Live Adjustment Rules
Some hardware failures obviously point to the need to replace the display or its components. In such cases, there's no need to supply power to the display. However, many times you can correct a display anomaly through adjustments to internal controls. In such cases, it's necessary to expose the internal controls while still leaving the display or Macintosh operational and turned on so that you can see the effects of the adjustments in real time. When making such live adjustments, be sure to use diagnostic tools such as the Display Service Utility to provide reliable test patterns.
Adjustments to CRTs vary depending on the display; however, the following basic adjustment rules apply to all models:
If the display isn't broken, ...
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