17 Jul
2008
17 Jul
'08
11:25 a.m.
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