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(7) Purity Adjustment
1)
Be sure that the display is not being exposed to any external magnetic fields.
2)
Ensure that the spacing between the Purity, Convergence Magnet, (PCM)' assembly and the CRT
stem is 29 mm±1 mm. (See below diagram)
3)
Produce a complete, red pattern on the display. Adjust the Purity magnet rings on the PCM
assembly to obtain a complete field of the color red. This is done by moving the two tabs in such
a manner that they advance in an opposite direction but at the same time to obtain the same angle
between the two tabs, which should be approximately 180
0
•
4)
Check the complete blue and compiete green patterns to observe their respective color purity. Make
minor adjustments if needed.
Purity Magnets
4'pole magnets (Red to Blue Convergence)
6-pole magnets (Green to Magenta Convergence)
29'±1 mm
Purity, Convergence Magnet Assembly (PCM)
B R
Perform the adjustment by opening
the angle between the tabs.
~
I
B----i
R---r-i--y--
Perform the adjustment by synchronous
rota tion of the two tabs.
B/RG
.
.
I
Perform the adjustment by opening
the angle between the tabs.
B/R
I
---i--I-....L-- G
I
Perform the adjustment by synchronous
I
rotation of the two tabs.
Red to Blue Convergence
(Magenta)
Green to Magenta Convergence
(White)
(8) Convergence Adjustment
1)
Produce a magenta crosshatch on the display.
2)
Adjust the focus for the best overall focus on the display.
Also adjust the brightness to the desired condition.
3)
Vertical red and blue lines are converged by varying the angle between the two tabs of the 4-pole
magnets on the PCM assembly. (See above diagrams)
4)
Horizontal red and blue lines are converged by varying the two tabs together, keeping the angle
between them constant.
5)
Produce a white crosshatch pattern on the display.
6)
Vertical green and magenta lines are converged by varying the angle between the two tabs of the
6-pole magnets.
7)
Horizontal green and magenta lines are converged by varying the two tabs together, keeping the
angle between them constant.
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