Did some flood recovery work in the 80's,similar cleaning
procedures but we also used a lo-temp bake oven to dry boards and
transformers,even motors were salvaged and re-bearinged. A megger
was the most important tool!
Eric Lemmon wrote:
> Around 1973, Hurricane Celeste struck Johnston Island- where the Air
> Force had an active THOR launch complex. The winds damaged the roof of
> the missile guidance station, allowing the Univac computer system to be
> heavily contaminated with salt water. I was in the first wave of
> technicians to return to the island, just 24 hours after the hurricane
> passed. Our first priority was to tear apart the entire electronic
> system and decontaminate every PC board, chassis, and the attaching
> hardware.
>
> Our resident chemist devised an extremely effective cleaning process.
> He filled 45-gallon GI cans with 1) dilute phosphoric acid, 2) deionized
> water, and 3) an azeotropic mixture of Freon TF
> (trichlorotrifluoroethane) and isopropyl alcohol. We had a "production
> line" which soused some very expensive ($2k to $15k) PC boards for ten
> seconds in each bath in the above sequence, followed by blowing off the
> excess with an air nozzle, then drying the board with a hair dryer. We
> were able to salvage 95% of the system this way, although it took
> several weeks to reassemble the station.
>
> Computer boards of this vintage were intended from the git-go to be
> housed in a sanitary, dust-free, benign environment that had controlled
> temperature and humidity. As you can imagine, getting showered with
> salt water has a high potential for total destruction of this
> equipment. It was through the chemist's "magic brew" that a vital
> rocket launch site was returned to ready status in an incredibly short
> time. Dunno if this process has been used in recent times.
>
> 73, Eric Lemmon WB6FLY
>
> ------------------------------------------------------------------------
> I agree... When I was a board tech, we would wash boards in a tub
> of organic cleaner. I can't remember the name of it, but we nicknamed it
> green death because it was pretty hard on our skin. After letting the
> board soak in it a while, we'd then take it out rinse it well, then dry
> it with compressed air. Never cleaned monitor boards though, I was
> nervous about getting water in or under the flyback.
>
> Richard, N7TGB
>
>
>
>
> I'd like to second Skipps comments and add one of my own. At the
> factory we used ordinary dish washers (until we got the commercial
> washers) to clean PC boards. Most components are water safe.
> Exceptions, are non hermetic parts like switches and transformers;
> things with paper or bakalite coil forms. Spic and Span is a little
> harsh. For general cleaning, including automatic dish washers,
> useArm and Hammer baking soda.
>
> If you think someone has used an acid flux (sometimes necessary to
> solder nickel or steel) clean with ammonia before the baking soda.
> Finally if you have rosin flux isopropyl alcohol works well. Don't
> use rubbing alcohol (contains water) or use alcohol in the automatic
> dish washer (it will burn).
>
> Fred AE6QL
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