Hitachi C43-FD8000, Service Manual

Page: 39 / 250

39
SERVICE ADJUSTMENTS
2.10 BEAM FORM ADJUSTMENT
Preparation for adjustment
(1) The beam alignment should be completed.
(2) The raster tilt, centering, horizontal and vertical size adjustments should
be completed. Optical focus should be coarsely adjusted.
(3) PICTURE control should be set the Factory Preset condition.
(contrast : max , other items : center)
(4) Input the dot signal.
(5) Aspect : 4:3 standard mode(16:9 Model only).
Adjustment procedure
(1) Green PRT beam shape adjustment
Short-circuit 2P sub-mini connectors on Red and Blue CPT P.W.Bs. to
project only the green beam.
(2) Turn the green static VR*
1
fully clockwise.
Note : Blooming
(3) Using the 4-pole magnet as shown below, modify the dot pattern of the screen
center to make it to a perfect circle.
(4) Repeat the procedure for the Red*
2
and Blue*
3
PRT beam shapes.
(5) After the adjustment is completed, return R, G and B static VRs to the best focus point.
(6) After the beam alignment is completed, fix the beam alignment magnet with white paint.
*1
*2 Static Focus VR is on FOCUS PACK UFPK
*3
True circle specification
：
4-pole beam shape
correction magnet
2-pole beam alignment
magnet
PRT E. gun side
PRT surface side
a
b
True circle Form Ratio: a/b
Specification: 0.9~1.1