M
Mxsmanic
Today I bought a new monitor. My eight-year-old Sony 20" Multiscan IIe
finally scanned its last raster on Thursday, after some 30,000 hours of
faithful service.
I find myself wondering nostalgically what finally killed the CRT. Over
time, of course, it had gradually gotten darker and a tiny bit fuzzier.
The convergence and geometry and color balance were remarkably constant
right up until the very end. But the brightness and contrast gradually
diminished, and during the last 90 days or so, they started to decline
fast, with frequent shifts in the RGB output.
My assumption is that the electron gun itself was simply worn out, no
longer able to produce a copious supply of electrons for the tube. I
don't recall if this tube had three guns or one (perhaps three, if the
RGB balance shifted randomly). Eventually the screen got so dim that I
had to turn down other monitors and turn off lights in order to read it.
The real mystery for me, though, is why it finally failed abruptly. A
few weeks ago there was a power failure, and the CRT was off for two
hours and cooled down completely (instead of just being on power-saver
standby). It took 2.5 hours for it to come on again, but when it
finally did, the image became visible quite abruptly, over a period of
about 2 seconds. What I don't understand is why the screen was dark for
2.5 hours (no trace of an image), and then _suddenly_ the screen came on
and looked okay.
Doesn't a failing tube simply get darker and darker? Wouldn't a tube
that takes a long time to warm up just fade into visibility very
gradually? Why did the tube stay dark for hours, then abruptly produce
a visible image?
It's mostly academic now, but I've been trying to figure out why it
behaved this way. Any ideas?
finally scanned its last raster on Thursday, after some 30,000 hours of
faithful service.
I find myself wondering nostalgically what finally killed the CRT. Over
time, of course, it had gradually gotten darker and a tiny bit fuzzier.
The convergence and geometry and color balance were remarkably constant
right up until the very end. But the brightness and contrast gradually
diminished, and during the last 90 days or so, they started to decline
fast, with frequent shifts in the RGB output.
My assumption is that the electron gun itself was simply worn out, no
longer able to produce a copious supply of electrons for the tube. I
don't recall if this tube had three guns or one (perhaps three, if the
RGB balance shifted randomly). Eventually the screen got so dim that I
had to turn down other monitors and turn off lights in order to read it.
The real mystery for me, though, is why it finally failed abruptly. A
few weeks ago there was a power failure, and the CRT was off for two
hours and cooled down completely (instead of just being on power-saver
standby). It took 2.5 hours for it to come on again, but when it
finally did, the image became visible quite abruptly, over a period of
about 2 seconds. What I don't understand is why the screen was dark for
2.5 hours (no trace of an image), and then _suddenly_ the screen came on
and looked okay.
Doesn't a failing tube simply get darker and darker? Wouldn't a tube
that takes a long time to warm up just fade into visibility very
gradually? Why did the tube stay dark for hours, then abruptly produce
a visible image?
It's mostly academic now, but I've been trying to figure out why it
behaved this way. Any ideas?