Crt Screen And Faceplate Blemish Limits; Crt Face Plate Defect - Mitsubishi DPLUS 74SB -BKA Service Manual

6. CRT Screen and Faceplate Blemish Limits

6.1 CRT Face Plate Defect

6.1.1 Inspection Condition
(1) In the operating condition, observe the defect on the screen under following condition.
9,300K (x=0.283, y=0.297) white raster or the element monochrome raster which its brightness is
2
34cd/m (10ft⋅L) on the screen center surrounding light is about 10 Lux.
(2) In the non-operating condition, observe the defect of the screen under light of about 200 Lux, measured
at the faceplate.
(3) Inspection shall be made more than 45 cm away from the screen.
(4) Observe the screen on white raster and each monochrome color of red, green and blue.
6.1.2 Division of Zone
A screen is divided into following 2 zones.
zone A : Area inside the rectangle that its size measures the followings in the center of screen.
H : 300 mm, V : 225 mm
zone B : Area outside the above rectangle
6.1.3 Limits
(1) CRT face defect
(a) Distance (minimum distance )
(b) Average diameter
+
a b
Turn of
2
(c) Limit
* Dark spot, Blocked aperture
Average diameter (mm)
0.51 ~
0.31 ~ 0.50
0.15 ~ 0.30
* Discoloration, stain, Missing phosphor, etc.
Average diameter (mm)
0.51 ~ 0.75
0.15 ~ 0.50
Note 1 : No missing spot larger than specified are allowed in Zone A.
Note 2 : The spec applies to each color.
(a: length, b: width)
A
0
0
6 (note 1) 6 (note 1) 10 (note 1)
A
0
2
a
b
b
B A + B minimum distance
0 0
0 0
B A + B minimum distance
1 -
3 -
5-23
-
-
10 mm
20 mm
20 mm