dcc in brass

[ARTHILL]

Still looking for someone who actually put DCC in an old brass engine and made it work. I have a Sierra and a three truck Shay that I want to start with. Having never tried putting DCC in anything I need some detailed advice. The last time I built a railroad, they hadn't even thaought of DCC.

Thanks

[rrinker]

I will have a couple to do for my father-in-law, but he's havingme convert some of his newer stuff first.

A few things to consider - the current drawof the motor. Most newer brass has decent motors, and won't be a problem. Some of those older models - you need tot est with an ammeter to see how much current the motor draws when stalled at 12V. If it's about 1.5 amps or less, you're good to go, most HO and even some smaller can handle 1.5-2.0 amps stall current.
Next thing - motor isolation. Neither brush can be connected to the frame in any way - a lot of motors have one brush connected to the motor case and thus to the frame via the motor mounting screw(s). This connection will instantly fry a DCC decoder. Isolating it depends on how themotor is made, it's goign to be different for every type of motor. Some you can isolate the brush lead that connects to the motor frame. Others you will have to figure out a way to insulate the motor from the loco frame. If the motor has two wires coming out of it, it's PROBABLY isolated - check with the continuity setting on a meter. There should be an open circuit between either motor lead and the frame, and either motor lead and the motor frame.
If 1 and 2 are met, installing the decoder is as easy as connecting the red and black wires to the track pickups and grey and orange to the motor leads. The only way to really solve 1 is to replace the motor with a newer one.

--Randy

[Sperandeo]

Randy has really covered it – there's less to a basic installation than you might think – but I'll add that it's a good idea to replace an old open-frame motor with a newer enclosed "can" motor while you have the locomotive apart. This will generally improve the performance of the old model, reduce the current drain to be more compatible with decoder capacities, and solve the problem of isolating motor brushes all at the same time. Can motors have both brushes mounted in a plastic end cap, and neither one is grounded to the motor case – they're already isolated.

Good luck,

Andy

[Anonymous]

Most (not all) earlier brass with open frame motors had a very simple drive train with a worm gear soldered directly to the OFM motor shaft, directly driving a nylon or delron plastic gear mounted on a driver axle. The only practical way to re-motor these is to also re-gear them - quite doable but not for the faint of heart and requiring investment in a gear puller and a quarterer. Having given that caution, in my experience re-motoring is usually the only practical way to convert an old-style OFM brass model to DCC.