|
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
-----Original Message-----
From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED]On Behalf Of Fred Townsend Sent: Tuesday, January 03, 2006 11:18 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: interface to shut off a radio on temporaly base 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. YAHOO! GROUPS LINKS
|
- [Repeater-Builder] Cleaning PC Boards (was: Unrelated topic) Eric Lemmon
