Some conformal coatings, which protect PCBs from dust and moisture, can emit ethyl acetate or butyl acetate if they weren't fully cured. The smell is sweet but absolutely revolting.
replyWow this absolutely might be the answer!
replyEthyl acetate is used to wash flux off PCBs.
It's also used as an artificial flavoring in British "pear drops" which is probably why some people say it smells like pineapple.
Thanks for confirming I'm not insane!
replyIt is a sweet odor, but chemically irritating. It cannot be good to breathe.
I'm shocked no one has identified the source of the odor yet. Is it thermal paste? Flux/solder paste? Turtle jizz?