I posted a similar thread at V.K. in twenty-10 and got some interesting replies. Been at it again.... have a GTE Philco b/w from 1978 playing nonstop in the garage...six months on and it looks as bright as when I got it(curb find)....This t.v. was chosen by me since it has relatively low power consumption. Wonder if a tube-type chassis would still be playing after these months.
Curious as to what happens to high voltage during blanking state.
anyone have a 'record' of how long a crt based monitor has been powered./?

Not sure what you're asking but this is how we operated studio equipment, 24-7. I did issue a memo not to leave colorbars punched up overnight as they burned phosphors prematurely.

Sounds like a great recipe for a burned down garage , if ya ask me ...... Remember , the TV station monitors Arbilab mentioned were probablly ALOT newer than 30 + years old when they were leaving them on 24/7 , and being in a commercial building , there were most likely fire sprinklers in place .......

...... At 3 am some morning , when this "experiment" goes up in smoke , who's gonna be around to put out the flames ?????

There is a REASON why anyone with half a clue advises to NEVER leave vintage electronics running unattended !!!!!!!!

highly doubt the set will engulf in flames. If the garage burns I'll rebuild it with lumber and nails.

I was thinking however, if the vertical fails at 3AM some morning, that crt will have a bad phosphor burn line!

Agreed, as long as it's fused properly you are fairly safe, plus consumer electronics was required to be built using flame retardant materials since the late 60s... This was due to a rash of fires in the smaller all tube color portables...

My Hitachi 50" projo had a vertical problem due to the coupling fluid leaking from one of the CRT/lens assembly(no doubt a unanticipated condition)... Those are supposed to blank the video if vert is lost, mine didn't... It instantly seared the phosphor, leaving apparently a melted pattern in the face of the CRTs...

Not a CRT but I run at least one of my tube transmitters 24/7, the most used one has been going almost continually for around four years... I do shut it down if I'm going to be away for a day or more, but being retired I'm here almost 24/7... Of course it's lightly fused and doesn't draw but a few ma current, most of that is for the tube heaters... After approx three years I tested the tubes and found the 12AU7 1st audio/osc weak and shorted, the other tube was fine but had nowhere nearly the usage...


Tom

Ok , If you aint worried about the fire risk , that's your choice to make .... Were it me , I'd never feel comfortable leaving something that old running 24/7 , but then I guess everyone's comfort level is different regarding such matters . I truly pray you never have a fire with it , I really do , , But if you do , at least I take comfort in knowing I tried to warn ya ........

And as far as a vertical drive failure goes , , heck ya , I'll bet the burn line would be as deep as the grand canyon

hey guys.. i just re-read this and I didn't mean to come off as an assh*le. I realize it's a wasteful, somewhat dangerous endeavor but I'm really interested in this stuff.

Soo... today I went up into the attic to check things out. Nothing has changed. I brought an ATSC converter box up there to pick up over the air signals... The picture is quite good still.. The CRT is a Taiwanese "Philco" and I couldn't find any EIA number.
I might just retire this experiment. What do you think.

I have seen b/w monitors for guard stations in buildings run 3-5 years. 24/7. By the 4th year they are getting dim, lacking focus or exhibit gas problems. When the guard could no longer recognize faces the monitor was replaced. Some expired prematurely from the concentration of tobacco smoke or spilled coffee, a few, from the effects of a nearby lightning strike...

Chas

I'd try to build some sort of a rig that controls the power to the set with a latching relay whose coil was connected to a smoke detector such that it the detector tripped the power to the set would be cut. You can probably build something like that for what you have in your pocket and or junk box, and it will be FAR cheaper than a new garage (unless of course you hate your garage and want an excuse to build a new one).

This should make this test safer.

If the set was not used all that much in the past, your experiment might need to go for several years before the CRT starts to die. In some households (definitely not mine), the TV is on 10 hours a day, and such sets sometimes last more than 10 years on this schedule. After a few decades of improvement in CRTs, the lifetime of CRTs was pretty good by the time this set was made. Earlier CRTs from the 1950s and 60s didn't seem to last nearly as long.

Bottom line is that this could be a pretty boring experiment for the next couple of years.

And I wouldn't be overconfident about the rest of the TV not experiencing some problem that causes a fire... Not a huge risk, but definitely some.

I always advise people not to leave old radios and TVs running when they are out of the room.

I work in an airport, where most monitors are on 24 hours per day, 7 days per week. There are still a number of CRT monitors in use, and though few if any of them have lasted more than 5-10 years without needing circuit repairs, there are quite a few that have been in use since 1979, including a few with their original CRTs (though they are not as sharp or bright as a new one). I did find one of these monitors less than ten years ago that had not been repaired since I took over this job in 1984.

Hmm,,I guess it will be hard to kill this set
Maybe I'll turn the volume wide open and short the speaker terminals together. Or block up all the ventilation ports. Or wire the crt heater for 9v...

JUST KIDDING on all counts, by the way.

Why would anyone leave a TV set on 24/7 if they weren't planning on watching it? Waste for the sake of waste? And to do this to a vintage TV... Why?

First off, why? Because, as a collector of vintage televisions and monitors who understands the fundamental function of these apparati, I have decided to determine how long a typical NTSC monochromatic receiver from the late 1970s will last under less-than-ideal circumstances.

It isn't a waste when people over eat, over smoke, over drink & over fly.

If someone has the means to do something, you needn't get in the way of that, nor should you protest it. This is one MAJOR issue with politics today.

This is not a set anyone would call valuable today, and I would guess that will not particularly change 50 years from now. Ok to experiment destructively with a few sets here and there. This isn't an experiment I'd be particularly intersted in doing, but I don't mind someone else doing it, and learning what the result is.

Back to the studio, where nothing was ever turned off.

These were industrial products, Tektronix. One under repair test on the bench caught fire. Yes, flames. It destroyed itself. Fortunately it did so during business hours and it didn't destroy the building. Yes we had sprinklers but wetting a million dollars worth of operating instrumentation is still a million dollar loss in hardware alone. Not counting loss of utility.

CRTs in the plant were good to ~3 years emissivity. They would stilll light up past that but not linearly. That is, they were no longer useful as color references. Yes I know you're talking about a B/W, but emissivity is emissivity. So based upon the life cycles of roughly 100 CRT monitors, the useful life of CRTs is 26,000 hours. They can be milked beyond that if one is willing to accept compromised performance.

From my broadcast experiences:

One of our DTV transmitters uses whats called an Inductive Output Tube and the two of them have now operated for over 75,000 hours since 1999. 42KW TPO.

The CRT monitors which are now filling a parking garage waiting for recycle worked to the end but if they were turned off they were slow to come on. The B/W monitors all have some screen burns.

In the really old days the early RCA TM-5 monitors would catch fire if the source of horizontal drive failed during the night when no one was in the studio.

Jim

We had HP Green screen monitors that ran for 8 + years. They were a plant-wide access screen that
a bottom line with Function key promps. After years, even when switched off the phosphor had the
login pattern burned in. That old system stayed running until PCs appeared and the plant system used
DOV modems connected to the same phone lines that the old monitors used.

The Clone IBM PCs, and their monitors were cheaper than what HP charged for those monitors.

And we could play Tetris on them

I leave my Tv and computer monitor on all the time, 24-7-365 90% of the time. However them are alot newer. My computer monitor is a 2004 model, and ive had it almost 3 years and its rarely been turned off,except when i had no computer for a short time and when my linux OS would power the monitor down. The way i see it, theres no sense of turning it off unless its going to be off for more then a few hours. On one of my older tvs, when someone would suddenly start turning it off after its been on for an extended period of time, shortly after that it just up and quit working. However, i am in front of my tv quite a bit. As far as tube electronics, i will only turn them on when i'm using them and if i leave the house i turn them off. I know how warm they run.

A friend gave me a B&W TV with an instant-on circuit that kept about 3 volts on the picture tube heater, and that set was very dim. I removed the instant-on to save electricity, and the set took a long time to warm up to its usual dim picture. It seems even without HV, keeping the heater on wore the set out. I got rid of it.
Don