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A Sony' CRTs color is screwed up.
I have a Sony 19" desktop tv, about 20 years old, which gave a perfect
picture since I got it 10 years ago, until I went on vacation 10 days ago. I was gone for 8 days and when I got back the picture was weird. There are no ghosts but the colors are screwed up. OTOH a picture transmitted in black and white is pretty good, still black and white. But with a color picture, in some parts of the screen at least, the blue has become pure green and the red has become pure blue. A medium blue background has become all green except for a 2" red circle on the outer parts of the screen, and blue at the corners. Despite this, as a tv show progresses, there seems to be less red than normal, mostly some pink, and skin tones are all wrong. Probably everything is wrong. I was a moderately successful amateur repairman in the days of tubes, and I did some other repairs besides just changing tubes, but tv's have gotten a lot more complicated. Any chance I can fix this? Even if I can't, I'm curious what sort ol failure causes these symptoms? And would I have been better off leaving the tv on for 8 days, or putting it on a timer, than letting it sit that long. It seems to me that a lot of tvs and vcrs have failed when not used for months. Thanks. |
A Sony' CRTs color is screwed up.
Sounds like a purity problem. Start by degaussing it.
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A Sony' CRTs color is screwed up.
micky wrote:
I have a Sony 19" desktop tv, about 20 years old, which gave a perfect picture since I got it 10 years ago, until I went on vacation 10 days ago. I was gone for 8 days and when I got back the picture was weird. There are no ghosts but the colors are screwed up. OTOH a picture transmitted in black and white is pretty good, still black and white. But with a color picture, in some parts of the screen at least, the blue has become pure green and the red has become pure blue. A medium blue background has become all green except for a 2" red circle on the outer parts of the screen, and blue at the corners. Despite this, as a tv show progresses, there seems to be less red than normal, mostly some pink, and skin tones are all wrong. Probably everything is wrong. I was a moderately successful amateur repairman in the days of tubes, and I did some other repairs besides just changing tubes, but tv's have gotten a lot more complicated. Any chance I can fix this? Even if I can't, I'm curious what sort ol failure causes these symptoms? And would I have been better off leaving the tv on for 8 days, or putting it on a timer, than letting it sit that long. It seems to me that a lot of tvs and vcrs have failed when not used for months. Thanks. The laziest first step is try degaussing it, or make sure the degausser still works. Is the nasty thud and buss present when you fire up the set from being cold and off? It's been said lightning strikes can magnetize a TV chassis enough to mess up colors, but I have no first hand experience with that. TVs have so little metal even scrappers don't want them. A 19" television from 20 years ago won't have one of those north/south hemisphere detector chips, so it's probably not that thing. |
A Sony' CRTs color is screwed up.
"William Sommerwerck" wrote:
Sounds like a purity problem. Start by degaussing it. A purity problem would NOT have black and white looking ok as reported in the original post nor would it result in explicit color replacements as reported. Sounds like a color demodulation problem. |
A Sony' CRTs color is screwed up.
"Smarty" Sounds like a purity problem. Start by degaussing it. A purity problem would NOT have black and white looking ok as reported in the original post nor would it result in explicit color replacements as reported. ** The set is a 19 inch Sony - so it is a Trinitron type. I suspect the behaviour is typical of Triniton with a magnetised aperture grille. The degaussing thermistor may have failed in the set and at the instant of failure left with a parting blow by magnetising the grille. The OP can check for this by noting if the usual switch on " bong" noise still happens. He can also bring a magnet near ( not touching) the screen and see if that tends to fix various areas. Sounds like a color demodulation problem. ** Not likely. .... Phil |
A Sony' CRTs color is screwed up.
On Jun 1, 8:19*pm, "Phil Allison" wrote:
"Smarty" Sounds like a purity problem. Start by degaussing it. A purity problem would NOT have black and white looking ok as reported in the original post nor would it result in explicit color replacements as reported. ** The set is a 19 inch Sony *- so it is a Trinitron type. I suspect the behaviour is typical of Triniton with a magnetised aperture grille. The degaussing thermistor may have failed in the set and at the instant of failure left with a parting blow by magnetising the grille. The OP can check for this by noting if the usual switch on " bong" noise still happens. He can also bring a magnet near ( not touching) the screen and see if that tends to fix various areas. Sounds like a color demodulation problem. ** Not likely. ... * Phil What Phil says. I did color tv repair for 20+ years, and it is amazing what magnetization can do. If there was a lightning storm while you were gone, that would explain a lot. |
A Sony' CRTs color is screwed up.
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A Sony' CRTs color is screwed up.
On Saturday, June 1, 2013 4:54:09 PM UTC-4, Smarty wrote:
"William Sommerwerck" wrote: Sounds like a purity problem. Start by degaussing it. A purity problem would NOT have black and white looking ok as reported in the original post nor would it result in explicit color replacements as reported. Not true. Purity problems are most apparent when the chroma is on. If one looks carefully, the purity problem does exist in the black and white image, but it's just no where near as apparent. Sounds like a color demodulation problem. A color demodulator problem would cause incorrect colors, but I've never seen one cause localized errors as the OP pointed out. Most likely the dual degaussing thermistor is either bad, or has one lead detached from the board. |
A Sony' CRTs color is screwed up.
"Smarty" "Phil Allison" "Smarty" ** The set is a 19 inch Sony - so it is a Trinitron type. I suspect the behaviour is typical of Triniton with a magnetised aperture grille. The degaussing thermistor may have failed in the set and at the instant of failure left with a parting blow by magnetising the grille. The OP can check for this by noting if the usual switch on " bong" noise still happens. He can also bring a magnet near ( not touching) the screen and see if that tends to fix various areas. This is altogether surprising to me, but then again I virtually never did TV repair. ** I did - in the B&W days in Australia, circa 1972 and onto to 1976. But it never grabbed me. I have a bit of trouble understanding why a magnetized shadow mask or aperture grill would still allow a black and white image to be correctly displayed. If beam alignment were 'spoiled' by residual magnetic contamination of the CRT near the faceplate or if the purity rings were not doing their job, then the outcome should be color blotches regardless of whether chroma saturation is absent or present. I hope this specific problem is eventually solved so I can hear the actual cause of the problem. This old dog loves to learn new tricks ! ** Once, I was optimistic enough to buy an "re-conditioned" ( = re-gunned ) 26 inch colour tube for my own TV. It was a regular, three stripe, full convergence, colour Toshiba CRT with removable yoke dating from the early 1970s. The tube supplier wanted the old tube back so I had to have it out of the set and ready - the exchange took place around 11AM. I fitted the tube that afternoon and after a heck of a lot of work was able to watch my favourite TV programs the same evening. Doing a full convergence "ab initio" on an aging and rather heavy TV set is not for the faint hearted - but the set served me damn well for another 10 years. Interesting that electron guns cathodes ( particularly the red one ) wear out long before phosphors on the tube face are history. ..... Phil |
A Sony' CRTs color is screwed up.
On 6/2/2013 7:23 AM, John-Del wrote:
On Saturday, June 1, 2013 4:54:09 PM UTC-4, Smarty wrote: "William Sommerwerck" wrote: Sounds like a purity problem. Start by degaussing it. A purity problem would NOT have black and white looking ok as reported in the original post nor would it result in explicit color replacements as reported. Not true. Purity problems are most apparent when the chroma is on. If one looks carefully, the purity problem does exist in the black and white image, but it's just no where near as apparent. Sounds like a color demodulation problem. A color demodulator problem would cause incorrect colors, but I've never seen one cause localized errors as the OP pointed out. Most likely the dual degaussing thermistor is either bad, or has one lead detached from the board. I have not dealt at all with magnetized Trinitrons / aperture grills, and only have very limited experience with magnetized conventional CRTs but purity problems certainly were visible in the black and white images of those needing degaussing. It did not take moving color images to suggest purity / magnetization nor did it take careful inspection. The other, even more confusing original post issue was the non stationary nature of the color shifts, and the fact they were reported as moving with the displayed image, again evidence that the problem was not a purity problem. I gladly defer to the experience and judgement of those who repair TVs. My experience is limited to building a Heathkit color set a million years ago and repairing my Advent and Kloss projectors, not using or needing any purity control whatsoever! |
A Sony' CRTs color is screwed up.
On 6/2/2013 8:34 AM, Phil Allison wrote:
"Smarty" "Phil Allison" Interesting that electron guns cathodes ( particularly the red one ) wear out long before phosphors on the tube face are history. .... Phil I recall vaguely that the rare earth material from which red phosphors were created was comparatively inefficient, unstable, and expensive. I think it might have been ytrium but I may have the name wrong. Zenith and others many decades ago proudly introduced newer and more advanced red phosphors but I would not be surprised that they wore out faster. |
A Sony' CRTs color is screwed up.
"Smarty" wrote in message ...
I recall vaguely that the rare earth material from which red phosphors were created was comparatively inefficient, unstable, and expensive. I think it might have been ytrium but I may have the name wrong. Zenith and others many decades ago proudly introduced newer and more advanced red phosphors but I would not be surprised that they wore out faster. This broad error about red phosphors has been repeated many times in this group. Many people here grew up during the introduction of rare-earth phosphors, so it's hard t understand why the error persists. The original red phosphor had low output and turned orange-ish when pushed. The rare-earth red phosphor -- introduced in the mid-60s (I think) -- had greater output and more-consistent hue. It might have deteriorated faster (I don't know), but //it// was the advanced phosphor -- not the phosphor that preceded it. I specifically remember a radio program sponsored by Sylvania that promoted these new phosphors as bringing color TV "out of the dark ages". |
A Sony' CRTs color is screwed up.
On Sunday, June 2, 2013 1:15:58 PM UTC-4, Smarty wrote:
I have not dealt at all with magnetized Trinitrons / aperture grills, and only have very limited experience with magnetized conventional CRTs but purity problems certainly were visible in the black and white images of those needing degaussing. It did not take moving color images to suggest purity / magnetization nor did it take careful inspection. Perhaps your experience is with the old delta gun arrangement, which were prone to more purity error and more severe error. But I can tell you that with modern in line arrangements (Sony being no exception), bad purity is not always obvious in black and white pictures. The other, even more confusing original post issue was the non stationary nature of the color shifts, and the fact they were reported as moving with the displayed image, again evidence that the problem was not a purity problem. I reread the OP's post several times, and don't see what you mean by non stationary color shift. From what I read, the purity error was static on the screen. I'm not a betting man, but I'd bet that if the OP degausses the TV, the problem will go away. |
A Sony' CRTs color is screwed up.
John-Del wrote: On Sunday, June 2, 2013 1:15:58 PM UTC-4, Smarty wrote: I have not dealt at all with magnetized Trinitrons / aperture grills, and only have very limited experience with magnetized conventional CRTs but purity problems certainly were visible in the black and white images of those needing degaussing. It did not take moving color images to suggest purity / magnetization nor did it take careful inspection. Perhaps your experience is with the old delta gun arrangement, which were prone to more purity error and more severe error. But I can tell you that with modern in line arrangements (Sony being no exception), bad purity is not always obvious in black and white pictures. You may not believe this, but some TV stations continued to use Delta gun CRTs for their master monitor, and Trinitron for all of their other monitors. The 'delta' master monitor was a little over $7,000 in 1988 for the station I worked at. The two new Trinitrons were $1,700 each. |
A Sony' CRTs color is screwed up.
On 6/2/2013 2:14 PM, John-Del wrote:
Perhaps your experience is with the old delta gun arrangement, which were prone to more purity error and more severe error. But I can tell you that with modern in line arrangements (Sony being no exception), bad purity is not always obvious in black and white pictures. The other, even more confusing original post issue was the non stationary nature of the color shifts, and the fact they were reported as moving with the displayed image, again evidence that the problem was not a purity problem. I reread the OP's post several times, and don't see what you mean by non stationary color shift. From what I read, the purity error was static on the screen. I'm not a betting man, but I'd bet that if the OP degausses the TV, the problem will go away. Thanks John for the further clarifications. My experiences in this regard are so very limited that the only cases I have seen cause static, noticeable blotches, visible in black and white at least as much so as in color. They also do not agree with the OP comment: "As a tv show progresses, there seems to be less red", suggestion that the color error was not a static problem which (again in my very limited experience) is not the way a magnetic bias displays itself. For the very few situations I have personally dealt with where degaussing ***was*** the issue, such as after building a Heathkit from parts, or moving a TV from one room to another, the purity issue manifested itself the same, namely, static, highly visible blotches, both in the color and black and white displays. The black and white impurity effect, if anything, was much more obvious, owing to the masking and obscuring of color errors in a highly colorful program. (Same comment regarding convergence errors or for that matter most errors.) I entirely concede that this may be totally a color purity problem caused by magnetizing, and sincerely thank you and the group for enlightening me in this regard. |
A Sony' CRTs color is screwed up.
On Jun 2, 12:39*pm, "William Sommerwerck"
wrote: "Smarty" *wrote in ... I recall vaguely that the rare earth material from which red phosphors were created was comparatively inefficient, unstable, and expensive. I think it might have been ytrium but I may have the name wrong. Zenith and others many decades ago proudly introduced newer and more advanced red phosphors but I would not be surprised that they wore out faster. This broad error about red phosphors has been repeated many times in this group. Many people here grew up during the introduction of rare-earth phosphors, so it's hard t understand why the error persists. The original red phosphor had low output and turned orange-ish when pushed. The rare-earth red phosphor -- introduced in the mid-60s (I think) -- had greater output and more-consistent hue. It might have deteriorated faster (I don't know), but //it// was the advanced phosphor -- not the phosphor that preceded it. I specifically remember a radio program sponsored by Sylvania that promoted these new phosphors as bringing color TV "out of the dark ages". Even after the introduction of the rare-earth phosphors, the red phosphors were less efficient and the red electron gun still had to put out more electrons than the green or blue guns and so the red gun trended to poop out sooner than the green or blue guns. |
A Sony' CRTs color is screwed up.
On Jun 2, 12:15*pm, Smarty wrote:
On 6/2/2013 7:23 AM, John-Del wrote: On Saturday, June 1, 2013 4:54:09 PM UTC-4, Smarty wrote: "William Sommerwerck" wrote: Sounds like a purity problem. Start by degaussing it. A purity problem would NOT have black and white looking ok as reported in the original post nor would it result in explicit color replacements as reported. Not true. *Purity problems are most apparent when the chroma is on. *If one looks carefully, the purity problem does exist in the black and white image, but it's just no where near as apparent. Sounds like a color demodulation problem. A color demodulator problem would cause incorrect colors, but I've never seen one cause localized errors as the OP pointed out. Most likely the dual degaussing thermistor is either bad, or has one lead detached from the board. I have not dealt at all with magnetized Trinitrons / aperture grills, and only have very limited experience with magnetized conventional CRTs but purity problems certainly were visible in the black and white images of those needing degaussing. It did not take moving color images to suggest purity / magnetization nor did it take careful inspection. The other, even more confusing original post issue was the non stationary nature of the color shifts, and the fact they were reported as moving with the displayed image, again evidence that the problem was not a purity problem. I gladly defer to the experience and judgement of those who repair TVs. My experience is limited to building a Heathkit color set a million years ago and repairing my Advent and Kloss projectors, not using or needing any purity control whatsoever!- Hide quoted text - - Show quoted text - Hats off to you for building one of those early color tvs. I hated to see Heathkits close up. Do you remember how they started with kits for airplane builders? The electronics came a little later. I still have some instruction manuals for some of their early kits that I built in the 1960s. Had my wife(to be) help me with reading some of the resistor color codes as I am partially RG colorblind |
A Sony' CRTs color is screwed up.
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A Sony' CRTs color is screwed up.
"Phil Allison" wrote in message ... "Smarty" Sounds like a purity problem. Start by degaussing it. A purity problem would NOT have black and white looking ok as reported in the original post nor would it result in explicit color replacements as reported. ** The set is a 19 inch Sony - so it is a Trinitron type. I suspect the behaviour is typical of Triniton with a magnetised aperture grille. The degaussing thermistor may have failed in the set and at the instant of failure left with a parting blow by magnetising the grille. The OP can check for this by noting if the usual switch on " bong" noise still happens. He can also bring a magnet near ( not touching) the screen and see if that tends to fix various areas. Sounds like a color demodulation problem. ** Not likely. ... Phil I agree with Phil. Thinking back, I also seem to recall problems with the Trinitron slot mask becoming detached and causing serious purity problems. I would also dispute that a black and white transmission would not look ok if it was a purity problem. Back in the day, when I was in the TV trade, I saw plenty of examples where you would not have noticed a purity error on a black and white picture unless you knew what you were looking for, but as soon as a colour picture was up on the screen, it was glaringly obvious. Although purity errors *are* visible on a black and white picture, often they appear only as a patch of slightly 'pastel' colouration deviation from the correct grey. My first suspicion would definitely be the degaussing posistor. These commonly cracked and failed at switch on. Arfa |
A Sony' CRTs color is screwed up.
"Phil Allison" wrote in message ... "Smarty" "Phil Allison" "Smarty" ** The set is a 19 inch Sony - so it is a Trinitron type. I suspect the behaviour is typical of Triniton with a magnetised aperture grille. The degaussing thermistor may have failed in the set and at the instant of failure left with a parting blow by magnetising the grille. The OP can check for this by noting if the usual switch on " bong" noise still happens. He can also bring a magnet near ( not touching) the screen and see if that tends to fix various areas. This is altogether surprising to me, but then again I virtually never did TV repair. ** I did - in the B&W days in Australia, circa 1972 and onto to 1976. But it never grabbed me. I have a bit of trouble understanding why a magnetized shadow mask or aperture grill would still allow a black and white image to be correctly displayed. If beam alignment were 'spoiled' by residual magnetic contamination of the CRT near the faceplate or if the purity rings were not doing their job, then the outcome should be color blotches regardless of whether chroma saturation is absent or present. I hope this specific problem is eventually solved so I can hear the actual cause of the problem. This old dog loves to learn new tricks ! ** Once, I was optimistic enough to buy an "re-conditioned" ( = re-gunned ) 26 inch colour tube for my own TV. It was a regular, three stripe, full convergence, colour Toshiba CRT with removable yoke dating from the early 1970s. The tube supplier wanted the old tube back so I had to have it out of the set and ready - the exchange took place around 11AM. I fitted the tube that afternoon and after a heck of a lot of work was able to watch my favourite TV programs the same evening. Doing a full convergence "ab initio" on an aging and rather heavy TV set is not for the faint hearted - but the set served me damn well for another 10 years. Interesting that electron guns cathodes ( particularly the red one ) wear out long before phosphors on the tube face are history. .... Phil Perversely, I actually enjoyed doing a full convergence. I must have changed hundreds of colour tubes over the years that I was in the trade, and on all of the models that we (as a national rental outfit) supplied to our customers, I was able to change a tube from back off to back on and writing up the paperwork, in no more than 40 minutes. Once you had the procedure 'down pat' for a model, it was generally a very straightforward job, although I guess that there was a bit of an 'art' to it. I always found doing a good job of converging a new CRT, was an immensely satisfying feeling ... Arfa |
A Sony' CRTs color is screwed up.
"John-Del" wrote in message ... On Sunday, June 2, 2013 1:15:58 PM UTC-4, Smarty wrote: I have not dealt at all with magnetized Trinitrons / aperture grills, and only have very limited experience with magnetized conventional CRTs but purity problems certainly were visible in the black and white images of those needing degaussing. It did not take moving color images to suggest purity / magnetization nor did it take careful inspection. Perhaps your experience is with the old delta gun arrangement, which were prone to more purity error and more severe error. But I can tell you that with modern in line arrangements (Sony being no exception), bad purity is not always obvious in black and white pictures. +1 - see below The other, even more confusing original post issue was the non stationary nature of the color shifts, and the fact they were reported as moving with the displayed image, again evidence that the problem was not a purity problem. I reread the OP's post several times, and don't see what you mean by non stationary color shift. From what I read, the purity error was static on the screen. I'm not a betting man, but I'd bet that if the OP degausses the TV, the problem will go away. Yes. I couldn't see where he said that it was a shifting problem, either. I have seen shifting purity errors, where the shadowmask has become detached from its frame at one or more of the spot welds. Localised heating from high luminance areas of the picture can then cause the shadowmask to expand non-linearly and distort at the point of detachment, resulting in severe, and non-constant purity errors. On more than one occasion, I have seen a sort of 'strobing' purity error like a kaleidoscope pattern, as a detached shadowmask heats and 'pings' and then cools back and then does it again and so on. As to purity errors being visible on black and white pictures, other than the fact that the the phosphors have different efficiencies, and the drive levels are different for assorted reasons, it doesn't actually matter that much that the phosphors are being excited by the 'wrong' beams. The mix will still make something that approximates to white - or shades of grey - sufficiently well for it not to be glaringly obvious. More a sort of 'dirty patch' on the picture. However, as soon as a colour picture is viewed on the same gaussed up CRT, the error is immediately visible Arfa |
A Sony' CRTs color is screwed up.
I am also saddened to see the era of electronic construction fade away. No doubt the deterioration of American leadership and expertise in "building things" is a bigger and related source of disappointment for those of us who remember this period fondly, and have deep concerns for our kids and grandchildren. The Heathkit appeal for me personally wore out as I began to do my own designs and finished my engineering program. I got heavily into digital, gave up ham radio (except for radioteletype RTTY), and began buying more advanced audio and video stuff. My basement in my parent's home looked like a cross between a wholesale electronics parts supplier and a messy teenager's bedroom......... Take a squint at http://heathkit.com/survey/index.php/278489?lang=en Arfa |
A Sony' CRTs color is screwed up.
What most likely happened here is that that the solder connections to the degaussing thermistor went bad and opened up on the initial surge after turnon.
The idea is to magnetise one way and the other at less and less strength, evenually decaying to zero. What hapens in this failure mode is it gets magnetised one way, the connection breaks and the process is incomplete. Because of the high amperage involved there is usually a brown ring around the connection. To resolder you have to remove the old solder and clean the pin as well as the pad. The other possibility is the shadow mask (aperature grill in a Sony) cut loose. There is no fix for that, though I can do wonders with magnets around the bell of the CRT. The problem with that is that it might not be stable. |
A Sony' CRTs color is screwed up.
I would also dispute that a black and white transmission
would not look ok if it was a purity problem. I've been trying to reason this through. The best I can come up with is this... Whether purity is good or bad, the electron beams have to land /somewhere/. In a B&W image, it might not matter much if red winds up on blue, blue on green, and green on red. The result will be /something/ approximating a shade of gray. |
A Sony' CRTs color is screwed up.
It depends a bit on how well the phosphors' efficiency is matched. If the three cathode currents are pretty close, alot of people won't see much. I know what to look for though, and you need the right material to see it, alot of white. If the picture is too busy it is hard to see. Also, if the actual phosphor efficiency is not well matched, they compensated by making the less efficient phosphors larger.
Also a magnetised CRT will exhibit some misconvergence, which is more visible on a high contrast image. You have to look hard though because the color fringes will not be pure red, green or blue. But yes, in essence those electrons are going to hit somewhere. |
A Sony' CRTs color is screwed up.
On 6/2/2013 9:37 PM, Arfa Daily wrote:
I am also saddened to see the era of electronic construction fade away. No doubt the deterioration of American leadership and expertise in "building things" is a bigger and related source of disappointment for those of us who remember this period fondly, and have deep concerns for our kids and grandchildren. The Heathkit appeal for me personally wore out as I began to do my own designs and finished my engineering program. I got heavily into digital, gave up ham radio (except for radioteletype RTTY), and began buying more advanced audio and video stuff. My basement in my parent's home looked like a cross between a wholesale electronics parts supplier and a messy teenager's bedroom......... Take a squint at http://heathkit.com/survey/index.php/278489?lang=en Arfa Excellent !!!! |
A Sony' CRTs color is screwed up.
On 6/2/2013 11:07 PM, William Sommerwerck wrote:
I would also dispute that a black and white transmission would not look ok if it was a purity problem. I've been trying to reason this through. The best I can come up with is this... Whether purity is good or bad, the electron beams have to land /somewhere/. In a B&W image, it might not matter much if red winds up on blue, blue on green, and green on red. The result will be /something/ approximating a shade of gray. Yes, but, at least conceptually, the relative proportion of the R,G,B components at any (and all) landings either are correct, in which case white (and varying shades of gray) are made, or they are not in the right proportion, and the resulting color is a pastel. I would have guessed that a magnetized and thus misaligned set of landings would not only make green areas appear blue, peripheral areas to appear red, etc. (such as the form of the original complaint) rather than maintain uniform white proportions across the CRT. Here is where my confusion remains, but I simply accept the statements of others here who actually repair tvs that such is indeed not the case. |
A Sony' CRTs color is screwed up.
"William Sommerwerck" wrote in message ... I would also dispute that a black and white transmission would not look ok if it was a purity problem. I've been trying to reason this through. The best I can come up with is this... Whether purity is good or bad, the electron beams have to land /somewhere/. In a B&W image, it might not matter much if red winds up on blue, blue on green, and green on red. The result will be /something/ approximating a shade of gray. Correct, as I explain elsewhere in the thread Arfa |
A Sony' CRTs color is screwed up.
On 6/3/2013 1:07 PM, Arfa Daily wrote:
"William Sommerwerck" wrote in message ... I would also dispute that a black and white transmission would not look ok if it was a purity problem. I've been trying to reason this through. The best I can come up with is this... Whether purity is good or bad, the electron beams have to land /somewhere/. In a B&W image, it might not matter much if red winds up on blue, blue on green, and green on red. The result will be /something/ approximating a shade of gray. Correct, as I explain elsewhere in the thread Arfa Arfa, As a newcomer to this group, I hesitate to be a contrarian or appear to be in any way argumentative or disagreeable. I must admit however that the notion that random or even partial mis-registration of color is somehow magically unimportant because the beam has to land someplace anyway is just totally counter-intuitive and frankly, I believe, wrong. To make the screen appear white or any non-tinted shade of gray, the ratio of red, green, and blue is explicitly defined. As soon as some of the energy intended to light the red phosphor mistakenly lands on the blue, or any other permutation you may want to consider, the ratio is no longer producing a shade of gray. It is certainly obvious when you consider the two extreme limits, one a single RGB triad, the other the entire faceplate of all triads (stripes) that if you mis-direct the energy by, let's say, stray magnetism, that the net effect will be to change the color outcome.Consider these 2 examples: If, for example, in the single triad case, the red beam was landing on green rather than red, causing the green phosphor dot to be disproportionately excited, the color shift would be intuitively to more green. At the opposite limit, for the full faceplate, were the red gun's energy to, somehow, mis-register all of its energy on the green stripes or neighboring triad dots, the same would be true. The resultant color would be lacking in red and oversaturated in green. I use these limit examples as a mental exercise to illustrate my point, and claim / deduce logically that any example you want to choose in between will act in the same manner. If we were talking about power density per square centimeter of energy being delivered to the faceplate, I would share the conclusion of you and William, but we are not talking about average power density. The mis-registration has a consequence when it comes to color purity. My original and continuing opinion remains that black and white does NOT mask the purity imperfections as you and William content, but perhaps this effect is less noticeable because of other considerations (such as human non-linear ability to perceive chromaticity errors around white versus our much better ability to discern shades of flesh tones.) This falls into the murky area of perceptual confusion which allows the brain and our sensors to easily see some things yet somehow ignore others, just as is the case for sound and our other senses as well. I remain fully open to the possibility that black and white does not reveal purity errors to the same degree for this reason alone, but I do not in any way buy the argument that mis-aligned / mis-registered electronics landing on the wrong phosphors is somehow physically unimportant or invisible due to some odd averaging effect acting to compensate or some physical phenomena allowing such arbitrary changes in color proportions to somehow become invisible. |
A Sony' CRTs color is screwed up.
"Smarty" wrote in message ...
As a newcomer to this group, I hesitate to be a contrarian or appear to be in any way argumentative or disagreeable. You didn't hesitate to do it to me. Don't pretend to be "diffident, modest, and shy", because you aren't. I don't have as much experience servicing TVs as others in this group. But I have noticed that impurity is less visible with a monochrome signal than a color one. Clearly, the visibility will vary with all the factors stated, and possibly some we've missed. I can understand your confusion about this point, and it is a point of confusion I share. But I must remind you of what Sherlock Holmes said, that to speculate without data weakens the mind. To argue about what is or is not theoretically visible is a complete waste of time, when a simple experiment would resolve the issue. (And if anyone reading this thinks I will slide the yoke on my 13" Trinitron to see what happens -- they are mistaken.) |
A Sony' CRTs color is screwed up.
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A Sony' CRTs color is screwed up.
On 6/3/2013 5:30 PM, William Sommerwerck wrote:
"Smarty" wrote in message ... As a newcomer to this group, I hesitate to be a contrarian or appear to be in any way argumentative or disagreeable. You didn't hesitate to do it to me. Don't pretend to be "diffident, modest, and shy", because you aren't. I have never claimed to be modest or shy, and those who know me would certainly not categorize me in that manner. As for diffidence, I have a healthy amount of self confidence in what I say based on an excellent education and a vast amount of experience. I do push back when I see a combination of unsupported technical mumbo-jumbo, particularly when it arises from ignorance, arrogance, or a combination of the two. In your case, both attributes are stunningly obvious. And on the subject of obvious, since you are apparently a fan of Sherlock Holmes.... The observation of how a black and white image is perturbed by magnetization can and probably is the cause of your confusion. "There is nothing more deceptive than an obvious fact" said Holmes in The Bascomb Valley Mystery". You, William, are easily deceived, and cannot separate fact from your own technically ignorant notion of how things actually work. |
A Sony' CRTs color is screwed up.
I do push back when I see a combination of unsupported
technical mumbo-jumbo, particularly when it arises from ignorance, arrogance, or a combination of the two. I've been holding off "pushing back" on your generally incorrect views about surround sound. Coming soon to a UseNet group near you... |
A Sony' CRTs color is screwed up.
On Monday, June 3, 2013 5:35:29 PM UTC-4, micky wrote:
Thank you all. I've read all the posts as of last night, and I also like the idea of degaussing and of using a magnet to see what happens. Don't use magnets. There is no reason to try. A strong enough magnet will warp or snap a support in a Trinitron, or at the very least, magnetize one of the mounting brackets which will require repeated degaussing. As far as your salvaged degauss coil, they use AC. In the TV, it's hit with (generally) 85 VAC* and decays rapidly as the thermistors heat. *based on 120VAC input. If you have a variac, wire a plug to the coil and plug it in. Set the variac for 50 to 60 VAC, plug your coil in and wave it around the front of the TV in a circular motion getting within 6" or so, then, continuing the motion, slowly back away from the TV until you get to a few feet away. |
A Sony' CRTs color is screwed up.
On Jun 3, 4:30*pm, "William Sommerwerck"
wrote: "Smarty" *wrote in ... As a newcomer to this group, I hesitate to be a contrarian or appear to be in any way argumentative or disagreeable. You didn't hesitate to do it to me. Don't pretend to be "diffident, modest, and shy", because you aren't. I don't have as much experience servicing TVs as others in this group. But I have noticed that impurity is less visible with a monochrome signal than a color one. Clearly, the visibility will vary with all the factors stated, and possibly some we've missed. I can understand your confusion about this point, and it is a point of confusion I share. But I must remind you of what Sherlock Holmes said, that to speculate without data weakens the mind. To argue about what is or is not theoretically visible is a complete waste of time, when a simple experiment would resolve the issue. (And if anyone reading this thinks I will slide the yoke on my 13" Trinitron to see what happens -- they are mistaken.) There are two things present that have to be understood. There is convergence, which is making sure the 3 electron beams hit the same spot/area at the same time. There is purity, which is making sure the 3 beams hit their respective phosphors. Let us assume that for some reason, all three electron guns come in at an incorrect angle thru the shadow mask or grid or screen. The blue electron gun hits 50% on the blue phosphor and 25% on the red and 25% on the green phosphor. The red gun hits 50% on the red phosphor and 25% on the blue and 25% on the green phosphor. The green gun hits 50% on the green phosphor and 25% on the red and blue phosphors. All three phosphors are illuminated at 100%, so only differing electron beam strengths due to compensating for differing phosphor efficiencies will be noticeable in any color shading of white and gray areas of the picture. Assuing that the convergence of the three images is correct, and only purity is bad, it will take a trained eye to tell that there is a purity problem on a B+W picture. But, as soon as a color picture is presented, colors will be noticeably "off". I taught color TV servicing at an out-of hours course at Bell Laboratories 50 years ago and have kept my hand in repairs ever since. Getting good convergence and purity was/is always a challenge. Taking tv's on a swivel base and maintaining pruity as the set is rotated through 120 degrees was always a challenge. The new flat-screen non-crt tvs are a blessing!!! |
A Sony' CRTs color is screwed up.
On Sun, 2 Jun 2013 11:19:33 +1000, "Phil Allison"
wrote: "Smarty" Sounds like a purity problem. Start by degaussing it. A purity problem would NOT have black and white looking ok as reported in the original post nor would it result in explicit color replacements as reported. ** The set is a 19 inch Sony - so it is a Trinitron type. Yes, Trinitron. I should have said that. Maybe even 25 years old. I got it used. I suspect the behaviour is typical of Triniton with a magnetised aperture grille. The degaussing thermistor may have failed in the set and at the instant of failure left with a parting blow by magnetising the grille. The OP can check for this by noting if the usual switch on " bong" noise still happens. I have heard the bong sound somewhere, but don't remember heearing it with this TV. At any rate, I didn't hear the bong when I turned it on an hour ago, but I wasn't listening for it. I have to go upstairs again. He can also bring a magnet near ( not touching) the screen and see if that tends to fix various areas. No, it didn't. I used a medium sized magnet. 1" by 5/8" by 3/8"thick and parenthesis-shaped. I think it was one of three magnets from a picture tube yoke, I guess a color yoke. It had no effect on black areas and white areas of the screen, but on other areas, it would drag a yellow ring along with it when I held the magnet an inch from the screen and moved it around. Yellow is not a common color on the evening news, so I don't think it fixed anything. Does all this mean it's not the degaussing circuit? I put a listing on Freecycle, but to maximize responses, I said I would "list it again in a week or email the donor". This time I got a nice email saying my heart was in the right place, but I couldn't mention anything hinting at giving it back to the guy who gave it to me. (This is the third time I've tried to borrow something. One of the other two times, the moderator permitted it, and the other time he just refused it, without the compliment and without coaching me on how to get around it. One time was the metal detector (to try to find the corner of my property) and I forget what the other thing was.) Sounds like a color demodulation problem. ** Not likely. ... Phil |
A Sony' CRTs color is screwed up.
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A Sony' CRTs color is screwed up.
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A Sony' CRTs color is screwed up.
wrote in message ... On Jun 3, 4:30 pm, "William Sommerwerck" wrote: "Smarty" wrote in ... As a newcomer to this group, I hesitate to be a contrarian or appear to be in any way argumentative or disagreeable. You didn't hesitate to do it to me. Don't pretend to be "diffident, modest, and shy", because you aren't. I don't have as much experience servicing TVs as others in this group. But I have noticed that impurity is less visible with a monochrome signal than a color one. Clearly, the visibility will vary with all the factors stated, and possibly some we've missed. I can understand your confusion about this point, and it is a point of confusion I share. But I must remind you of what Sherlock Holmes said, that to speculate without data weakens the mind. To argue about what is or is not theoretically visible is a complete waste of time, when a simple experiment would resolve the issue. (And if anyone reading this thinks I will slide the yoke on my 13" Trinitron to see what happens -- they are mistaken.) There are two things present that have to be understood. There is convergence, which is making sure the 3 electron beams hit the same spot/area at the same time. There is purity, which is making sure the 3 beams hit their respective phosphors. Let us assume that for some reason, all three electron guns come in at an incorrect angle thru the shadow mask or grid or screen. The blue electron gun hits 50% on the blue phosphor and 25% on the red and 25% on the green phosphor. The red gun hits 50% on the red phosphor and 25% on the blue and 25% on the green phosphor. The green gun hits 50% on the green phosphor and 25% on the red and blue phosphors. All three phosphors are illuminated at 100%, so only differing electron beam strengths due to compensating for differing phosphor efficiencies will be noticeable in any color shading of white and gray areas of the picture. Assuing that the convergence of the three images is correct, and only purity is bad, it will take a trained eye to tell that there is a purity problem on a B+W picture. But, as soon as a color picture is presented, colors will be noticeably "off". That is 100% correct, and an adept description of how such errors are barely noticeable on a black and white picture. Understand also that we are talking pure CRT physics here. Don't get confused by colour signal weightings that are part of the encoding and transmission process. Whilst there are some differences in the efficiencies of the phosphors, and the eye is non linear in its response to the visible spectrum, those differences are not huge, and for white through shades of grey, the three beam currents will not be wildly different for a CRT that's in good emmissive order. Hence the reason that mass beam landing errors are not anything like as important to the reproduction of an accurate grey, as you might imagine. The fact that such errors are much easier to see on a colour picture may well be a perceptual one, as the human eye / brain combination, is extremely good at handling colour perception. Single beam landing errors - convergence errors - are of course, much easier to see on a black and white picture. As to questioning the credentials of the people that have replied to this, being new, you should probably be aware that the William has a lifetime's experience at the sharp end of service, sales and technical writing, Bob has lectured the stuff, I spent many thousands of hours of my life working on this stuff at nuts and bolts level, and Phil, for all his occasional rants and outbursts, is a highly qualified service engineer whose technical understanding and ability is without question. I don't think that any of us have actually said that purity errors are *not* visible on a black and white picture - they are - but we have all agreed, based on a collective several lifetimes actually working on this stuff professionally, that they are nothing like as obvious as they are on a colour picture, and that someone who is not as well versed in the subject, may have difficulty seeing such errors under those circumstances, or identifying exactly what the problem was if they could see them. Whilst I'm sure that very severe purity errors concentrated in a small area - such as you used to get when little Johnny helpfully waved a magnet at the tube face - might show rather more than a 'general' large area purity error, the fact remains that typical large area errors caused by failure of the auto degaussing circuit, or turning the set whilst it is on, manifest on a black and white picture as typically a pastel coloured 'stain' or an area that looks 'dirty'. I can't really think of a better description than those. Arfa I taught color TV servicing at an out-of hours course at Bell Laboratories 50 years ago and have kept my hand in repairs ever since. Getting good convergence and purity was/is always a challenge. Taking tv's on a swivel base and maintaining pruity as the set is rotated through 120 degrees was always a challenge. The new flat-screen non-crt tvs are a blessing!!! |
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