On Friday 06 May 2005 06:01 pm, Norm Stewart wrote:
> >>The other reason it's that thick is because of lead in the glass to absorb
> >>x-rays, at least for color tubes, which is what makes TV sets and
> >>monitors a bit "hazmat" rather than just being able to put 'em in the
> >>trash. Monochrome monitors and old B&W tv sets don't have that issue.
> >
> >Why is x-rays created, and why is it not beeing created in BW TVs?
> >Always wondered..
> >
> >Hell this is getting OT.. maybe we should take it to E_101.
> >
> >ST
>
> B/W tv's used 15Kv or so accelerating voltage - created soft x-rays.
Even that's a little high, 12KV was more common.
> Color sets needed more energetic electrons for the color phosphors, so
> used ~23Kv, IIRC,
25KV was more common, and in the earlier tube stuff the shunt-type regulator
tube would age, and the voltage would climb somewhat, except of course that
the tube-type HV rectifier was also aging. Then there was the occasional
fault, like the infamous "4-legged capacitor" that Zenith had a problem
with. It seems that the cap maker substituted materials or similar and these
failed rapidly, and drastically, allowing the HV to go up over 40KV.
Sometimes it was so bad it'd arc right through the glass and crack the tube.
All of those failures were covered under warranty by Zenith, which was also
a matter in a lawsuit with the cap maker.
> and generated harder x-rays. The x-rays are only generated while the HV is
> on - they are not residual. Any hazmat must be in the toxicity of the
> phosphors used to generate the colors.
It's the lead in the faceplate glass -- read what I wrote up there.