Preliminary Adjustment - HP 98770 CE Handbook

98770 Adjustments
6-3
Preliminary Adjustment
Use this adjustment procedure when adjusting a badly misaligned unit, or one in which the
CRT /Y oke assembly has been replaced.
Procedure
1. Set the switch on the A13 (A33. A53. A54) assembly to its forward (red raster) position.
2. Turn the high voltage control (A44) fully CCW for the maximum high voltage
3. Adjust the brightness controi (under iower ieft edge of dispiay unit) ciockwise for a visibie
raster. If none appears, adjust the RED color intensity control (A6) until a raster appears.
4. Depress the A6 test switch and adjust the focus control for the sharpest retrace lines.
5. Adjust the two A2 purity controls for an even red color throughout the raster.
6. Adjust the A44 height. width. vertical. and horizontal centering so all raster edges are at
least 1 cm inside the screen edges. Touch-up the A2 purity controls if necessary for
optimum red purity.
7. Perform a preliminary color intensity adjustment per the procedure on page 6-5.
High Voltage
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DO NOT ATTEMPT TO MEASURE THE CRT ANODE VOLTAGE.
This adjustment sets the high voltage level for the CRT anode.
Procedure
Note
If the A6 video drive assembly has been changed, perform a pre-
liminary color intensity adjustment before proceeding.
1. Set the switch on the A13 (A33, A53, or A54) assembly to its rear (white raster) position.
2. Set the brightness control to maximum.
3. Turn the High Voltage adjustment (A44) fully CCW for maximum high voltage.
4. Turn the High Voltage adjustment until the raster increases in width by approximately 0.5
cm on each side.