Tatung VM9AF, Service Manual

Page: 8 / 27

- 8 -
4-7 Vertical height adjustment
(a)
test pattern: cross hatch
(b) set up external brightness and contrast VR to central position.
(c) Adjust VR302 to make height to 120±4 mm.
4-8
Vertical-hold (Free-run 52Hz) adjustment:
(a)
disconnect video signal
(b) use frequency counter
⊕
leader, measure vertical yoke point,
adjustment VR303 make frequency value to 52Hz.
4-9 Raster
adjustment:
(a) disconnect video signal
(b) set up external brightness VR to maximum, external contrast VR to
maximum.
(c) Adjust VR403 to have luminance equal to 0.5 ~ 1.0 FL.
4-10 Brightness
check:
(a) test pattern: full white
(b) set up external brightness and contrast VR to maximum position
(c) over 60 FL.
4-11 Focus
adjustment:
(a) test pattern: “H” character pattern
(b) set up external brightness and contrast VR to central position
(c) adjust VR404 have central picture and 4 corners to be distinguished.