Apple Lisa 1 - restoration project

John Honniball wrote: There's a lot of corrosion there you have to clean first before you ever turn this on. The KOH electrolyte which leaks out is akaline--and it's easier to clean at this stage. You can to brush it off with a white vinegar(acidic) to neutralize the pH balance, then brush it all off with isopropyl alcohol to remove any other residue and blow dry it. *But*, this has gone way past the leakage stage, the bluish-green corrosion indicates that it's already oxidizing--on the copper traces, components, and even solder. This makes it very tough to clean with just a tooth brush, as the corrosion actually creeps under the green mask., and under the chips where there's plenty of traces. And it becomes very hard to resolder anything. Usually the only method is to: 1. Desolder all the components in that area --remove every bit of corrosion with mini wire brush, 320grit sandpaper, and/or a dremel wire wheel). --if any corrosion remains, it will just grow again and spread. 2. Flux all the feedthrough holes -these will be very stubborn --you'll have to flux them several times to make the solder adhere properly to avoid further cold solder connections--and then desolder them again. 3. Inspect all the component leads for tension before soldering them back on --bend them a little-- as the corrosion creates microscopic cracks. --since you have the chips out, use IC sockets in there place. This may sound like hard work but it's the only recourse and it pays off. Don't expect the circuit board to look as pretty as before--you can always buy green mask refills--it's recommended. Your computer will be happy to work afterwards. =Dan -- [ Pittsburgh 250th --- http://www2.applegate.org/~ragooman/ ]