So, got the adapter today. I have to say build-wise it actually looks quite decent, sturdy construction and okayish finish. Definitely made in China, not in Japan, but good enough. Also, there's a connector that sorta fits...not quite, but good enough to make it turn on. That's about the end of the good news though, still wavy interference-like noise...
Some tests I did:
- fiddling/fudging with the tray (softly pushing it, or softly pulling it) does nothing at all to the noise pattern. I think this would eliminate anything caused by mechanical play, because then you would be able to see it
- moving the scanner: no effect
- reversing the AC plug also doesn't do anything ... little chance that this had effect, but easy to try
- i've been scanning a bit of fully exposed trailer of positive film, and there's also a sticker on this part. There's also noise in the sticker, which is opaque, so it's not related to anything in the film itself, must be in the analog part of the circuit before the conversion to digital (or bits are being flipped, but that would look differently i think?)
I'll open the thing up and start fiddling with cables at random. Also cheap to try, can't hurt you'd think, right? ;)