Mitsubishi DPLUS 74SB -BKA Service Manual page 88

6.2.2 Division of Zone
A screen is divided into following 3 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 zone A and inside the fluorescent surface edge.
zone C : Area outside the fluorescent surface edge.
225mm
H
6.2.3 Limits
(1) Scratch
Width (mm)
0.16 ~
0.11 ~ 0.15
0.06 ~ 0.10
~ 0.05
NOTE 1 : Even though width of scratch is more than 0.16mm, regard scratch whose contrast is weak
extremely as stain and apply standard of 6.2.3(2).
NOTE 2 : Do not recognize flaws which injures goods prices though it is not especially stipulated as for
zone C.
(2) Opaque flaws (ex. Stain) and coating peeling
Do not apply the following standard to zone C.
Classify flaws by contrast and judge it by size every the contrast.
Definition of a contrast
High contrast :
Middle contrast : A semitransparent foreign substance and stain.
Low contrast :
Note : Ignore the light spot with no interference color.
(However, Non of them with its size in excess of 3.75 mm is acceptable, that damages the product
quality.)
zone A
300mm
V
Allowable Length (mm)(Zone A + Zone B)
The foreign substance which shuts off light from fluorescence surface.
(ex. coating material which has been changed )
stain and dust which do not reflect light from fluorescence surface and can be
distinguished by its appearance.
fluorescent surface edge
zone B
zone C
reject
13
26
unlimited
5-25