At ECLSTS in April 2002, I purchased an SD45 smoke unit with the idea of installing it in my U-boat. I bought the U25B in June 2001 on a closeout, from TrainWorld for $109. It has the newer trucks and extra weight and that's it. On it's first running, it smoked like it was on fire. (It was a good thing) The second time out it failed. Aristo sent me a total of 5 replacement units and one complete blower fan, (thanks Mike H.) but they all failed shortly after they were installed. Well, I jumped at the chance to install this new smoke unit. It was really pretty simple. Here goes:
Remove the current stack (2 screws). Unplug it, flip it over and remove the 4 screws, and then take it apart and keep the top (the SD45 smoke unit sort of fits into it)...discard the bottom half. Now take the U25B flip IT over.
Remove the 2 screws in the front of each truck. Remove fuel tank, 4 screws. Remove the screw that's under the tank. Flip it back over. Carefully remove (rock & pull) the 2 horns. Using a small screw driver remove the square plate where the horns were. It's attached with 2 sided tape, Once removed, remove the little screw. Now the long part of the U25B lifts off.
Remove the blower fan and tube that attached to the top of the hood. I cut the 2 leads that attach to the on/off switch to a length that would be good to attach the plugged wires that come with the SD45 smoke unit. I used small shrink tubing and solder for this.... NOW for the hard part (sort of).
Using a rotor-tool cut off the stack almost flush to the top...this is so the new units opening will be centered. The U25B's opening is off to one side. Once you've done that try the new unit and make any adjustments. Now mark on the top unit where the NEW unit hangs off a little (plug side). Cut the piece out with the rotor-tool. When the new unit fits in good use some CA in the front and the back and let dry a few seconds. Insert the completed NEW unit in the opening and reattach it with the 2 screws. Attach the plug, set your switch to smoke and motor off.
Place on a test track. Puts in 3-4 drops of smoke fluid and turn on the power...If all is good re-assemble.
On the top long hood side of the U25B you'll see 3 small square plates. I drilled a 3/32" hole in the center of each plate on both sides. The fan LIKES to draw air and there are NO openings (like real screens) on this U25B. My unit ran at 1:1 scale speed for over an hour with 30-40 drops .I know this change seems complicated but, it wasn’t. It took me about 90 minutes to do.
WHAT AN IMPROVEMENT!