This doesn't really count as a complex sound conversion, as this is basically just a drop-in LokSound Nano NEXT18 install, but I thought it might be useful to document and share.
The latest runs of the Broadway Limited Imports' SW7 and NW2 switchers are available in a Stealth version that has a standard NEXT18 connector on the main circuit board. This makes an ESU LokSound install very straightforward — all you need is the LokSound Nano NEXT 18 decoder (58928). This avoids the need to pay for BLI's terrible Paragon 4 sound decoders, which I'm not a fan of for a variety of reasons (primarily lack of reliability).
Removing the shell requires removing two screws on the underside either side of the front truck, and one screw under the cab. You also need to carefully pry out the ends of the cab handrails that terminate on the frame sides next to the cab step wells. These are metal, and so fairly strong and can be rotated out of the way of the chassis. You can then lift the die cast hood and plastic cab away from the chassis.
There is a small daughterboard PCB in the cab roof that can be carefully unclipped using a flat head screwdriver.
The chassis is very well designed and has a coreless motor, flywheel/worms, and wired connections to the trucks with JST connectors. The main board PCB is documented by BLI and they are to be commended for this and the fact that the GND and U+ pins on the NEXT18 connector are terminated.
There is plenty of space under the long hood for a TCS KA-N1 Keep alive. There is a GND pad available on the underside of the light board (labelled L3-). This terminates the black wire on the TCS KA-N1…
There is a convenient U+ connection on the cab light J1 daughterboard (red wire pad), and this terminates the blue wire on the TCS KA-N1…
I took the S0560 Project from ESU and loaded this via my LokProgrammer. The coreless motor requires some tuning of the BEMF settings as follows:
Regulation Reference Voltage [CV53] = 120
K [CV54] = 15
I [CV55] = 120
K slow [CV52] = 6
K slow cutoff [CV51] = 30
K influence at slow speed [CV56] = 255
Slow speed BEMF sampling period [CV116] = 30
Full speed BEMF sampling period [CV117] = 50
Slow speed BEMF measuring gap [CV118] = 40
Full speed BEMF measuring gap[CV1169 = 40
I set the full speed [CV5] to 46 to limit the maximum speed to 30 mph
With these settings the loco performs extremely well with perfect slow speed control and has a very quiet drive train.
Unlike the Kato NW2, BLI have used a die cast metal shell which greatly enhances pulling power. On flat track, this diminutive SW7 can pull 24 heavy sixty foot boxcars with ease. It can also walk 8 sixty foot boxcars up my 2.3% grades.
As a digression, I have wasted a significant number of hours attempting to fix Kato NW2s for my fellow N scalers. Even without DCC or sound, these have very limited pulling power, and suffer from a design issue with a slipping gear on metal shaft that cannot be fixed (replacement parts fail in exactly the same way after any significant use).
So for me, this BLI SW7 is a game changer. I can finally realistically switch decent cuts of cars, and enjoy ESU's excellent motor control, and have sound with a keep alive.
I chopped the master sound volume down to 20%, and the prime mover slot to 40% within that. This yields lovely quiet undistorted burble of EMD 567 goodness. I think most people have an unrealistic idea of how loud sound-equipped locos need to be. I find a more scale sized sound that blends into the overall layout to work best. With my ProtoThrottle and a ton of momentum, pottering up and down some industrial trackage becomes very satisfying and brings a smile to my face.
I would thoroughly recommend these locos when equipped with an ESU Nano decoder. It is amazing what is possible in N scale these days.
Cheers
