On Fri, 10 Aug 2012 12:20:30 +0100, eastender wrote:
Talking of kitchen appliances, I tried cleaning a keyboard that had
not-working keys by giving it a good going over in the dishwasher. I got
a spakling clean keyboard but it still didn't work.

Usually[1] down to impurities/residue in the water/cleaning solution.
Splitting things down into component parts, cleaning, then rinsing with
distilled water and drying immediately helps a lot.

Beware of liquid getting trapped under ICs, too. Blowing accumulated
moisture from PCBs with compressed air or bunging in the airing cupboard
for a few days is usually a good plan.

[1] although modern keyboards usually use a flexible plastic membrane for
the key switch matrix; it's not impossible for one of the tracks on the
membrane to break (people who owned Sinclair Spectrums back in the day
may remember that fault, too!), which will also yield various (and
perhaps bizarre) combinations of non-working keys.

cheers

Jules