Running CRTs without implosion protection glass

tony duell ard at
Fri Jul 1 13:44:43 CDT 2016

> I know a few list members who have been doing this, after fixing CRT
> cataracts.
> Was that glass additionally leaded to cut down on X-rays at all? Is there a
> risk to that?

It probably was leaded glass, but mono CRTs only run at about 15kV on the
final anode. I don't think you get much of an X ray risk from that. 

The older TV CRTs (at least in the UK) had a separate implosion guard that
was either a sheet of laminated glass, or later on a tough plastic sheet or 
'bowl'. I don't think those (particularly the latter) would be much of an X ray
shield, nor do I ever remember seeing warning about X ray hazards when
repairing such sets (which might involve running the CRT out of the cabinet,
and thus without the shield in place.

Colour CRTs might be a different matter. AFAIK all the ones used in the 
UK TVs had integral implosion protection so there was never any suggestion
that they could be run without that. And they run at 25kV EHT. I do remember
reading that the EHT rectifier diode valves and shunt stabiliser triodes in early
colour TVs gave off enough Xrays to be dangerous, I never saw similar
warnings about the rectifier valves in monochrome TVs. 


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