Rob wrote:

Recently my tower was hit by lightning. All my ham gear survived except
one. Since I forgot to unplug my Amp Supply LK-500ZB Linear Amp from the AC
power mains, the lightning found a nice way in.. (The rest of my ham gear
was disconnected from the power mains and the antenna)

I wasn't sure whether that amp was affected. But when I turned it on the
plate voltage was about half the normal value and the tubes were half as
bright.

What is the best way to troubleshoot and repair an amp that was damaged by
lightning NOT through the antenna BUT through the AC power mains?

What components will likely need to be replaced? Just the caps? What about
the transformer?

Is it worth repairing in the first place?

73's
Rob

Transformer, diodes, caps are all subject to damage.

I once had a transformer damaged by a nearby strike. I decided to
repair it since it was a multi winding jog that would have been hard
to replace. I unwound and counted turns, measuring the wire size for
each winding. This was an old style transformer with each layer,
neatly flat wound on a fresh layer of paper. Everything looked fine
till I got to the very first turn on the bottom winding.

It had been started sloppily, diagonally, and where it passed under
other turns, the insulation was burned through. This few turn short
lowered the output voltage of all the windings and after a few
seconds, blew the primary fuse.

--
John Popelish