When looking at the exploded view diagrams, I see a component called "E. CAP" under the water tank.
My non-sound Porters don't seem to have a keep alive pre-installed, is this a feature I'd gain if I upgraded to a sound model?
If you have a look at the top diagram on the right it looks like your right.
Ton
The caps on the sound equipped Porters, are for sound only. They are not for motor keep alive.
Reg Barron
We are talking about this diagram.
http://www.bachmanntrains.com/home-usa/dwg/dwgs/On30%200-4-2%20Porter_Both%20DCC-%20and%20DCC%20Sound-Equpped.pdf
Ton
Well that's still good news to me.
Perhaps the capacitor's wires could be connected to the component that converts DCC to DC like this Heisler board?
http://www.dccguy.com/?p=5078
By the looks of the diagram it is already connected.
That sad i can't recollect ever seeing a capacitor when i transplanted the sound decoder to a 2-4-0.
But that is a few years ago.
Ton
If you want sound and motor keep alive in a Sound Porter, attach the blue wire on the same component as shown on the Heisler. The black and white stripped wire of the cap can go on the existing negative cap terminal of the sound board. I have used a TCS KA-2 in the past. Today I would use their KA-3, since it is smaller. I believe (in a previous topic) I provided a link to my thread on the Railroad Line Forums describing how to add keep alive to a few On30 locos.
Reg Barron
An aside ----
Caution: After adding capacitors for motor keep alive to decoders not designed for it you may encounter programming and false short-circuit glitches.