Apple Macintosh Performa 577 - Manual (Page 133)

Adjustments Video - 12
3 Select the Screen Control
Panel in the Control
Panels folder. Drag the
brightness control to
midrange.
4 Using a hex-head plastic
adjustment tool, set the
red (RB), green (GB),
and blue (BB)
background controls to
the full
counterclockwise
positions.