From: John Allain <allain(a)panix.com> at least HV SMPS! THose have enough high volts on the high side caps that discharge first is the rule. Water does not cause rust for the most part, oxygen does! However if the water has any impurities or even soaps in it there is a risk of electrolisys (so, wash and dry quickly). then I put them in the dishwasher on the power saving setting (no reheater). I've done boards like MVII cpu, Qbus RAM, PDP-8f front pannel and most of the boards (not the core board, loose cores would be ripped off) I deemed too dircty for dusting. Success is assured as commercial cleaners for electronics assembly do that. Over the years (20+) Ive done this and it's a great way to degrunge the nastiest (esp cigarett smoke). It's a most do for any electronics that has had salt exposure (Salt eats metals!) as it tend to remain even after dried does become hydroscopic leading to long term problems. Key things: Not too hot. How hot it too hot? 200f (100c) or cooler is safe. most Semiconductors (transistors, diodes, ICs) will safely stand 150c (at the junction) so that is the way to hot point. once cleaned rinse well if any soaps were used. Isopropanal can be used to dry (dewater) but it must be 95% or better. Rubbing Alchohol is usually either 70% or 91% with the rest being... water! Dry as soon as possible and throughly. A 190F (87) oven works well or blow dry. If there are any moving parts, lubricate as required with the correct oil (or grease). Paper, temperature sensitive plastics and any suspect items like closed but not sealed items (relays, some switches) may need closer attention to insure they dont get wet. Oh yes, a note on dry brushes or vacuums... remember you may be generating static and even TTL can suffer long term damage from low level ESD. Allison