YouTube video to repair screen rot

Tony Duell ard at p850ug1.demon.co.uk
Tue Mar 3 13:22:17 CST 2009


> 
> Richard wrote:
> > Well, the previous discussions along this line talked about removing
> > the laminated front with a nichrome wire.  I believe at least one list
> > member reported using this technique.
> 
> I did it with an HP-250, but that was for a non-functional system (i.e. it 
> needed to look as nice as possible, but increased implosion risk was not a 

I hope that machines is not on public display anywhere. If that CRT 
implodes you could have _big_ problems...

I don't see it matters where the machine is goign to be powered up or 
not. The imposion risk is there allthe time.

> factor) - hence there's currently just an air gap between CRT and faceplate on 
> that particular machine. For that tiny screen, I got enough juice (just) from 
> a plain old PC power supply to cut through the failed sealant.
> 
> (One day that machine almost certainly will get restored to working order, but 
> not in the near future I suspect)

Pity... I believe it's quite an interesting machine.

> 
> > Maybe there's an easy way to keep the thickenss uniform and then you can 
>  > repair the safety as well as the appearance.
> 
> Personally I've used a lot of 70s and later machines and never known a tube 
> implode - I think for my own use I'd be tempted not to screw around with 

Nor have I (and I've got CRTs a lot older than that). But it must be a 
risk -- after all TVs had imposion screens going back at least to the 
1950's, and there was much liess of a 'safety culture' back then. But I 
guess the danger was enough for manufacturers to do something about it.

The pre-WW2 UK TVs, which often haf the (small deflection angle) CRT 
mounted vertically and an inclined mirror in the lid of the cabinet to 
view it by, didn't have imposion protection AFAIK. I wonder if experience 
from WW2 had something to do with it -- I am told there were injories 
caused to airbourne radar operators who were looking down a viewing hood 
at the radar CRT, the plane had a heaving landing, was shot at, etc, and 
the CRT imploded.

> replacing the sealant (subject to next owner knowing what they were getting, 
> of course). I wouldn't want to risk it for anything "public" though.

Well, I am not a particulalrly safety-concious person, I will work on 
CRTs, etc with no problems. But I wouldn't want to sit in front of a CRT 
where the implosion protection had been downgraded.

-tony



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