts diagram. The parts list says this engine has a Semi-smart smoke unit. Lionel service manual wiring and description shows Semi smart smoke unit not using an AC Regulator BUT the parts diagram shows the engine having one. Your diagram is for a Smart smoke unit. So the next question is which Smoke unit does this engine actually have? Can we possible get an actual photo of the smoke unit here that is being worked on? Specifically the top of it.

Forest.

9th part on the listing for this locomotive 691ACRGE01 AC REG BOARD / GENERIC

The 8 ohm smoke unit REQUIRES a regulator.

From the diagram you looked up on Lionel.  That is the AC regulator.

Yes, it does list the regulator. It was looking at the smoke unit be listed as semi-smart. I totally over looked the fact that it is 8 ohm. I stand corrected.

Forest

No problem, I normally sit corrected, it's more comfortable.

Do either of you guys live near northern NJ? You guys know your $#@!, but I don't. I'm feeling a little scared tackling this kind of job. Are either of you Lionel technicians?

Ok. That was a stupid question. Of course you're technicians. I mainly want to know if you are open for business. So to speak.

Hi John and company,

By coincidence I have the exact same NKP Berk, and I have a plan to use your idea of an MTH smoke unit as the OP. I recently did the same thing to a Lionel 6-38096 PWC 773 Hudson. I LOVE the results! My only tiny complaint is that the 773 has constant smoke as soon as it starts to move. From this diagram you provided, can I power the MTH unit with the top two wires on the “smart smoke unit” and get chuffing smoke? On the 773 I believe that I’m using the bottom two wires, as I know I tapped into power from the on/off micro switch. Will I damage any electronics if basically I’m not using power from the AC regulator?

To add.... Here are the two smoke unit boards I’m swapping. Both boards have two pin molex for fan motors. The MTH board has a 2 pin molex for incoming power, but the Lionel has 5 pins. 

To the OP, note how the mounting holes by the elements for both the Lionel and MTH are in the same spots! For the 773 I mentioned above I only swapped boards. No major surgery. The MTH has two elements and a different type of fluid wick on their board. I only guess that this design difference makes (IMHO) the MTH part work better than the Lionel.

There's no easy way to tap into the electronics that way and get the MTH unit chuffing. The MTH PS/1 smoke unit you have just takes track power and produces constant smoke.  There's no provision for controlling the fan either internally or externally, it runs whenever there is power to the smoke unit.

Actually, what you seek is the very reason I designed the Super-Chuffer II, it's purpose built to solve this problem.