Hi,
Up to the Philips 20AX tubes they used adjustable multipole units
around the neck of the tube. These multipoles can be readjusted if
needed. From the 30AX design on, the used multipoles that were
internal, thus inside the neck. The required correction was measured
during manufacture and the internal multipole magnetized. Turning the
tube upside down will help down under if the tube was manufactured in
the northern hemisphere. Then tune the deflection yoke back or swap
line and frame connections.
Henk
Op 18 apr 2010, om 04:09 heeft Max Robinson het volgende geschreven:
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.
Regards.
Max. K 4 O D S.
Email: m...@maxsmusicplace.com
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----- Original Message ----- From: "Arnold Tibus"
<arnold.ti...@gmx.de>
To: "Discussion of precise time and frequency measurement" <time-nuts@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
picture...%-))
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!)
greetings,
Arnold
On Fri, 16 Apr 2010 21:05:31 EDT, saidj...@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 door
:)
If you can see the vertical wires, you still have very good
eyesight...
bye,
Said
In a message dated 4/16/2010 04:55:35 Pacific Daylight Time,
cfhar...@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 mask
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
a trinitron.
Can you find some references? I'd like to read up on it.
-Chuck Harris
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