Changhong Electric 21NF55, Руководство по обслуживанию, Страница: 7 / 83

SERVICE MANUAL
5
ADJUSTMENTS
SET-UP ADJUSTMENTS
The following adjustments should be made when a complete realignment is required or a new picture
tube is installed.
Perform the adjustments in the following order:
1. Color purity
2. Convergence
3. White balance
Notes:
①
The purity/convergence magnet assembly and rubber wedges need mechanical positioning.
②
For some picture tubes, purity/ convergence adjustments are not required.
1. Color Purity Adjustment
Preparation:
Before starting this adjustment, adjust the vertical sync, horizontal sync, vertical amplitude and
focus.
1.1 Face the TV set north or south.
1.2 Connect the power plug into the wall outlet and turn on the main power switch of the TV set.
1.3 Operate the TV for at least 15 minutes.
1.4 Degauss the TV set using a specific degaussing coil.
1.5 Set the brightness and contrast to maximum.
1.6 Counter clockwise rotate the R/B low brightness potentiometers to the end and rotate the green low
brightness potentiometer to center.
1.7 Receive green raster pattern signals.
1.8 Loosen the clamp screw holding the deflection yoke assembly and slide it forward or backward to
display a vertical green zone on the screen. Rotate and spread the tabs of the purity magnet
around the neck of the CRT until the green zone is located vertically at the center of the screen.
1.9 Slowly move the deflection yoke assembly forward or backward until a uniform green screen is
obtained.
1.10 Tighten the clamp screw of the assembly temporarily. Check purity o f the red raster and blue raster
until purities of the three rasters meet the requirement.