Lionel Legacy Smoke unit seems to be tripping my breaker, but only when shell is on - SOLVED

In your second picture I noticed a scrape mark where that black wire is on the smoke funnel is that getting pinched? 

Doug

Would tend to agree that a wire must be getting pinched that is shorting out. G

Thank you for the suggestion folks. I didn't think those fan motor wires were hitting anything, but I will tape them both to the top of the shell tonight and see what happens.

I think I'm going to take this to my LHS and let the guru there take a look. I'm at a loss here. I have taken down the smoke unit, inspected it, remounted it. taped over any wires that could be causing the short. I can't find anything that it is triggering the short with the shell on. That smoke unit does rest on that bed of wires in the middle, but I taped all that up before and it still did it.

I do appreciate all the help!

I had a problem in the Vision line Gen where one of the screws securing the smoke resistor lead touched metal on the shell. It caused much of wiring to cook. I recreated the wiring by ordering many different harnesses from Lionel using parts of them as needed. I don’t remember exactly how/where the screw was positioned but may be similarly mounted in your non Vision model. And just takes a little pressure to cause the short.

I've only been in a couple of VL Gensets.  One thing I noticed is that the boards are insulated/protected.  The vertical board where you plug your smoke unit harness into does not have protection on the back side.   Below is a pic of a VL with the similar board protected.  Maybe that is how you are shorting/grounding.

I've got the KCS version, never had any issues with the smoke unit. One thing to check with a multi-meter is to see if there is any continuity on any of the pins to the shell of the engine. It could be possible that one of the leads for the smoke unit resistor is touching the bowl and causing a short that only appears when you have the shell touching the fame, which is grounded.

MichaelB brings up a good point.  If the smoke element is touching the bowl it will be a ground when the shell is installed.  If the shell is removed then ground/short is removed.   This can develop easily after smoke wadding replacement or resistor replacement. 

Measure pink wire/pin to shell and then red wire/pin to shell.  Any low resistance continuity there is your problem.  Remove the smoke unit board and bend your element away from bowl.  Put smoke unit board back on then measure the resistor screws to bowl and confirm open (not touching) before you install everything back together.   

BINGO! I opened up the smoke unit and it looked like the element was bent enough that it was touching the side of the bowl. I readjusted it so it was centered in the bowl and reattached everything, mounted it back up, and put the shell on with the screws. I turned it on and no breaker trips and ran it back and forth for a bit to test.

Thank you everyone for the help and @MichaelB and @Steims for the idea on checking the element.

BNSF-Matt posted:

BINGO! I opened up the smoke unit and it looked like the element was bent enough that it was touching the side of the bowl. I readjusted it so it was centered in the bowl and reattached everything, mounted it back up, and put the shell on with the screws. I turned it on and no breaker trips and ran it back and forth for a bit to test.

Thank you everyone for the help and @MichaelB and @Steims for the idea on checking the element.

Glad to see it was fixed without having to send it to a LHS. Hopefully no other problems will come up!