TMCC F3 A-A Set Erratic Speed Control

Mark does it perform the same way under transformer control?  I presume you have measured voltage across the tracks to make sure its constant. Or you have run another TMCC engine as another check?

Its as if a capacitor is charging slowly and then exhausting itself, recharging and discharging again, creating the jerky motion. I wonder if the red wheel is having contact problems in the first 1/2 of the turn. Any way to clean the contact on the handheld? Just thinking out loud. Of course if another engine performs correctly, it falls back to that engine. Seems too regular to be a loose connection.     

Maybe it's me, but the Lionel 6-14565 set seems to have only one powered unit and one dummy unit. Is that an issue ? Not sure how you have them programmed but it almost seems like one unit is working against the other until the speed gets high enough to overcome whatever is holding them back.

Is anything binding, brake shoes, etc. ?

Baltimore & Ohio TMCC F3 Deisel A-A (PWR A #115, DMY A #115A) (lionel.com)

Mark - I had a similar problem with a Lionel Canadian National F3 AA set several years ago and Mike Reagan (the one and only) ultimately determined that the problem was because the encoder wheel was loose on the flywheel (and fixed it for me too). Don’t know if this is any help to you but thought I’d mention it anyway FWIW.

Good Luck in getting your problem resolved!

Thank you, Jeff and Richie!

Richie, you are correct there is only one powered engine.  I uncoupled the two and ran the powered one separately.  It reacted exactly the same way as in the video.  I did not see anything that could be binding on the exterior.

Jeff, no it does not react that way running with transformer control.  I forgot to mention the current draw in my initial post.  It draws up to 2.6 amps when it is moving and .6 amps when at rest.  The voltage drops 2 volts as well.  When it is running smoothly at speed, it draws just over an amp and the voltage drops one volt.    I checked another TMCC engine, and it runs fine.  Excellent speed control.  I'm going to take the shell off and look inside, maybe something is binding in there after being shipped. 

Thank you both!

@PH1975 posted:

Mark - I had a similar problem with a Lionel Canadian National F3 AA set several years ago and Mike Reagan (the one and only) ultimately determined that the problem was because the encoder wheel was loose on the flywheel (and fixed it for me too). Don’t know if this is any help to you but thought I’d mention it anyway FWIW.

Good Luck in getting your problem resolved!

Thank  you, your message came in as I was typing.  I'm going to take a look at the flywheel, maybe the encoder got loose in transit.  Mike is the One and Only! 

Since this was made in 2003-2004, it would have the dreaded Odyssey magnet sensor instead of the plastic ring.  The magnets have been known to come unglued, and even break into pieces and fly apart during operation.  If the loco got jarred in shipping, that might have been enough to dislodge the magnet or sensor.  Good luck and let us know what you find!

Thank you, Ted, PH1975!

Ted, Bingo!  That is just what I found!  I saw the magnet was sitting low and was able to hold it up with my thumb and finger for a few seconds at a time while the engine was travelling.  The engine ran correctly when I was holding the magnet up.  I have never seen this arrangement before.  Now I just need to glue it back in place.  I'll report back how it works out.  Thank you!

That's a common issue.  You're lucky that you got to it before the magnet got cocked on the flywheel and the imbalance broke it.  I've replaced dozens of these over the years, I keep a bunch of magnet rings in stock.