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[CRT Circuit]
7. Ellipticity
Adjustment To correct distorted light projected from CRT.
purpose
Symptom when
Poor focus of picture.
incorrectly adjusted
Measuring
Instrument
Test Point
Note :
This adjustment shall be performed only after replacing the Green CRT.
*
Cover the Red and Blue CRTs with Lens caps when performing this
adjustment.
1. Supply a dot signal (No.39).
Extemal Trigger
-----
2.
Adjust G (Green) on the Focus controls of VR-FOCUS so that the luminescent
Measurement _____
spot is in the blooming condition to some extent.
1---R_a_n-=g'-e--+---------1! Note :
VR-FOCUS is installed at lhe left bottom of lhe
screen
observing from lhe front.
3. Confirm if the luminescent spot is round. If not round, perform adjustments so
Input Signal
VG-814 (No.39)
Dot
that it will be round as the guidelines below :
Input Terminal Mini D-SUB 15 Pin Input Terminal
[Judgement of Ellipticity]
Perform adjustments to satisfy
CD
and
@
below at the same time.
CD
Ellipticity in Blooming.
b/a
!1;
0.9
® Regard the luminescent spot as ellipse and judge the ellipse direction.
eEl
Open
2
sheets of 4-Pole Magnets on the Focus Magnet at 90°
(Maximum magnetism).
©
Rotate the 4-Pole Magnet while retaining the condition in step
eEl
to
rotate ellipse shown in step® by 90° . (Refer to A in the chart below.)
@
Make catches for 2 sheets of 4-Pole Magnet approach equally (The
polarized amount will decrease) to make the ellipse round.
(Refer to B in the chart below.)
®
Regard lhe luminescent spot
as
triangular circle and judge lhe vertex direction.
CD
Open the 6-Pole Magnet on 2 sheets of the Focus Magnet at 60
o
(Maximum magnetism).
@
Rotate the 6-Pole Magnet while retaining the condition in step
CD
so that
the triangular circle in step e is seen
to
rotate by 180° .
(Refer to C shown in the chart below.)
Clj)
Make catches for
2
sheets of 6-Pole Magnets approach (The magnetism
amount will decrease) so that the triangular circle is seen to be most
round. (Refer to D in the chart below.)
CD
Repeat the steps ®to
C@,
if necessary.
4. Confirm that the position of the picture is correct. If not, readjust the position
with a Centering Magnet on the Deflection Yoke.
5.
After adjustment, lock the Centering Magnet, 4-Pole Magnet, 6-Pole Magnet,
and Alignment Magnet with paint.
6. Remove the Lens cap covering the CRT.
Dot Beam Movement
by
4-Pole Magnet
I
6-Pole Magnet
[Ellipticity Adjustments]
Luminescent Spot
~
b=Longer Diameter
f-o-1
Q
I
a= Shorter
Diameter
Shorter Diameter Direction
0
The round shape of the Halo and Blooming
is the same Blooming
Just
Focus
Halo
OK0--0-®
NGo-o-(2)
A
B
c
D
Movement of Magnet
Rotation
@-.~
of 4-Pole
Magnet
Big angle
@-.f~
in the
opening
of 4-Pole
Magnet
Rotation
@ ..
~
of 6-Pole
Magnet
Big angle
@-.r~
in the
opening
of 6-Pole
Magnet
-23-
Brightness of
Luminescent Spot
Correction of
rotation
·o~-..
-,
position of
0
the
-
,.__
luminescent
_,
spot.
0~
g
Correction
of the
sha~e
of
t e
O~c=D
luminesce
nt spot.
~
~.orrection
ot
the rotation
0
__..
position of
the
,.__
luminescent
spot.
Correction
a
of the
0
__..
sha~e
of
,.__
t e
luminesce
-nt spot.
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