CRT monitor modeswitching

I remember seeing old MAG monitors with an LED display (digits) telling you what mode it is in currently, it could save 10 modes I believe for various resolutions.

It had a relay.

Well you figure, when you turn on your computer at POST, it is in a different resolution, when I boot up Winslows, it changes resolution again, when I play my favorite games, it changes to an even higher resolution. My monitor was made in 1994!!!!!! (archaic piece of junk, pre Energy saver), and it is still kicking!!! (on this machine, which is used daily)

Could be just coincidence.

I suppose resolution modes can be switched via "soft" switching, or relays, mine uses soft switching and hasn't ever failed (Daewoo near flat CRT)

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Myron Samila
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Samila Racing
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Some models use a relay to switch some component configurations in the scan circuits for the different scan rates. There is nothing wrong with this. The newer monitors use electronic switching.

In a properly designed monitor, there is no excessive wear by changing modes. The fact is, that since you are using older monitors that are used in the first place, the failure rate is probably higher because of age, not how they are being used.

It is a fact that these monitors will run for only a certain amount of hours in their lifespan. There is something called MTBF "Mean Time Between Failure". In the lower end of the monitors, this factor is not published. Usually manufactures will not make a determination of this spec, because there is an added R&D cost involved. They are only interested that the monitor will last a bit more than the warranty period.

The MTBF for most of the CRT's (picture tubes) is about 30,000 to 40,000 hours. Under normal use, this is about 4 to 6 years. The life span of the electronics to keep up their performance is about the same. This is why after about 4 years, if the monitor is still working properly, it is a good idea to sell it while it is still working. This is how you can find so-called good deals on monitors, which in reality it is not a good deal, because it has reached its MTBF factor.

If you were to buy a new monitor, you will find that you can run it for a bit more than 4 years with reasonable reliability. After that period the CRT may be a bit soft, and the scan accuracy may not be the same as when new.

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"Halfgaar"  wrote in message
news:c5mjmf$31g$1@news1.tilbu1.nb.home.nl...
I was wondering, is modeswitching harmful for a CRT monitor? And when I say
harmful, I mean that when you mode switch about a dozen times an hour, that
an average second-hand monitor will only last a month? I ask, because I
friend of mine switches back and forth from Linux textmode to GUI-mode, and
he has destroyed two second hand monitors in a relatively short time; the
second within a month, the first I don't know. I asked if he had grounded
them to an earth, and he had.

And another thing; in some monitors, you can hear relays switching when the
monitor switches mode. What is this, and why do some monitors do this, and
others don't? Someone once told me that a when a monitor has such a relay,
that it is a sign of quality. Is there any truth to that?

TIA

My few months old Eizo T766 19" CRT also uses a relay. At least, I hear something ticking when switching mode. But, not always. Only when switching from certain modes to certain others.

It was not about my monitor(s), but a friend's.

I know of the MTBF rating. The MTBF of a Philips 109P40 I used for a year (long story) had one of, I qoute, ">75000 (CRT excluded)". Strangly enough, I can't find anything about an MTBF rating of this Eizo model, even though I remember having seen it somehwere, but perhaps I'm confused with the

109p40. Anyway, one cannot say that this is because Eizo is lower end and I excpect it to last as long or longer than a Philips 109P40. Both of them BTW have a automatic color calibration to compensate for wear of the CRT. And as for the loss of scan-rate precision; isn't it so that when a CRT starts to loose scan-rate precision, it'll be dead soon?

My Eizo BTW has a Sony Trinitron CRT, do you know anything about it's MTBF? I can't find it anywhere.

And as for the failings of my friends monitors, I'll tell him what you said.

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Not without a special cathode, it isn't. With a standard cathode of the type typically seen in monitor CRTs, the mean-time-to-half-bright (the tube itself generally is spec'ed in MTHB, since aging of the cathode/phosphor is the dominant wearout mechanism, once the "infant mortalities" are out of the picture) is about 10-15k hours. However, with average use (call it about 2,000-2,500 hours per year), you're still in the 4-6 year ballpark. A tube left on round-the-clock, of course, doesn't make it that long.

the

Most often, the relays you hear are switching components in and out of the horizontal deflection circuits, to set up for different sweep frequency ranges. More recent monitors tend to do that sort of switching electronically, but it makes little difference one way or another. There IS a bit more stress on the monitor when switching modes, but the effect on the overall life expectancy is generally insignificant. If you're just switching a half-dozen times an hour, I wouldn't worry too much about it.

Bob M.