Background Luminance Adjustment; Focus Adjustment; Purity Adjustment - Tatung OMNISCAN SERIES Service Manual

2.10 Contrast Tracking 2
A. Apply signal 89 (64KHz), full white pattern.
B. Initial Settings of Adjustment VRs.
R721: Contrast VR Adjust to obtain 3FL.
R722: Brightness VR MIO'POINT
C. Adjust G GAIN 2 VR (R081) and B GAIN 2 VR
(R141).
D. Measure the color temperature X and Y.
X = 281 (+ /- 5)
Y = 311 (+/- 5)
E. Check the color temperature X and Y between
the following condition:
X=281 (+/-15)
Y=311 (+/-15)
(1) Brightness MID'POINT., Contrast MAX.
(2) Brightness MID'POINT., Contrast
Adjust to obtain > 5 FL
2.11 Background Luminance Adjustment
A. Initial setting of the adjustment VRs.
R722:
R721 :
Brightness VR
Contrast VR
MID'POINT
MIN.
B. Apply sign'al 89 (64KHz), crosshatch pattern.
C. Adjust SCREEN VR so that the background just
disappear.
2.12 Focus Adjustment
(1) Single Focus (TOSHIBA Tube)
A. Apply signal 89 (64KHz), crosshatch pattern.
B. Initial setting of the adjustment VRs.
R722:
R721:
Brightness VR
Contrast VR
MID'POINT
MAX.
C, Or receive the pattern with "e" character.
D. Adjust the FBT focus VR to achieve the best
focus at an intermediated point between the
center of the screen and the corner.
r -
~
I-
Best
focused
~
1'""
t ./
(2) Double Focus (NEC/HITACHI Tube)
A. Apply signal 89 (64KHz), crosshatch pattern.
B. Initial setting of the adjustment VRs.
R722:
R721:
Brightness VR
Contrast VR
MIO'POINT
MAX.
C. Or receive the pattern with "e" character.
D. Focus 1:
Should be adjusted so that the vertical lines
become narrowest in all over the screen.
E. Focus 2:
Should be adjusted so that the horizontal lines
become narrowest in all over the screen.
F. Repeat the adjustment procedure in step 0 & E
until the vertical and horizontal lines are all clear
at center and corner of screen.
0
Best focused
v-.
-
I'-'
-
2.13 Purity Adjustment
A. Be sure the display is not being exposed to any
external magnetic fields.
B. Ensure that the spacing between the Purity
Convergence Magnet (PCM) assembly and the
CRT stem is 29mm (+/-1mm).
C. Produce a complete red pattern on the screen.
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2-5
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