I think working around the voltage limitations of the electronics is what we're trying to do at this point. I'll take GGG's word for it on the limits of each of the boards in this case, as it seems reasonable to me. The R2LC and Railsounds boards cant go over 19VAC, but the motor driver DCDR looks good up to at least 35V. I have to assume this is an on board 35VDC, so the max AC would be what... 35 / 1.4141 or 24.7 volts AC on the input. That will be fine with the 22VAC output of a Z4K.
So, what we need to do is cut the voltage to the R2LC and Railsounds boards so that it cant exceed 19VAC even if track voltage is up to 22VAC. Unfortunately there is no such thing as a 'simple' AC voltage regulator, so I think the simplest solution here is to use pairs of diodes in series to lower the voltage. if we assume the input will never exceed 22VAC, the limit of the Z4000 transformer, then we need at least 3 volts of drop on through the diodes. That's 5 diodes at the typical .6volts each. I'm going to add an extra one in for a little wiggle room. So what we need is 12 diodes wired up in reversed pairs to allow AC to flow through them for a 3.6 volt drop. This string of diodes then has to be placed in line with the power to the R2LC board, which is pin #1 on the board.
I'm not sure what the best way is to do this. I've thought of unsoldering, or cutting off the pin then soldering wires to each side of the socket on pin1 and inserting the diodes there. Another option would be to build a short jumper cable between the boards with the pin1 wire extended to place the diodes in series. The jumper is probably a better option if you want to preserve the boards, but cutting off the pin is quick and easy. The same process will have to be repeated on the sound board if you have one, and I'll have to look up what pin the AC Hot connection is, or exactly how the railsounds board is hooked up. As said in an earlier post, I'm not super familiar with ERR electronics.
Two small issues I see with this method are that the "turn on" voltage to the engine will be higher, going from maybe 8 volts up to almost 12, but I doubt this will cause any problems for you. The second issue will be making sure any lightbulbs in the engine or cars are rated for the higher voltage.
A third issue worth mentioning is that you'll have to make sure you don't forget to turn the voltage down if you run another engine on that track.
JGL
