Lionel Smoke Unit Fan

@Vernon Barry posted:

From that picture- my only response is WTF.....

It’s certainly aggravating

Look, sorry, but at some point, even if you know nothing, it's a DC can motor- tiny yes, but still DC, and still a simple motor.

The diode solder blobbed across both terminal of the tiny motor somehow doesn't seem factory to me- at best it would be flyback diode- maybe.

My first instinct is remove it and question who put it there. Take the soldering iron away from this person.

The abortion of all abortions ever posted here as picture.

if the black wire is on the motor terminal, then surely the red wire would go to the OTHER terminal of the motor that has no wire.

The support picture over at Lionel shows this and NO DIODE

@Vernon Barry posted:

Look, sorry, but at some point, even if you know nothing, it's a DC can motor- tiny yes, but still DC, and still a simple motor.

The diode solder blobbed across both terminal of the tiny motor somehow doesn't seem factory to me- at best it would be flyback diode- maybe.

My first instinct is remove it and question who put it there. Take the soldering iron away from this person.

The abortion of all abortions ever posted here as picture.

if the black wire is on the motor terminal, then surely the red wire would go to the OTHER terminal of the motor that has no wire.

The support picture over at Lionel shows this and NO DIODE

I’m the only owner of this engine…purchased brand new, so it was like this from the factory.

Step1 go to Lionel support and enter the product number.

https://www.lionelsupport.com/...-Steam-Locomotive453

From there, we have a smoke unit reference page

So I go there and can see the parts breakdown and pictures of factory smoke units

https://www.lionelsupport.com/...-Legacy-620-8312-200

The last item on the page has a picture link

No diode on the motor. Black wire on one terminal, red wire on the other- just like this

If you absolutely have decided to solder it "as is" with the diode in place. The red wire goes to the top terminal where is no wire.

@Vernon Barry posted:

Step1 go to Lionel support and enter the product number.

https://www.lionelsupport.com/...-Steam-Locomotive453

From there, we have a smoke unit reference page

So I go there and can see the parts breakdown and pictures of factory smoke units

https://www.lionelsupport.com/...-Legacy-620-8312-200

The last item on the page has a picture link

No diode on the motor. Black wire on one terminal, red wire on the other- just like this

Thank you, I have also performed these steps, prior to my post.  What I’m looking for is an underbody picture of 620-8327-200.  Can’t seem to find one on the Lionel support site.

Here's the best I can come up with for the 2 wires diagram

@Vernon Barry posted:

Here's the best I can come up with for the 2 wires diagram

Thank you. If you are recommending I not re-solder the wire, which part(s) should I try to find/purchase to rebuild the unit?

@John Ptak posted:

Thank you. If you are recommending I not re-solder the wire, which part(s) should I try to find/purchase to rebuild the unit?

I'm saying solder the wire to the point I showed you.

If I was rebuilding the unit- I would replace the fan motor- the one from the smoke unit breakdown.

https://www.lionelsupport.com/...DIAGONAL-SCREW-HOLES

Inability to solder aside, I'm fascinated to know what the goal of the diode was. I don't think I've ever seen that before.

@J.Dooley posted:

Inability to solder aside, I'm fascinated to know what the goal of the diode was. I don't think I've ever seen that before.

As I said in an earlier reply- appears to be a flyback diode.

When you spin up the motor fast, the impeller keeps spinning when you stop applying power. The motor then becomes a generator. The transistor on the control board controlling the fan typically has a maximum peak inverse voltage- and were the fan to exceed that- pop goes the transistor. The diode only conducts the reverse voltage. As wired, with the + red wire attached to the striped end of the diode cathode, the - black wire to the anode, it's as if the diode is not there. However, when the motor creates a reverse voltage from spinning down- now the diode conducts this reverse polarity so it cannot reach the control transistor.

Edit- secondary function, it may also brake (stop) the motor faster to give a more distinct puff.

Thank you for the explanation. That's fascinating. I didn't realize the spin-down of that tiny little impeller would be enough to do anything with from an electrical standpoint.

Now I want to do it and see what happens. I promise I'll try to solder better.

I use dynamic braking in the Super-Chuffer to quickly stop the motor.  In my case it's active braking, I have a FET that shorts the motor when I want to stop it.

One correction to the previous description.  When the voltage is removed, the generated voltage from the motor does not change polarity, as long as the motor is spinning in the direction it was powered in, the polarity remains the same.

Here's a quick video of a motor powered with 12VDC, then the power being removed and the motor spinning down.  Note that the polarity remains the same as it spins down to a stop.