Electrostatic forces like lightning don't behave like regular AC/DC
electricity. Around a massive discharge you get high field strengths
that can induce potentials in objects not even connected. This is the
EMP (electro-magnetic pulse). Sounds like the strike was close to you
and you should be glad you only lost a PSU.
In modern electronics it's small capacitive gaps that get damaged.
Electrolytic capacitors and CMOS gates get their insulation punched
through, which destroys the component. As plastic housings have
replaced metal ones there's little or no field shielding on gear these
days.
As others have said, for prevention your supply circuits should be
earthed. They should be anyway, for human health and safety reasons,
including an earth rod (long copper pipe or pole driven down into soil
at least 1 meter) so your earth return is not too far away. Usually
you also want an earth leakage sensor set to cut the supply if any
current is flowing through the earth circuit - very useful in a
damp/rainy environment.
Problem is; most switched mode PSUs use only the active pair (live and
neutral in single phase European terminology) so there's nowhere for
errant currents to go. Often they have an arrestor, as old copper
telephone systems did, and the idea is that it arcs across, closes the
arrestor and shorts the path (often blowing a fuse). With nearby
lightning you get >100kV very fast, and it all happens too quick.
In modern electronics it's small capacitive gaps that get damaged. Electrolytic capacitors and CMOS gates get their insulation punched through, which destroys the component. As plastic housings have replaced metal ones there's little or no field shielding on gear these days.
As others have said, for prevention your supply circuits should be earthed. They should be anyway, for human health and safety reasons, including an earth rod (long copper pipe or pole driven down into soil at least 1 meter) so your earth return is not too far away. Usually you also want an earth leakage sensor set to cut the supply if any current is flowing through the earth circuit - very useful in a damp/rainy environment.
Problem is; most switched mode PSUs use only the active pair (live and neutral in single phase European terminology) so there's nowhere for errant currents to go. Often they have an arrestor, as old copper telephone systems did, and the idea is that it arcs across, closes the arrestor and shorts the path (often blowing a fuse). With nearby lightning you get >100kV very fast, and it all happens too quick.