On Thu, 28 Jul 2011 10:04:30 +0100, "Gareth Magennis"
wrote:

As for the bulging caps, it would surely take some power to do this, which I
guess could not come from a PAT tester, though if they were zapped by one,
subsequent use of the unit with its own power supply may cause further
damage?

Just a minor note... It takes some time for bulging caps to develop.
It's unlikely that there's enough energy in a wall wart to destroy the
caps during a PAT test. It's also not over voltage that kills the
caps. It's the ripple current through the cap that causes the
heating. A cap, with a fixed DC voltage applied, will not blow
(unless the dielectric is perforated). More likely, the caps were
defective and blown for many months prior to the PAT test.


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Jeff Liebermann
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