As I promised, here is a sort of tutorial on how to convert the Bachmann Berkshire to an ESU Loksound with a much better speaker.
First, my "list of supplies" include an ESU LokSound Select Micro with the Loksound Heavy Steam collection file installed (it's file #73814). The speaker I used is a Knowles Dumbo 13 x 18mm, which has now been replaced by the Knowles Grand (same size, a bit thinner). These speakers are available from Digikey. The speaker was set in a custom enclosure made from .040 styrene on the sides and 1/32 lead sheet for the bottom (to add weight). To make the enclosure the right volume, the long sides of the enclosure are 6.3 mm high (I used .040 x .250 styrene strip for the sides) and 25mm long - that is, the enclosure extends 7mm beyond the speaker length. To seal this, I used a small piece of 1/32 lead sheet on top. You can see how the speaker enclosure looks in the following photo:
The little piece of lead on the right is there simply to make the top of the right side of the enclosure the same height as the left side.
I also used a TCS six-wire micro connector harness to do the wiring:
OK. Now let's start.
The first thing I do is strip out the circuit board and decoder board. You'll need to remove the tender shell by taking out the four screws (one at each corner) on the underside of the tender, and then lifting the shell. Then unplug the wiring harness from the engine, and slip it out of the end of the shell. Set the shell aside for now. The decoder board simply pulls up and away from the base circuit board, and you will then see two small philips screws at each end. Remove these and the circuit board comes out. Clip off the wires going to the round speaker in the bottom of the tender. Below the circuit board is a plastic "sub-base" insulator, which you want to keep. It will have some "nubs" on either end, which I cut off and sand down. Here is a photo of the "stripped" tender floor with the nubs sanded off at each end:
Next, I hard-wire the tender truck pickups. To do this, use some flexible 30-gauge wire soldered to the pickup "tabs" that stickup from the trucks into the tender. Here's how to do that. First, unscrew the two screws that hold the plastic insulator sub base on the tender frame. Remove it and set it aside (and also remove the round speaker sitting in the tender floor). Now lightly sand the inside of each of the pickup tabs to roughen the surface. Tin the very tip of the inside of each of the tender wiper arms. Now take two lengths of red and black wire that are long enough to stretch from the front tender truck tab to the rear one, plus some extra to allow for the trucks to swivel. Strip about 1mm of insulation from one end of each wire, tin it, and then solder them to the tabs of the front tender truck. Now slip those wires through the plastic insulator sub base, and put it back on the tender floor. Strip about 3mm (1/8") of insulation from the other end of the wires. Cut two additional lengths of wire that are about half as long as the wires you just soldered, strip 3mm of insulation from one end of these wires, and then twist the ends together with the stripped ends of the matching wire and tin the twisted end. Now solder these to the matching tab on the rear truck. YOU WILL NEED TO BE CAREFUL: REMEMBER THAT THE PLASTIC SUB FLOOR IS PLASTIC AND WILL MELT.
Here's a photo of the completed hard-wire:
Now set the tender floor aside. Next, we're going to attach the color-coded micro plug to the engine wiring harness. The wiring harness has a mini plug on it, but all the wires are black. I replace this with a color-coded micro plug because (1) the plug assembly is smaller and takes up less room and (2) the color coding will cut down on wiring mistakes. But to attach the color-coded plug to the engine harness, you have to identify each wire correctly. Fortunately, Bachmann has made this easy, by listing the pin outs on the base circuit board. Here's a photo of that, and you can see the symbols for the pin outs on the left of the connector (the top most pin is right power, or the red wire; the next pin is M+ - motor power, or the orange wire; next is L+ - the blue wire; next is L-, which is the white wire; then M-, the gray wire, and finally L power, the black wire):
Now what I do is cut each of the black wires off its plug and solder them to the corresponding wire on the color-coded micro plug. I cut the wires on the plug to about 1.5" and then cut each of the corresponding black wires from the engine back about 1.5" so that the overall length of the harness is about the same as it was. DO THIS ONE WIRE AT A TIME, or else you will lose track of which wire is which (ask me how I know this). Here is a photo of the completed engine wiring harness (the blue wire fell off the micro plug as I was doing this, so I had to resolder it to the plug; I used a piece of clear heat-shrink tubing to insulate it, which is why it looks different than the other wires). Don't forget to insulate your wire joints with heat-shrink tubing.
OK. Now it's time to work on the tender shell. I install the speaker under the coal load, so the first thing I do is drill a bunch of #70 holes in the coal load. Here's a photo:
Then I insert the speaker; I use a dab of thick CA at each corner on the top of the enclosure to glue it to the underside of the coal load, and then I also use styrene strip to "pack" the sides agains the tender shell; this latter step helps make sure the shell won't vibrate and cause sound distortion when the speaker is going full blast. Here's a photo of the installed speaker:
I also install a 3mm sunny white LED to light the backup light. To save space, I "flatten" the LED by sanding down the sides - you can take at least a half-mm off each side this way. Then I trim the plastic that sticks out from that back to where the posts are for the tender screws, and then glue the LED to the top of the tender shell butting up against the trimmed light pipe. Here's a photo of the completed shell with the LED installed. Note that I have already put a dropping resistor on the negative lead of the LED (where the yellow wire is attached) and insulated that with heat-shrink tubing. I use a 1K, 1/8w resistor for this (I also put some kapton tape over the lead sheet that is the bottom of the speaker enclosure, just as insurance against any stray electrical shorts).
Now it's time to mount the ESU LokSound on the tender floor. I just glue it in place with a dab of thick CA on the rear of the decoder. Here's a photo:
Now it's time to wire the ESU to the color-coded harness (the male side; I used the female side for the engine harness). I cut the wires on the male plug to about 1.25" long, then strip 1mm of insulation from each wire and tin them. Then it is time to start wiring the male plug to the decoder. Again, I do this one wire at a time, starting with the red. The red and black wires are a bit more complicated, because you will want to wire the ESU's pickup wire to the tender truck pickups at the same time. This is why we have that extra wire from the tender trucks. First, cut the red and black wires to about the same length as the "extra" wire from the tender trucks. Then strip 3mm of insulation from all the wires; twist the reds together and the blacks together, and then tin them with solder. Trim the soldered ends of the wires to about 2mm. Cut a 4mm piece of heat shrink tubing, slip it over the red wire on the male plug harness, then solder the red harness wire to the combined red wires from the ESU and the tender pickup, and then slip your tubing over the joint to insulate it. Here is a photo of the completed red and black wires ready to be soldered to the male plug harness:
Now it's just a matter of wiring everything one wire at a time. When you get to the blue wire, cut a 1.5" piece of spare blue wire and wire it together with the ESU's blue wire, then wire that to the blue wire on the male plug. This "extra" blue wire will be used to connect up the rear LED. When you are done wiring everything (brown wires to the speaker, yellow wire to the rear LED), you can slip the engine harness female plug through the opening on the tender, and hook it up to the male plug you've just finished wiring. Here is a photo of all the wiring completed:
DON'T FORGET TO USE A DROPPING RESISTOR ON THE WHITE WIRE! The Bachmann LED that lights the front headlight DOES NOT have a dropping resistor already on it. You can either wire this resistor in the tender, or what I did was put it in the boiler - I removed the boiler shell, found the black wire that is the negative headlight LED wire, cut it, and wired in a 1K, 1/8-watt resistor in the "channel" between the frame halves (don't forget to insulate this with heat-shrink tubing). But you can put the resistor wherever you'd like.
Next step is simply to stuff all the wires into the shell behind the speaker, put the screws back in the bottom to hold the shell on, and reattach the tender to the engine (I'd suggest testing your installation before you put the shell back on, though!).
At the end, you will need to adjust the ESU LokSound's CVs to pick whatever whistle you want (I used #15; set CV 48 = 15 to do this) and you will also need to adjust the BEMF parameters to get best performance out of the Berk. The parameters that need adjusting are CV's 52, 53, 54, 55 and 56. Here are the values I used, though you'll likely need to tweak them yourself:
CV 52 = 10
CV 53 = 140
CV 54 = 120
CV 55 = 5
CV 56 = 255
And when you are done, you get this:
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John C.
