[time-nuts] [OT] degaussing
max at maxsmusicplace.com
Sat Apr 17 22:09:00 EDT 2010
I haven't been following this thread but here are my comments based on the
attached messages. You may have difficulty finding a service technician who
knows how to adjust purity and convergence on a CRT. In about 1975 they
started coming from the factory with deflection yokes installed and all
purity and convergence adjusted.
Max. K 4 O D S.
Email: max at maxsmusicplace.com
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----- Original Message -----
From: "Arnold Tibus" <Arnold.Tibus at gmx.de>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Saturday, April 17, 2010 7:04 AM
Subject: Re: [time-nuts] [OT] degaussing
> The dotpitch of Trinitron and Diamondtron tubes (Mitsubishi)
> is at 1/100 inch (0.24 mm to 0.27 mm), which defines the distance
> of these shadow wires. What tube width do you have? ;-)
> The wires are very sensitive to vibrations which makes the horizontal
> stabilizing wires necessary (in most cases 2, max. 3). These are visible
> with a bright and uniform picture.
> All such tubes are equipped with a degaussing system
> (electromagnetic coil in a black hose) which are normally activated
> always when switching the monitor/ TV on. There is normally no
> forther degaussing needed.
> One can apply stronger magnetic fields from the front side by using
> cannibalized coils in parallel with an adequate 50/ 60 Hz system
> stepping the field continuously down. Attention, strong dc H- fields
> may result in sticking some wires together, which may be very
> difficult to get it corrected!
> The small magnets on the back of the tube are necessary to
> linearize the dynamic field of the deflecting coil and to compensate
> other small steady magnetic distortions around the tube.
> There are some more magnets on the neck of the tube for
> convergence and beam forming.
> A long and distracting work to to when you had to replace the tube
> or coils and then to adjust for white and clean colors and sharp
> Older systems needed an earth field compensation in situ.
> (Don't try it when you are not experienced with it, you will turn crazy -
> and the professional serviceman later will as well!)
> On Fri, 16 Apr 2010 21:05:31 EDT, SAIDJACK at aol.com wrote:
>>point of trivia:
>>can you count how many vertical wires are strung across a Trinitron
>>monitors' shadow mask??
>>I used to work at Sony for a long time, we had a TV assembly line next
>>If you can see the vertical wires, you still have very good eyesight...
>>In a message dated 4/16/2010 04:55:35 Pacific Daylight Time,
>>cfharris at erols.com writes:
>>Are they really? For some reason, every Trinitron I have ever seen
>>has clusters of little stick on magnets placed here and there on the
>>back of the glass envelope.
>>The trinitron has a shadowmask. It is a grill of highly tensioned wires
>>that are positioned just behind the screen. The original trinitron tube
>>was a little 5 inch diagonal CRT. It had to be small because the wires
>>tended to vibrate if the set was bumped, and that made for some very odd
>>displays. The later larger tubes had horizontal titanium wires welded to
>>the backs of the shadow mask wires every 5 or 10 inches, to prevent the
>>psychedelic color fest that happened when the CRT got bumped.
>>The trinitron has three very carefully aligned cathodes in the gun. They
>>are positioned side-by-side, creating the slight different projection
>>angles necessary to cause the long vertical slots formed by the shadow
>>to eclipse the appropriate color bands on the screen.
>>I'm not sure what you are describing; it sure sounds cool; but it isn't
>>Can you find some references? I'd like to read up on it.
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