1 Mar
2009
1 Mar
'09
1:57 p.m.
On 28 Feb 2009 at 19:20, eric wrote:
I believe that front glass screen ws some kind of laminated glass (like a
car windscreen) so that it wouldn't shatter if the CRT imploded.
Most modern CRTs -- including ones used in classic computers, have some
kind of intenral implosion protection. Either a laminated faceplate (2
layers of glass onded together) or a tension band, or both.
I say 'most' becuase there are a few that don't. In genearal electrostat
'scope tupe CRTs don't have any internal implosion protection. And the
little electromagnetic CRT used in the HP9826 doesn't either (it relies
on the plastic anti-glare screen) -- this is mentioned in the HP manuals,
and I've confirmed it hwen I took my 9826 apart.
This may be rhetorical, but why did they use that
PVA material in the
first place, given that the solution provided in the video just places
the lens over the CRT glass with nothing but air in between?
In the beginning, many manufacturers simply placed the CRT behind a
flat sheet of safety glass (my family's 1952 RCA set was that way).
The idea was to protect the viewer if the tube were to implode (had
been known to happen).
I suspect some sort of bond between a rather thin glass lens and the
face of the CRT itself comprises the needed protection (weren't the
early RCA versions of this called "Pan-o-ply"?). Without the bond,
I've head the term 'Panoplex' relating to a CRT with some kind of
internal implosion protection (i.e. one that doesn't need a safety screen
in front of it). I can't remember which company used that name, though.
an imploding CRT would likely shatter the lens also.
So, while this
gets rid of the "cataract", I think there's a compromise in safety.
Yes, this would worry me also. Unless you know the exact reason for how
the CRT was originally assembled, I would have though you shouldn't
change anything.
-tony