"screen mold"

Tony Duell ard at p850ug1.demon.co.uk
Wed Oct 5 15:38:17 CDT 2005


> 
> The (plastic) faceplate is *not* an implosion protection, it is a contrast 

Are we talking about the same thing? I am not talking about the thin 
plastic anti-glare filter that's a seprate part and fitted between the 
CRT and bezel in some monitors. I am talking about wat seems to be a 
second glass layer that is bonded to the CRT (and not just round the edges.

> and anti-glare plate. All (TV) picture tubes since around 1968 have an
> implosion protection that is integral to the tube and not simply glued on 
> top of it.

It was assembled to the CRT at manufactuer (i.e. not when the CRT was put 
into the monitor). I am not convinced it couldn't be part of an imposion 
protdction system.

> Second, a CRT won't just implode on its own (that's a fairy tale). The 

I am certainly not convinced of this....

Every TV, monitor, etc since the war has had some kind of imposion 
protection. This must have cost something to provide, it would not be 
done if it wasn't necessary (note that even the cheapest TVs still have 
it). An implosion might be rare, but it was surely a real risk.

> front screen really needs a very big shock before it cracks. The most 
> fragile part of a CRT is the section from the conus to the neck of the 
> tube. And if the neck should break the rest won't implode, the parts are 
> just too solid. There were several companies in the old days who removed 
> the neck of a used CRT and replaced it with one with a new gun system.

Absolutely. And they did so with great care. Even just cracking off the 
tip of the pinch-off tube was not suitable for this, the inrush of air 
would damage the phosphor coating on the screen (next time you throw out 
a defective CRT and crack the pinch-off tube to let the vacuum out, look 
at the screen afterwards). There were various ways of doing it, but all 
basically let the air in slowly.

-tony



More information about the cctalk mailing list