Hmmm. Turns out it wasn't so simple, since I misremembered the code. Instead, it has a fixed set of dependencies including the technology for unlocking the original machine (if it exists), Steel Processing and Electronics.
I assume it's some weird interaction where Electric Furnaces adds electronics to the QA technology without checking to see if it already has electronics.
Wait, the technology for unlocking the original machine IS electronics... Why would they do that???