NEC VT440 Service Manual page 73

METHOD OF ADJUSTMENTS
Picture Quality Decision Criteria
Judge units that satisfy the following criteria as acceptable.
(1) Pixel Mis-Convergence
The pixel Mis-Convergence of the red and blue shall be as specified below in reference to the green.
• 1 pixel or less in the center area
• 1 pixel or less in the peripheral (Edge) areas
Mis-Convergence of one quarter (1/4) or more from the above specifications (1 1/4 pixels in the peripheral
area) may be acceptable, provided that the signal color of green registers with the pixels of the other colors and
does not appear seriously poor as viewed 2 meters away.
(2) A bright pixel defect is always visible on a totally black screen in units of pixels.
Up to 6 pixel defects are permissible for a single color, or up to 18 pixel defects for all the three colors combined.
Bright spots of less than 1 pixel are acceptable unless they are frequently visible 2 meters away.
(This does not apply to bright spots concentrated or markedly visible.)
(3) Dust, smear
Any dust or smear visible in excess of 2 pixels is not permissible at the best focus point.
(2) Replace the LCD panel if bright spot defects exceed the specified level.
(3) Remove dirt and smear in excess of the permissible level.
Lens and Mirror Cleaning
(1) Lens Cleaner
* Cleaning fluid
Use absolute alcohol.
If moisture remains on the surface without drying soon after it is cleaned, use
fresh absolute alcohol.
* Cleaning method
Soak a clean cotton cloth or a sheet of commercial cleaning paper with the
cleaning fluid. Hold it between your thumb and index finger, and start cleaning
the lens at the center and circle the cloth or paper toward the edge, wiping off
foreign matter out to the edge. Do not apply pressure on the lens surfaces
while cleaning.
(2) Mirror Cleaner
Never grip the mirror hard because it is vapor-deposited. Minor stains may be removed by dissolving them with
alcohol and wiping off dry.
(3) Point
Stains on both sides of the LCD unit and on the LCD side of the field lens degrade the picture. Keep them
clean.
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