First post, by Jotschi
I found an old IBM mainboard on a flea market tour. It was initially very dirty so I gave it a quick bath with some soap and warm water. I rinsed it off with IPA to displace the water. After drying it became very "milky". When I use q-tips with IPA on those areas the tip becomes very dirty.
I think it is dirt on the PCB. There is also a place where the speaker (SP1) got ripped off. At that area the PCB is clean. That leads me to the conclusion that the IPA did not harm the board. Otherwise the area should also be affected.
Has anyone encountered this before? Any suggestions on how to clean it?
The photo show the issue with some areas already being dry and milky.