A number of us have been working on these ATLAS conversions to sound. I got an Email from BandmnJim and do not know how to reply or determine if he got my reply. The answer to his question is one that many will find interesting so I hope he reads this posts and understands.
He asked if I had any experience with “early” ATLAS RS 3 and sound and how they are different. My only RS 3 experience is putting sound in my “new” RS 3 s and now my 'old" RS 1.
Their is plenty of room in the RS 1 but you need to work out a different arrangement for the light “transmitters”, the long plastic lenses that move light to the headlight locations. Now the RS 1 is not an RS 3. Having no sound decoder for RS 1 I am happy to use the RS 3. The same loping diesel prime mover was associated with them as well. They all sounded like they would stall with each rev of the engine. The Tony’s mini oval with “speakeasy baffle” gives plenty of sound. My “old” RS 1 is one of my best performers.
Jim’s question was retrofiting the “early” Kato Roco RS 3’s. The way the power is conducted from the light board to the brushes is via two brass straps about 1/8 inch wide. On “new” versions these are held in place with a plastic clip. ATLAS has already soldered wires to these and they make the conversion simple.On the “early” versions these plastic clips do not exist and when you dis engage them from the light board they are somewhat spring loaded and stick out towards the outside. The quickest remedy here is to solder lead wires on them to go to the Soundtrax and just tape them to the side of the motor. Another way is to solder new loops to the Soundtrax decoder and pass the brass straps through these loops. The holes are in the circuit board and solder “lands” are there also. Solder on the side with fewest components. The holes are arranged exactly like other drop in decoders for these locomotives. Directly