Specifications

Troubleshooting Adjusting the Display after Replacing the Main Deflection Board
Adjusting the Display after Replacing the
Main Deflection Board
After replacing the main deflection board, perform the following
adjustments for all three Macintosh modes (screen resolutions):
• 640x480 at 67 Hz
• 832x624 at 75 Hz
• 1152x870 at 75 Hz
1 Using the control strip (or the Monitors control panel),
select 1152x870, the highest of the three Macintosh screen
resolutions.
2 Open the Display Service Utility (DSU) and select Pattern
Selections: AppleVision 850/850AV.
3 Click the Adjust Geometry button.
Note: Clicking the Adjust Geometry button causes the DSU to
automatically check high voltage (EHT). If the high voltage is
out of range, the DSU will load a nominal value.
4 Refer to the procedure called “Checking High Voltage” in this
chapter to verify that the high voltage is 27 kV. If the high
voltage is not 27 kV, adjust the high voltage using the DSU,
the multimeter, and the high-voltage probe. Use the high
voltage slider control on the DSU to make final adjustments.
5 Using the DSU, select the focus pattern (percent signs).
Adjust horizontal and vertical focus controls (two top
controls on the flyback transformer) for best center-of-
screen performance. If necessary, readjust each focus
control to optimize overall focus.
Screen
Resolutions