Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!cbatt!ihnp4!chinet!cabbie From: cabbie@chinet.UUCP Newsgroups: comp.sys.atari.st Subject: Re: Screen blanking Message-ID: <1038@chinet.UUCP> Date: Mon, 19-Jan-87 11:18:54 EST Article-I.D.: chinet.1038 Posted: Mon Jan 19 11:18:54 1987 Date-Received: Tue, 20-Jan-87 06:45:12 EST References: <1962@alvin.mcnc.UUCP> Reply-To: cabbie@chinet.UUCP (Richard Andrews) Organization: Chinet - Public Access Unix Lines: 85 Keywords: screen blanking automatic poodles In article <1962@alvin.mcnc.UUCP> ravi@mcnc.UUCP (Ravi Subrahmanyan) writes: This concerns the recent spate of postings of programs that lurk in the innards of our hapless ST's and blank the screen after a few minutes of inactivity. As far as my understanding goes, when the ST blanks the screen, it cuts down the video signal going to the monitor. Now all this would do on a monitor is suppress the beam from the electron-gun and prevent it from striking the screen. So, even though one doesn't see anything on the screen, the gun is still churning out electrons. This therefore saves the screen phosphor, but the gun filament still wears out. Is this a consideration? Would turning down the brightness and contrast in addition to letting the program blank the screen be any better (I don't think so)? From what I remember from my oscilloscope days, the life of the filament is as important as that of the phosphor, ie. picture brightness is a function of both and so saving on one may not be helping as much as we may believe from the blanked screen. Or, are these just the blabberings of an outdated education (after all, I >am< almost in my mid-twenties.. oh, those days of youth.. gone forever! (sigh :-) -ravi With all of the ramblings on and on about color monitors and why you should blank the screen/turn off the monitor/rotate the colors/etc. ad nauseum, I have to express my own observations. Some time ago an article was published in the "Computer Shopper" in regards to this. In summary the author stated that turning off the monitor was bad for the CRT because the constant heating and cooling of the filament would cause eventual failure of the filament itself. The basis of this was a standard household light bulb. Not true! I have been in the video business for several years now and have yet to see a filament fail under those condi- tions. I can truthfully say that I have only seen 1 CRT filament that was open and I don't know if that was done on purpose (115 VAC applied to the fila- ments?). I have seen 1 Plumbicon tube with an intermittent heater connection and that tube was questionable at best. At the TV station where I work we have several monitors (15-20) that have been on 24 hours a day seven days a week for the last 8 years now and have no problems with the CRT's on any of them. The CRT's do get weak after several years but we do have a rejuvenator that solves that problem at least temporarily. I have worked prior to that in several TV shops where the TV sets were turned on and off several times a day and have experienced no problems with this type of operation either. There is an advantage to blanking the screen when not using the monitor for an extended period of time (read 15-60 minutes). To prevent the image from getting burnt onto the screen one should blank the screen after about 10 minutes of non-use. Turning the monitor on and off several times a day will not hurt the CRT either. The most common CRT problems are: 1) Cathode shorts (bad manufacture/design) 2) Gassy tube (old age) 3) Burnt phosphor due to exposure to direct sunlight 4) Anode (HV) shorts (relativly rare) 5) Weak tube due to age and/or use. 6) Burnt phosphor due to excessive brightness Yes even Sony trinitrons are subject to failure. I have replaced several of them due to any of the above conditions. The technology of monitor and television design has increased over the last several years. The most common failure now is the Horiz. output transistor and or the rectifiers to provide 150 VDC for the horizontal section. Occasionally a horiz. output transformer will go bad but that is not too common any more. The sets that had a real problem was certain RCA and Sylvania sets. Zenith had a problem with a capacitor on their chromacolor II sets that would allow the HV rise to unbelievable levels. (one was documented at 58kv) But that is another story. (War story? (:>) ) Ravi, don't take this as a flame. Your article just happened to be a good place for me to express my experiences. In summary this entire subject has caused much unneccessary concern. If unattended, the monitor screen should be either blanked or the entire monitor should be shut off depending on how long the monitor will be left un-attended so as to prevent burning of the phosphor. -- ******************************************************************************* Any opinions expressed above are my own. Rich Andrews They can be yours too. Please send $19.95 to.....ihnp4!chinet!cabbie *******************************************************************************