Thanks for your comments. The receiver is an onboard receiver (Crest) but it isn't onboard. It is in a plastic project box next to my battery (24 volt wheelchair battery). I control it with a Crest Revolution TE transmitter. It is about 4 years old.
I don't know the age of the sound tender or how to test it off-track. There could be other problems other than the power supply - the locomotive, the tether, the LGB sound board (though the tender was described as new).
UPDATE: I figured it out - at least on my test track. First all the 20230 was not designed for sound, so the switch on the boiler was set to the wrong number. That should have been obvious, but the obvious often escapes me. Second, and more important, the tether I used was already on the locomotive. The 69232, however, uses a special tether in which the wiring for four of the five wires are relocated in the pin (see top connector in photo). Of course as you can see this tether was labeled 69232. As I said earlier about the obvious. I should note that the tether only works when installed with the re-wired connector on the tender side.
I am not sure if the 20230 has a chuff sensor or if this work on my Aristocraft mediated outdoor track.