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From: bl@hplabsb.UUCP (Bruce T. Lowerre)
Newsgroups: net.video
Subject: Re: Magnetic fields and Color TV Warning/Questions
Message-ID: <3249@hplabsb.UUCP>
Date: Fri, 31-Jan-86 14:47:06 EST
Article-I.D.: hplabsb.3249
Posted: Fri Jan 31 14:47:06 1986
Date-Received: Sat, 1-Feb-86 20:49:14 EST
References: <499@oliven.UUCP>
Organization: Hewlett Packard Labs, Palo Alto CA
Lines: 37

...
> There are two things I don't understand:
> 
> 1) Why did the problem remain for so long (15 minutes) after the speakers
> were moved (far away) from the set?  Is the picture tube capable of holding
> a magnetic charge?  Is there metal sheilding around the tube which could
> hold a magnetic charge?  Could this permanently damage the picture tube?

yes, yes, yes.

> 2) Why did the magnetic field cause the distinct red, blue, and green
> zones to appear?

Because it's a color TV (this sounds facetious, but true).

> Is there a relationship between color (frequency ?) and the amount of
> deflection from the magnetic field?

No, the same electron guns are used for all three colors.

> Is it related to the distance of the gun(s) or lens(es) from the magnetic
> field?

No.
 
> Excuse the dumb questions, but physics was a long time ago and I am
> fairly ignorant of the inner workings of a color television set.
> Recommendations of good books on the subject would be appreciated.
> 
...
> Any ideas or commments out there?

You didn't ask the really good question.  "Why did the problem clear up
when you shut off your TV and then turned it back on?"

Answer:  The set probably has a built-in de-gaussing coil which is active
only during warm-up.  You lucked out in that the set was able to fix itself.