A good soak (an hour has usually been plenty) in a hot water solution of Oxi-clean (I use Biz) and powdered laundry detergent (I use Charlie's) has almost never failed to clean keys for me, without any additional work such as scrubbing.
What is with the "active" vs "passive" adapters, and all the warnings? I have at least half a dozen of the cheapest adapters around, DIN-to-PS2, PS2-to-USB, and have used them with many brands of vintage keyboards including IBM (including Model F XT and AT), Chicony, Compaq, Dell, NMB, BTC, and lots of others.
They have never failed to function properly, even on laptops, under Windows and Linux, except when the laptop was on battery power and then I don't think it would have mattered anyway.
Have I just been supremely lucky? Or does my habit of building larger power supplies into my cabinets, and keeping cable lengths as short as possible, help me out here?
Keeping everything plugged in nice and tight seems to offer a bigger problem. Why are PS2 connectors on motherboards so lame?