A Sony' CRTs color is screwed up.

[micky]

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.

 

[William Sommerwerck]

Sounds like a purity problem. Start by degaussing it.

 

[Cydrome Leader]

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.

 

[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.

Sounds like a color demodulation problem.

 

[Phil Allison]

"Smarty"

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

 

[[email protected]]

"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

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.

 

[Smarty]

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 !

 

[John-Del]

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.

 

[Phil Allison]

"Smarty"
"Phil Allison"

"Smarty"


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

 

[Smarty]

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.

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!

 

[Smarty]

"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.

 

[William Sommerwerck]

"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".

 

[John-Del]

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 thescreen. I'm not a betting man, but I'd bet that if the OP degausses the TV, the problem will go away.

 

[Smarty]

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

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.

 

[[email protected]]

"Smarty"  wrote in messagenews:[email protected]...

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.

 

[[email protected]]

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

 

[Smarty]

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

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!

 

[[email protected]]

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.

 

[William Sommerwerck]

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.

 

[[email protected]]

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, alotof 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 colorfringes will not be pure red, green or blue.

But yes, in essence those electrons are going to hit somewhere.