I was cleaning every board with isopropyl alcohol for years before a job in Seattle showed me why that's bad

I was fixing a vintage Pioneer receiver for a client up there and kept getting weird resistance readings after my usual 99% IPA scrub. An old timer at a local parts shop told me the alcohol was leaving a film on some older flux types, messing with my meter. He said for boards from that era, a specific non-residue cleaner like MG Chemicals 4140 works better. Has anyone else run into this with gear from the 70s or 80s?

3 comments

3 Comments

grace_fox32mo ago

Had the same issue with an old Sansui amp. Switched to a 50/50 mix of distilled water and vinegar for the initial clean, then rinsed with deionized water. Dried it completely with a heat gun on low. The meter readings went back to normal after that.

colemartinez2mo ago

Honestly always thought you had to use fancy contact cleaner for that kind of thing. Reading what @grace_fox3 did with the vinegar mix is a game changer. I had a similar problem with an old receiver and just kept spraying expensive stuff that didn't really work. That method of cleaning with something simple then rinsing well makes total sense. It probably gets at the gunk without leaving any residue behind. Might have to dig that old unit out of the garage and try it.

hill.hugo1mo ago

Funny enough I tried something similar once and accidentally melted a plastic connector with the heat gun. Guess that's what I get for thinking I could cook an amp back to life. At least the vinegar trick worked better on the next unit I tried it on.