[sdiy] Modular Video?

[John L Marshall]

The cage was to contain the RF. The high voltage is derived from the
horizontal oscillator. The horizontal oscillator is a saw tooth running at
15,750 Hz, lots of harmonics and lots of energy. On your old set the flyback
transformer also had a winding to power the filament of the rectifier tube
(valve). The horizontal oscillator is the second biggest valve (tube) in the
TV.

If your hearing is good you can easily hear the horizontal oscillator. It
sometimes helps to turn your head. Keep turning... you will hear it.

----- Original Message -----
From: Jim Patchell <patchell at silcom.com>
To: John L Marshall <john.l.marshall at gte.net>
Cc: <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, September 13, 2001 7:01 AM
Subject: Re: [sdiy] Modular Video?


>     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.
>