19 Nov
2010
19 Nov
'10
10:39 p.m.
--- On Fri, 11/19/10, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
Is it? I am not convinced. I think in all my classic
computer repairs
I've had one low-emission CRT, and that was in a Mac+. The
picture coul;d
be made bright enough, but there was a curious shaddowing
to the right of
objects on the screen. There as nothing wrong with the
video amplifier
circuit, and a new CRT did cure it.
I've run across several - with low emissions confirmed by my picture tube tester.
Primarily in terminals and coin operated video game monitors. In game monitors especially,
since they were typically left on nearly 24/7, I fairly often see weak tubes that are
pretty consistently weak across all three guns. Also, in television sets, Zenith had a
particularly bad run of tubes in the early 90's - some of which were also in WG arcade
monitors of the era. These will go low emissions across all three guns. Zapping them with
the rejuvinator brings them back... for a little while.
One thing I find in computer monitors is a tube with good emissions but with a burned
face. This seems to be pretty common on Sun monitors used on servers. There will be a
burned, dark rectangle covering the entire screen except for the very edges. No doubt a
result of the white background/black text firmware console display.
Oh, and clean the screen :-). Seriously, I once spent
a day
tracking
down a nonexistant video amplifier fault in a VT100 with a
dim picture
which turned out to b caused by a filthy CRT screen...
Hehe. Reminds me of a television I was given many years ago, it was going to be thrown
away because "the color was no good". Took it home and after scrubbing the
picture tube with glass cleaner, the picture was fine. Shows you what a nasty habit
smoking is...
-Ian