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Posted by Bob Myers on 11/07/07 00:36
"Jan Panteltje" <pNaonStpealmtje@yahoo.com> wrote in message
news:fgqhir$v9j$1@news.datemas.de...
> 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.
Read what I said again - the CRT is the shortest-lived
single COMPONENT. The MTBFs of the other
individual components are in generally considerably
longer than that of the CRT's MTHB; it is the fact that
there are so darn many OF them that make the MTBF
of the *assemblies* comparable to that of the tube.
>>CRT failures are most
>>typically the result of cathode and phosphor aging,
>
> Or bad vacuum.
"Bad vacuum" (a leaky or "gassy" tube) in a *monitor*
is almost always the result of mechanical damage, if it shows
up later than the "infant mortality" stage of the tube's life. If a
monitor is just sitting there, it's unusual for the tube to go bad in
that manner. TV tubes are a somewhat different story,
due to their construction and responses to thermal stress.
> 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).
You checked it by eyeball, or did you actually measure the
brightness? Putting a brand-new monitor next to one that's
been in service for a few years is very often a literally eye-
opening experience.
> 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.
MTBFs of CCFL tubes are currently in the neighborhood
of about 20-30k hours, barring mechanical damage; longer-lived
tubes are possible, but at the cost of efficiency/brightness. LEDs
will certainly improve the situation, as long as the number of
individual devices is held within reason.
> 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.
De-interlacing is hardly a concern for PC monitors, unless we're
talking about the "multifunction" or "multimedia" sort of monitor that
also can play TV set and accept standard video. Interlacing all by
itself decreases vertical resolution by a factor of at least 30%, that's
just the nature of the beast.
Bob M.
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