I've been cleaning circuit boards with 99% IPA for a decade, but a client's old radio made me question it.
A guy brought in a 1970s tube radio with a dusty, waxy board. I did my usual spray and scrub with 99% isopropyl alcohol, but it left this awful white haze. Turns out, the old wax coating on some components can dissolve and redeposit with pure IPA. A tech in a Milwaukee shop told me a 70/30 mix of IPA and distilled water can work better on vintage stuff to avoid that residue. I'm torn now between the absolute dryness of 99% and the gentler clean of a diluted mix. For those of you who handle a lot of older electronics, what's your go-to cleaner for these sensitive boards?