Runaway TMCC Steamer

Sounds like the motor driver board is going out. Usually the engine stops when the TMCC is lost, not speed up.

I have thought of adding cruise, Would that board be replaced when I add cruise?  Don

Could be the tach magnet has imploded as well.

It seems to do it when I have other trains running.

 Is there a tach magnet if I do not have cruise?  Don

Check the antenna also, make sure the handrails are not touching the shell.

Sorry.  Missed that it was not cruise.  Disregard.

If you lose the TMCC signal and then have a power interruption to the locomotive, the second time it gets power, it'll run at full speed in conventional mode.

 

The other cause is as mentioned, sometimes the motor driver will cause that behavior.

 

If you put a Cruise Commander M into that unit, it does indeed replace the DCDR motor driver.

Tried again today and it worked fine running 4 trains.  The only thing I did was add the capacitor to the lockon on one of the new loops (loop with pullmore motor). I'm not convinced that that fixed it but time will tell.  Don

It's interesting that there's another discussion going on about Pulmotor locomotives causing problems with the new Lionel ZW-L transformer, I'm curious to see how that comes out.

 

With little or no sheilding   and exposed windings i can see where they may be more rf produced. Don

This appears to be something feeding back to the transformer, hard to imagine exactly what it is as a 10uf cap across the transformer didn't affect it.

Some of the large value capacitors have a fair amount of inductance and do not bypass high freqency well.At work we sometimes used 2 caps, one small for good high freq bypass and one larger for low freq. Don

Yep, that was just a "trial balloon", that actually solved the issue with the TMCC Direct Lockon tripping on some TMCC locomotives for me.