Fwd: Re: [sdiy] Modular Video?

[greg montalbano]

Yah, just shows how things have changed over the years --
the technique for discharging those HV tubes used to be common knowledge
among DIY techs (as I learned the hard way, many years ago...)


>Date: Thu, 13 Sep 2001 07:01:23 -0700
>From: Jim Patchell <patchell at silcom.com>
>
>     Speaking as one who has been zapped by a picture tube, it is not at all
>pleasant.  It is also very bizarre.  The only time this happened to me was
>when I was trying to change the high voltage rectifier in an old RCA (1961
>vintage) color TV my parents had.  The tube was inside of an shielded box, for
>X-RAYs I was told.  I got the old tube out ok, but I touched something when I
>put the new one in.  It was sort of like the experiment where you use a
>battery to make a frog leg twitch.  My hand flew out of the shielded box,
>scrapping knuckles on the way out, and slammed into the side of the TV with
>enough force to give me a bruise.  The electric shock did not actually hurt
>that much, but the reaction did, so, there are may ways to be hurt by the
>voltages stored in picture tube circuits (at least in new sets there are no
>high voltage rectifier tubes...opps, that might be politically incorrect in
>this group... ;^)   )
>
>     -Jim
>
>John L Marshall wrote:
>
> > Agreed.
> >
> > Lethal voltage 10KV to 60KV is stored in the CRT. The filter capacitor for
> > the anode power supply is the picture tube. Note the conductive coating on
> > the inside and outside of the glass dialectric, a near perfect capacitor.
> > The charge can be stored for days.
> > > >
> > >
> > > Bear in mind televisions generate lethal voltages, NEVER work on line
> > > operated equipment while it is plugged in.