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Old 4th December 2003, 08:00 PM   #1
ewan is offline ewan  United Kingdom
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Join Date: Dec 2003
Location: Edinburgh, Scotland
Default Would this require degaussing?

Sorry to turn this into a consumer advice forum but I could do with some advice.

I've just returned a TV to the shop 6 months after purchasing it because it stopped being a colour TV and became a black and white TV overnight...

The store manager, trying to get rid of me I think, told me that it might just need degaussing and they'd look into it. I'm dubious about this 'cos the only time I've seen a screen affected by a magnetic field before it appeared as a 'patch' of colour round the edge of the screen rather than affecting the whole thing. Also, this telly wasn't anywhere near a speaker or anything else, and I can't imagine that it would just 'lose' all the colour even if this was the case. I reckon that there's some other problem and I don't really want the TV back at this stage.

However, I don't really know what I'm talking about so any advice on whether he's just giving me a spiel would be appreciated.

Thanks folks,
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Old 4th December 2003, 11:42 PM   #2
diyAudio Member
Join Date: Sep 2002
Location: Sweden
Well it is late and I ought to go to bed and thus may be
confused, but how on earth could magnetic fields make the
colour go away. It can distort the picture in various ways,
possibley even affecting different colours differently, but the
colour will still be where. There is are no black or white
phospors on the screen, so all colours have to be there to
get white at all.
Seems to me they are trying to BS you or don't have a clue
about what the problem is and won't admit it.

BTW some computer monitors, like my Sony, degauss
automatically on startup, but that is definitely not in order
to prevent the colours from vanishing. I am no expert on
TVs, but it sound like the colour info is lost somewhere along
the path so only the intesity indformation goeas through all
the way. Electronic problem, that is.

Or maybe you have forgotten to refill it with paint?

I had a TV that occasionally turned black and white, but it
was close to 30 years old and I had inherited it from my
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Old 5th December 2003, 02:20 AM   #3
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What he said. Maybe the color control knob is fuzzy...
Seven Transistor Labs, LLC
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Old 5th December 2003, 06:57 AM   #4
dhaen is offline dhaen  Europe
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Location: U.K.
Hi Ewan,

It is most likely BS from the dealer. However it is possible for a CRT to become so magnetised that the beam landing is almost completely random. Then you get a "dirty" looking B&W image. This can be caused by faulty degauss circuitry.
Anyway, whether it's that or not, it's an equipment fault that you have, and the dealer should fix it.
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Old 5th December 2003, 10:59 AM   #5
ewan is offline ewan  United Kingdom
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Join Date: Dec 2003
Location: Edinburgh, Scotland
Thanks folks. V. useful.

That gives me some ammunition for when I go back to the store.

Much Appreciated
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