High voltages (was a new BBS...)

Brian L. Stuart blstuart at bellsouth.net
Mon Sep 22 09:54:39 CDT 2008


>     Ok, let's be serious here: Most of the shock you take from CRTs is more 
> "oops" than electrical shock. A 26000 volts shock hurts, but not THAT bad. 
> There isn't enough power to make your heart stop. If the monitor is turned 
> on, the frequency is so high that the electrons travel on the top of your 
> skin. If the monitor is off, there is NO enough charge on the tube, and it 
> is discharged by a some megohms resitor to ground. Period. So it is not a 
> life concern, but only the scare.
> 
>     Don't be scare of CRTs, they bite but don't hurt :o)

Electricity and the human body are a weird combination with
often unexpected results.  Lo these many years ago back in
high school, I took my Yaesu HF rig to school to show the
class a little about ham radio.  After demoing things, I
powered it down and opened it up to show them what was inside.
Then I made the fateful move (well, not so fateful; I'm still
here to tell the story) to open the cage with the transmitter
final tubes.  Things had been powered down for a while,
about 20 minutes as I recall.  I reached in to see if the
tube was still hot and got close to the plate connection on
the top.  The tip of my finger was close to that and the side
of my finger just past the outermost knuckle was close to
the grounded cage.  The shock threw me back against the
wall behind me.  When I looked, there were a couple of
nice little "holes" in my finger.  The one on the side
looked as if something inside had blown outward.  Of course,
after the "what the....?" my first thought was, "guess
the caps in the plate circuit hadn't discharged yet."

>     PS: I'm not a medical doctor, I don't warrant you of nothing I said 
> here. If you put your tongue on the wrong flyback end and it hurts, I'm not 
> responsible. Void where prohibited. Your milegage may vary. Batteries not 
> incluided. If you die because anything I wrote here, the problem is 
> enteirely yours.

Ditto...

BLS




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