Extreme screen "rot" on an ADM-3a (an ebay auction)

Jules Richardson jules.richardson99 at gmail.com
Thu Jul 17 13:25:42 CDT 2008


Mr Ian Primus wrote:
> I don't know about the terminal picture tubes, or how they're bonded, but I
> do know that this problem also affects old color television picture tubes
> as well. The old color tubes from the late 50's/60's will develop similar
> rot all along the edges, sometimes all the way to the middle. It's referred
> to as "cataracts".

Interesting; I've seen that often on old car windshields - it always seems to 
be at the edges though and without "mould spots", whereas a terminal CRT seems 
just as likely to develop patches anywhere on its surface.

I'm not sure if it's exactly the same breakdown process, or if the 'cataracts' 
one requires an air ingress element, whilst the 'mould spots' doesn't...

> Note that on some color TV tubes (Zenith, IIRC), the bonding compound is
> different and won't come off with a heat gun. Those tubes require
> "persuasion", in the form of a car battery and nichrome wire.

That's the method I used for the HP-250 - it still took a little effort (the 
PSU I had to hand was rather under-spec for the job) but went easily enough.

cheers

Jules




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