Tatung VM5ERDA Service Manual page 9

D. Full white luminance:
(a) Set mode 4 ( 800×600 Fh: 53.7K ) full white pattern.
(b) Image size : H:260±4mm, V:195±4mm.
(c) Brightness set to raster just cut off and set the contrast to max.
(d) Adjust VR701 to make sure white luminance at 100 ± 2cd/m².
4. Focus adjustment:
A. Set mode 2 ( 640×480 Fh: 31.5KHz ) with character full page.
B. Adjust external brightness to raster cutoff and external contrast to max. , then adjust focus VR to make the
display be focused very well.
5. Purity adjustment
A. Be sure that 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
29• .(See below diagram)
C. 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.
D. Check the complete blue and complete green patterns to observe their respective color purity. make minor
adjustments if needed.
RELATIVE PLACEMENT OF TYPICAL COMPONENTS
6. Convergence adjustment
A. Produce a magenta crosshatch on the display.
B. Adjust the focus for the best overall focus on the display.
Also adjust the brightness to the desired condition.
C. 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)
D. Horizontal red and blue lines are converged by varying the two tabs together, keeping the angle between them
constant.
E. Produce a white crosshatch pattern on the display.
F. Vertical green and magenta lines are converged by varying the angle between the two tabs of the 6-pole magnets.
G. Horizontal green and magenta lines are converged by varying the two tabs together, keeping the angle between
them constant.
Purity Magnets
6-pole Convergence Magnets
4-pole Convergence Magnets
Deflection Yoke