Now that you mention it, my earliest keyboards did seem to last forever. One only died when I spilled some grapejuice in it....LOL....
I was fortunate that some years back my company did a clean out of extra/old inventory. There was such a pile of it, that they let us go and take some of it with the stipulation that we take it home and not leave any of it at our desks, defeating their purpose of cleaning out. Among a few other things, I took several good keyboards, so have had extras as the cheaper ones died young deaths....heh...
I don't think I realized there was an adaptor. I just didn't think of it to go look.