LG PB60G Service Manual page 7

4.3. Lighting System Margin Inspection
Method and Spec.
- Apply for the sample that the decision for good/fail is difficult
during visual inspection of lighting margin.
(1) Prepare CL-200 with measurement surface of width
20mm, length 5mm as in (Fig. 4-3-1)
(Fig. 4-3-1) CL-200 for lighting margin inspection (right side)
(2) Bring up Full White pattern and check whether Light Cyan
shows.
(Fig. 4-3-2) CL-200 for lighting margin inspection (right side)
(3) Measure the brightness at the boundary of the screen.
(Refer to Fig. 4-3-3)
(Fig. 4-3-3) Measure brightness of screen boundary
(4) Measure brightness at 10mm in the inner direction from
screen boundary. (Refer to Fig. 4-3-4)
(Fig. 4-3-4) Measure brightness at 10mm inside the screen
(5) Lighting Margin Spec shall be smaller than 104% of (4)
brightness/(3)brightness.
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4.4. Focus test method and subject
- Test pattern : Resolution Pattern , White Cross-Hatch
Pattern
- Tools : Focus width measurement ruler
4.4.1. Focus adjustment method
(1) Set the projection distance of Engine as 1200 mm (40 Inch
screen).
(2) Pop up the Resolution Pattern among the Test Patterns of
Set, and fix the Focus on the part where the
Resolution Pattern is classified on each part of screen. (all
parts Balancing)
(3) Popup the White Cross-Hatch Pattern and measure the
width of each Point.
(4) Focus judging standard : 3.5 mm or less (Measure line
width excluding light Flare: Refer to Fig. 4-4-1)
Red Line ( light Flare), Blue Line ( Thick Flare)
(Fig. 4-4-1) Standard for deciding line width
(Fig. 4-4-2) Resolution Pattern
4.4.2. Focus Stopper Location Verification
(1) Test pattern : White cross-hatch
(2) Visually verify focus after locating a white board 594 mm
from the projection lens so that screen is set to 20 inches.
(3) Inspect the location of the stopper after locating a white
board 1210 mm from the projection lens so that screen is
set to 40 inches
(4) Evaluation criteria for stopper location
Non-defective : Bushing shall be located within A marking.
(Fig. 4-3-3)
(Fig. 4-4-3) Bushing verification location
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