[sdiy] Modular Video?

[Fahl, Romeo]

When I was going to school, one of my assignments was to calibrate a beat up
old O-Scope.  It was really hard holding two meter probes to the test points
with one hand and doing the calibration with the other, so I tried using
alligator clips....

zzzapppp!!!  woke up on the floor.  High voltages are no joking matter.

R.
 


-----Original Message-----
From: Jim Patchell [mailto:patchell at silcom.com]
Sent: Thursday, September 13, 2001 7:01 AM
To: John L Marshall
Cc: synth-diy at dropmix.xs4all.nl
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.