OK, things are staring crystallize - First loco to get its conversion will be a "late model" Bachmann Climax. The set up will be a rechargeable battery pack, 12 x 1,2 v AA NiMH, arranged 3 + 3 + 6. Located as noted in the previous post. Looking at the documentation that comes with the loco it seems I can retain the standard DC PCB. So I will have the Sierra Card, RCS SSI-9, ESC and RX to go in the bunker, or thereabouts. All will be suitably insulated from each other than any necessary connection between them. The ESC will input into one of the pair of Battery terminals on the Bachmann PCB, as the manual seems to instruct and the speaker leads, factory fitted ready plugged into a socket on the PCB, will be re-installed as indicated on the Sierra card. The SSI-9 will take care of the "stay alive" on the Sierra as well as sort out the PWM voltage being fed to it by the ESC and will be installed as per its manual. I may dispense with the Sierra's remote volume control on this one loco as the Sierra card will be readily accessible by lifting off the dummy oil bunker. Before everybody screams, "disconnect the pickups !", I have been informed by someone in the US who does installs like this professionally that this version of the Climax has a reliable track pick up isolator. The chuff will be triggered by reed switch/magnet as shown of George Schreyers pages. Apart from any conjecture on the pick up scenario am I right so far ?
I am thinking, like the Accucraft K-27 conversion I did, that inputting the variable voltage through the battery input terminals on the std DC PC that all the directional lighting/flicker functions and smoke unit will behave as they would have done if receiving a variable voltage via the track pick ups. Can it be that simple ? On the K-27 the ESC input side had a 2nd set of fly leads that onward fed the battery voltage to a voltage regulator that fed the keep alive functions on that loco's Sierra, Again a 2nd set of leads were provided on the ESC's output side, one feeding direct into the loco's motor, via the K-27's simple terminal buss, and lighting circuits the other to a PWM - DC converter that fed the Sierra's voltage controlled functions. I appreciate that the SSI-9 may change exactly how the wiring is arranged but that's the gist of it. Max