A Sony' CRTs color is screwed up.

Sounds like a purity problem. Start by degaussing it.

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 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.

"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.

** Not likely.

... Phil

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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.

This is altogether surprising to me, but then again I virtually never did TV repair. 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 !

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.

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.

"Smarty" "Phil Allison"

** I did - in the B&W days in Australia, circa 1972 and onto to 1976.

But it never grabbed me.

** 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

looks carefully, the purity problem does exist in the black and white image, but it's just no where near as apparent.

one cause localized errors as the OP pointed out.

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!

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".

Perhaps your experience is with the old delta gun arrangement, which were p rone to more purity error and more severe error. But I can tell you that w ith modern in line arrangements (Sony being no exception), bad purity is n ot always obvious in black and white pictures.

The

I reread the OP's post several times, and don't see what you mean by non st ationary 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 T V, the problem will go away.

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.

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.

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.

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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.

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s  If one looks carefully, the purity problem does exist in the black and w hite image, but it's just no where near as apparent.

r seen one cause localized errors as the OP pointed out.

ad detached from the board.

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

looks carefully, the purity problem does exist in the black and white image, but it's just no where near as apparent.

seen one cause localized errors as the OP pointed out.

detached from the board.

I do remember the original catalogs showing airplane related kits, but I did not get into it really until the late 1950s. I guess I became a Heathkit maniac. I built nearly 50 kits starting in the 1950s and ending in the 70s as I recall. The ham radio stuff was the earliest (DX20, DX40, Apache, SB-1 Single Sideband Adapter, SB101 transceiver, SB200 kilowatt amplifier, Q multiplier, KW Compact mobile amplifier, SWR bridges, wattmeter, phone patch, two meter and UHF rigs,......), test equipment (scopes, signal generators, a couple VTVMs, a couple digital VOM / DMM meters / frequency counter, decade capacitor and resistor boxes,), all sorts of tube and then solid state audio equipment, a

25inch color TV (for my parents), lots of electronic gadgets like digital clocks, indoor outdoor thermometer, digital platform scale, grid dip meter, "Cantenna", weather stations, and on and on.

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.........

Very little of it came with me when I got married and moved out. I presume my parents must have given most of it away except for the very few things I took with me. I still have one remaining Heath item only, an indoor outdoor digital thermometer, which I wound up modifying to control my hot tub water temperature nearly 30 years later!

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.

degaussing thermistor went bad and opened up on the initial surge after turnon.

evenually decaying to zero. What hapens in this failure mode is it gets magnetised one way, the connection breaks and the process is incomplete.

connection. To resolder you have to remove the old solder and clean the pin as well as the pad.

Sounds good. Because this involves turning the tv around (which involves cleaning off the kitchen table) I'm saving this one for third, even though it sounds like something I can do.

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.

Right now, I'm trying to remember where I keep all my magnets. I have all sizes but the only ones whose whereabouts I know are on the refrigerator.

The only degaussing coil I have came from a tv I destroyed. I never found a power supply for it, and right now I also can't remember where it is. There are only two rooms in the basement. It has to be in one of them. But anyhow, I went on Freecycle to try to borrow a degausser. It worked when I needed a metal detector, although it seems borrowing is against the rules, and some moderators won't approve a request to borrow. So I say it's a request to be given and then I'll reccycle it again in a week, including to the original owner. .

There may well have been a current surge while I was gone (though nothing else looks bad, so far, and all the clocks were still right (Yeah, that's not a surge, but still.)

But I don't think there was an earthquake**, so I'm figuring the aperture grill is still in the right place. When I get to the point of moving the tv, I'll turn the screen a little and see if that has a big effect. **We've only had one in 30 years here (Baltimore) and it was not much. However sitting in the basement at the work bench I could feel it, so I do get to cross earthquake off my bucket list.

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.

Without a vow, I'll get back with results when I have them.