Items used:
ESU 58420 LokSound decoder with NA class sound
DCCSound Premium sugarcube NA class speaker
DCCSound stay alive circuit (twin capacitors)
Haskell's On30 RTR model has room for a decoder in the smokebox, and a speaker in the coal bunker, while a twin capacitor stay alive resides in the boiler top.
To access the 8 pin plug, remove the small hatch cover on the underside of the loco, near the 2nd driver. Once removed, use a jeweller's screwdriver to remove the screw inside the hatch and once removed, the boiler's top is free to remove.
The 8 pin socket PCB is located in the smokebox and needs to be extracted in order to plug the decoder in. Once the PCB is extracted, plug the decoder in, being careful not to pull on the red and black pickup wires. If they break (which they can quite easily), the water tanks must be removed in order to resolder the wires to the phosphor bronze pickups. Broken pickup wires have been seen in about 80% of models that we have seen come in for a sound fit out.
Insert the stay alive capacitors into the two forward domes.
Next, solder the speaker to the small PCB in the bunker. The bunker is accessed by removing a false floor under where the coal would reside.
Ensure the PCB is wrapped in kapton tape to prevent a short with the speaker.
Next, solder the decoder's brown speaker wires to the PCB that the decoder plugs into, where the purple wires connect. These purple wires run from the PCB to the small PCB in the coal bunker.
Test run the model to ensure proper operation.
If the model performs as expected, it is time to refit the boiler top. When positioning and fixing the boiler top back in place, pay attention to keeping wires away from:
a) the drive mechanism
b) the join in the boiler
c) the boiler top stand which mates to the lower half and takes the fixing screw.
The wires are easily crushed so apply care.