Posted by Jan Panteltje on 11/06/07 20:07

On a sunny day (Tue, 6 Nov 2007 12:20:43 -0700) it happened "Bob Myers"
<nospamplease@address.invalid> wrote in <fgqeu2$5cr$1@usenet01.boi.hp.com>:

>The shortest-lived component in terms of useful service
>life is, of course, the tube itself.

I think not.
I have had a TV repair shop for many years.
CRT replacement is relatively rare compared to other problems,
like HV, bad joints (thermal), dried out electrolytics, etc.


>CRT failures are most
>typically the result of cathode and phosphor aging,

Or bad vacuum.

>so
>rather than quote a time to absolute failure CRT lifetimes
>are most often given in terms of "mean time to half
>(initial) brightness." Typical MTHB numbers, unless
>you've got a tube with a fancier cathode design (VERY
>rare in monitors) are around 15K hours or so, depending
>on the usage profile.

My Samsung Syncmaster CRT did 6 years at 12 hours a day (makes
25632 hours) before I retired it (it is in the attic) this
summer, with NO noticeable decrease in anything (brightness,
white balance, contrast, convergence etc).
Replaced it with a SyncMaster 206BW LCD.
But I always try to treat my monitors nice...
The analog BW portable TV I put with the trash last year
because all went digital here, was from the seventies,
that tube I re-activated myself.... it was no good anymore.

> The rest of the monitor shows reliability
>numbers as would be expected for relatively high-voltage
>analog electronics; something in the range of 20K-30K hours
>for the MTBF used to be typical, although I believe CRT
>monitor overall quality/reliability numbers have been
>dropping recently as the technology became more and
>more relegated to the "economy" end of the market.

My Samsung was from 2000, and reliability has greatly increased
because of better electronics, better HV transformers,
better materials.


>Realistically, I would estimate that the average CRT
>monitor, in typical use, would have a service life of
>something around 5 years, but that's off the top of my
>head - it's been a while since I needed to track CRT fail
>rates as part of my everyday work.

That estimate could be right.
But I must point out that the life expectancy of a fluorescent
tube in a LCD is likely much lower then that of a CRT.
Maybe once LED backlights are more common, things will improve.

A main issue in LCD monitors is, that you are faced with digital
re-size, and digital de-interlace.
This reduces resolution by say half.
As now everybody and their cat seem to go LCD, we need
to think more about progressive (non interlaced) transmissions in my view.
And then I would (and do) use a LCD as reference, not a CRT.
What the broadcasters will do, I dunno, but I do know that the EBU
(European Broadcasting Union) recommends progressive transmissions.
http://www.ebu.ch/en/technical/trev/trev_301-editorial.html
The LCD monitor will then have to have 1920x1080 pixels...

So, with eye on the future, use CRT for sure, but if you
can get some LCDs too, to see what people at home will experience.

LCD does not have the color quality now of fluorescent backlit LCD.
This will improve too with LED backlight.

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