Just a bit on my philosophy about turning things off and on.
Ages ago I worked for a company that made computer peripherals. An
account I was dealing with had hundreds of Smart CRT terminals.
Any time a storm was in the area we would cringe because we knew if
the power went out some(a lot) of those terminals wouldn't come
back on line. We might have to zig zag across the state to repair
them. The failures were always attributed lightning or surges on
the power or data lines.
The customer then instituted a program to power down and disconnect
the terminals when they felt there was a good chance that a thunder
storm was nearby. Guess what? Same number of failures!
Customers also noticed that when the techs would come in to do
scheduled preventive maintenance there was good chance they were
going to 'break' the terminal. Often the only action was to power
it down, lift the top, do a visual inspection, and power it back up.
How many times have you heard "It was working fine when I turned it
off"? Have you ever noticed that light bulbs very rarely burn out
after they've been on a while? But, you walk into a dark room, flip
the switch on and all you get is a brief flash. (Kinda sounds like Andy
Rooney. Huh).
I always felt the main culprit was repeated expansion/contraction due
to the thermal change when powering up/down the device.
A few years ago while working in a wafer fab I asked the QC guy, whose
job was to determine failure modes of returned devices, what were the
biggest reasons for failures. Number one, overheating. Due either to
poor heat sinking, poor ventilation or excess current. Number two,
stresses. Due to manufacturing processes or thermal cycling.
So that's why I leave the things that I want least to fail- turned on.
That would be my HF rig and my work computer.
My philosophy about lightening protection: Yous pays yous money and
yous take yous chances.
On the air since 1971 this is my first damage from lightening.
$1.50 for the part from Digikey. If it happens again I reserve the
right to change my philosophy. :)
Mileage Does Vary,
k2ox
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